ALBERT

Notes: Using a representative sample of the 2001 National School-based Youth Risk Behavior Survey, this study investigated the contemporaneous and intertemporal relationship between the use of licit and illicit substances by American youth between the ages 12 and 18. The results indicated a strong contemporaneous relationship between smoking cigarettes, drinking alcohol, smoking marijuana, and using cocaine. The results supported the gateway hypothesis indicating that prior smoking of cigarettes is significantly associated with the probability of current marijuana and cocaine use, as prior drinking of alcohol is significantly associated with the probability of current marijuana and cocaine use. The results also showed that males had a higher probability of using cocaine than females, whereas black students had a higher probability of smoking marijuana and using cocaine than white students. Age and race were associated with marijuana and cocaine use, but cocaine use was further linked with the factors of gender, region, and metropolitan area. These findings could have implications for public policies regarding prevention.

Notes: Every pre-school child requires an adult to purchase and provide a variety of foods, to help ensure a balanced selection is included in the diet to avoid any nutritional deficiencies. Children under 5 years have a greater demand for nutrients and energy to support the body's requirements for growth and development than at any other time throughout their life cycle. The paper critically reviews the main factors that influence food choices made by parents on behalf of their pre-school child. Dietary deficiencies in inner city areas remain a challenge for the government, educators and health professionals. A particular concern is iron deficiency as the prevalence of anaemia is common especially in British pre-school children from various family backgrounds. Poor parenting skills often exacerbate the problem, especially the early introduction of pasteurized cow's milk, poor weaning practices and lack of dietary knowledge. Therefore, improving education and understanding about the importance of iron could potentially improve dietary iron intake. Phase 1 of the study was completed in West Bridgford area of Nottingham in the UK. This part of the study aimed to determine parental knowledge with regards to the feeding of their pre-school child. A questionnaire and a 3-day diet history method were employed. These methods enabled the diet adequacy of the pre-schoolers to be analysed by NetWISP software. This study highlighted that iron deficiency remains a cause for concern and should be further addressed. The Sure Start programme is a possible means of education as it has the potential to access parents from all socio-economic classes. The programme can support and empower parents to become healthier consumers. Good dietary habits, established early in life, contributes to a positive start, and can be advantageous to individuals throughout their lifetime. Such long-term changes will help contribute to a healthier nation that the government envisages for the future.

Notes: There is focus upon advertising and children for two broad reasons. First, it is because children are children, and are considered separately. Second, it is because children will become adults. Advertising therefore effects behaviour during childhood and continues to do so into adulthood. Advertising to children rarely receives a good press, and it remains a controversial topic in the wider domain. Is it responsible for poor diet? Does it make children pester their parents? Is there too much of it? And does Christmas have to start in September? Subsequently the issue has evolved to question whether there should be advertising to children, and if so whether it should be regulated. This discussion paper examines arguments for and against children's advertising, and concludes that whilst there are compelling arguments on both sides, advertising to children remains an economic necessity in need of adjustment and regulation.

Notes: The nutritional status of children can influence their health and the risk factors for developing chronic diseases later in life. Korea is unique in that it is relatively westernized and yet maintains much of the traditional foods and cooking methods. Effective nutrition education should help children to choose a healthy diet through the establishment of positive dietary practices and habits. The main purpose of this research is to compare awareness towards nutrition education between primary schools in the UK and Korea and nutritional knowledge that children and parents have in these countries. Dietary and healthy eating knowledge data were collected by a questionnaire as part of a case study comparison using one primary school in Manchester, UK, and one in Seoul, Korea. A total of 171 primary school children and 124 parents of the children were recruited. The results indicated that children and parents appeared to be aware of the importance of limiting fat, sodium and sugar intakes, and requiring non-starch polysaccharide (NSP). However, in the case of some foods they did not have satisfactory nutritional knowledge of which foods were high in fat, salt, sugar and NSP. British children had a better understanding of the health implication of fat than Korean children, whereas more Korean children considered excessive salt intake harmful than British children. There seemed to be differences in dietary pattern and familiarity with food between the two countries. Children identified parents as the main source of nutritional information. Therefore, parents as well as children need to learn about nutrition in order to give appropriate information or advice to improve the diets of their children. Children preferred exciting, fun, positive and a practical approach to learning about nutrition, such as computer packages and cookery classes. Parents wanted schools to give their children more information about nutrition. This research has shown that nutrition education in schools should be concerned not only to provide nutritional knowledge but also to encourage children to choose healthy food by redesigning nutrition education and school meals.

Notes: The nutritional habits of UK consumers have become a cause for concern with an increasing number of people suffering from diseases related to nutrition. The way in which food is prepared may contribute to the nutritional content of the diet. Traditional methods of cooking and eating are being influenced by increased ownership of domestic appliances. This study aimed to carry out a cross sectional study of people living on Merseyside to determine the ownership and use of small kitchen domestic appliances in relation to the possible consequences the appliances may have on the nutrient intake of the individual. An opportunistic sample of 276 female adults aged 25–70 years was recruited from amongst university staff and community groups within Merseyside. Data were collected using a self-completion questionnaire consisting of questions concerning personal details, the ownership and use of domestic appliances that may influence nutrient intake. The Liverpool John Moores University Ethics Committee granted ethical approval. Microwave ovens, electric toasters and grills were owned by 80% of the population. Coffee makers, handheld electric food mixers, sandwich makers, blenders and food processors although owned by over 45% were used by the majority only once a week or less. Newer items such as a bread maker were owned by 9% who were significantly more likely to have a professional occupation. Those with unskilled occupations were significantly more likely to own a deep fat fryer and least likely to own a food processor. Those aged 25–34 years were significantly least likely to own a handheld food mixer. Households comprised of couples with or without children were significantly more likely to own sandwich makers, bread makers, food processors and handheld food mixers. No difference in the use of the appliances was found with occupational group or age. A large percentage of people own a variety of domestic appliances, the use of which may have a beneficial effect on their nutrient intake, however, it is of concern that those in the lower socio-economic group were more likely to own appliances that will have a negative effect on their diet.

Notes: This qualitative study examined the consumption of Indian foods among groups of English and Indian people living in the UK. Both convenience and freshly made Indian foods were included in the research. The aim was to explore attitudes (based on ethnicity) towards, and the consumption of, Indian foods. The means–end model and laddering methodology were used in interviews with 24 respondents, 12 from each group (English and Indians). The personal values ‘social life’, ‘health’, ‘adventure’, ‘enjoyment’ and ‘savings’ were found to be the most important for English respondents whereas ‘enjoyment’, ‘good life’, ‘health’, ‘religion’ and ‘culture’ were the most desirable value ends for Indians. The results provide an insight into English and Indian peoples’ perceptions of Indian food that can be used in promotion and marketing positioning of branded Indian foods, sauces and accompaniments.

Notes: People are becoming more health conscious nowadays, but most of them are not able to adopt a lifestyle with adequate physical exercise and a healthier eating pattern. Many attempt to compensate by taking ‘health foods’. Despite the recent economic recession, the functional food market is expanding rapidly in Asian countries. Recent statistics indicate a huge increase in weight loss and functional food product advertising expenditure in Hong Kong and other Asian countries. In a large scale survey conducted by the Hong Kong Consumer Council on advertisements, it was found that 85% of the medicines, health food and therapies sampled contain questionable claims and misleading messages, which was the second most problematic category of the survey. In addition, young people do not understand much about modern food processing, in particular with regard to low energy and functional foods, and they know very little about modern food marketing strategies. The situation is potentially detrimental to consumer welfare, especially to the younger generation. This study was conducted to reflect critically on implications of the issue on the health and well-being of young people in Hong Kong. Attempts are made to explore directions for designing relevant and effective education programmes to empower young people's abilities in understanding food advertising strategies and making informed decisions on food choice. This paper begins with a critical review of the current situation with regard to Hong Kong. Then, the results of an interview survey and a questionnaire survey on pre-service and in-service teachers’ perception towards misleading food advertising and labelling are reported. The situations at schools are defined and problems faced by teachers in providing relevant consumer education programmes to students are identified. Finally, some prospective foci for further investigation of this important issue, with a view to developing students’ critical skills in evaluating claims offered in food advertisements, will be considered.

Notes: The aim of consumer education has been mainly to teach and educate students to act as informed, rational and prudent consumers. This perception of consumption as reasoned behaviour or action is inadequate in the late modern society, where consumerism is first and foremost characterized by globalization, cultural change and the liberation of the individual. The results of a research study involving Danish pupils aged 12–19 years present a picture of consumption connected both to material and non-material aspects of life. Consumption as such has a significant impact on and meaning for the individual: it becomes a means by which human beings communicate and interact. Consumption is part of children's and young people's education and socialization, and plays a role in the development of identity and self-image. Institutional consumer enlightenment and the education of students in school stand in contrast to informal consumer  socialization  and  the  education  of  individuals. The aim of formal consumer education may be described as ‘educating for critical consumer awareness and action competence’. However consumer education finds itself in the dilemma between ‘consumership’ and ‘citizenship’. This pilot study is aimed at understanding consumer socialization in order to improve formal consumer education and to reflect on how empowerment becomes part of consumer education.

Notes: Ethical attitudes in relation to meat purchases were studied among urban and rural consumers in Scotland. All subjects perceived at least some ethical issues in relation to animal production systems, in particular, systems keeping animals in close confinement. Welfare-friendly production systems were viewed as adding value to a food, but this value was not necessarily realizable to producers if purchases occurred only when foods were on special offer. Statements made by individuals were often contradictory, revealing ambivalence, unresolved value conflicts and a general lack of involvement in the nature of meat production. A number of barriers to the establishment of stable attitudes and behaviours in relation to the ethical treatment of food animals were also identified. A key finding of the study is that individuals can hold two views on animal welfare. On the one hand, they may think as citizens influencing societal standards, and on the other, as consumers at the point of purchase. As citizens, they support the notion of animals being entitled to a good life; as meat consumers, they avoid the cognitive connection with the live animal. This paper explores both the citizen–consumer relationship and purchase strategies used by consumers to resolve value conflicts. Lessons for public and commercial policy are highlighted in the context of the Curry Report (2002) which advocates more effective market segmentation where markets are finely attuned to their customers, with the development of a number of assurance schemes discussed in the article.

Notes: 1 The effects of the immunosuppressants, tacrolimus (FK506) and cyclosporin A (CsA), on catecholamine (CA) release were examined in cultured bovine adrenal chromaffin cells. 2 In intact cells, FK506 (1–30 μm) inhibited CA release stimulated by acetylcholine (ACh; 100 μm), 1,1-dimethyl-4-phenyl-piperazinium (DMPP, 10 μm) or high K+ (40 mm). CsA (1–30 μm) had a little inhibitory effect on the ACh- or DMPP-stimulated CA release, whereas it enhanced the high K+-stimulated CA release. 3 In β-escin-permeabilized cells, FK506 inhibited CA release stimulated by Ca2+ (1 and 10 μm) in the presence and absence of MgATP (2 mm). CsA induced CA release under Ca2+-free condition and enhanced the Ca2+-stimulated CA release in the presence and absence of MgATP. 4 It is known that the Ca2+-dependent exocytosis involves at least two distinct steps, ATP-requiring priming stage and ATP-independent fusion step in adrenal chromaffin cells. Therefore, it is suggested that FK506 inhibits the Ca2+-dependent exocytosis probably at the fusion step whereas CsA induces CA release from bovine adrenal chromaffin cells.

Notes: 1 Prolonged bed rest or exposure to microgravity may cause several alterations in autonomic nervous system response (ANSR). 2 Hindlimb unloading (HU) rats were used as an animal model of simulated microgravity to investigate ANSR changes. The experiments were carried out to investigate the effects of simulated microgravity on the autonomic nervous response of the perfused mesenteric vascular bed (MVB), vas deferens and the colon and duodenum from 2-week HU rats. 3 In MVB preparations of HU rats, the frequency-dependent increases in perfusion pressure with perivascular nerve stimulation (PNS; 8–40 Hz) were inhibited, whereas the noradrenaline (NA) concentration-dependent (1–100 μm) perfusion pressure increases were potentiated. The latter most probably reflected up-regulation of α-adrenergic receptor function. Relaxant responses of NA-precontracted MVB to PNS (4–30 Hz) or isoprenaline were not different between control and HU preparations, while vasodilation induced by the endothelial agonist ACh was reduced. 4 Transmural stimulation (2–40 Hz) induced frequency-dependent twitches of the vas deferens which were reduced in vas deferens of HU rats, while the sensitivity to NA-induced contraction was significantly increased. 5 In the gastroenteric system of HU rat, direct contractile responses to carbachol or tachykinin as well as relaxant or contractile responses to nervous stimulation appeared unchanged both in the proximal colon rings and in duodenal longitudinal strips. 6 In conclusion, HU treatment affects peripheral tissues in which the main contractile mediators are the adrenergic ones such as resistance vessels and vas deferens, probably by reducing the release of neuromediator. This study validates NA signalling impairment as a widespread process in microgravity, which may most dramatically result in the clinical phenotype of orthostatic intolerance.

Notes: 1 This double-blind, cross-over, placebo-controlled study on six healthy male volunteers was designed to evaluate the effects of α2-adrenoceptor antagonism on cardiac parasympathetic regulation. 2 The subjects received atipamezole intravenously as a three-step infusion, which aimed at steady-state serum concentrations of 10, 30 and 90 ng ml−1 at 50-min intervals. 3 Drug effects were assessed with repeated recordings of blood pressure and electrocardiogram, in which the high-frequency (0.15–0.40 Hz) R-R interval variation is supposed to reflect cardiac parasympathetic efferent neuronal activity. 4 At the end of the three steps of the infusion, the mean (±SD) concentrations of atipamezole were 10.5 (3.9), 26.8 (5.6) and 81.3 (21.1) ng ml−1. 5 Within this concentration range, atipamezole appeared to reduce slightly the high-frequency R-R interval fluctuations, indicating a minor vagolytic effect in the heart. 6 Atipamezole increased systolic and diastolic arterial pressure, on average by 20 and 14 mmHg (maxima at the second step of the infusion), which evidently reflects an overall sympathetic augmentation.

Notes: 1 We have compared vasoconstriction responses in isolated mesenteric small arteries from mice and rats as elicited by KCl, noradrenaline and the lysosphingolipids sphingosine-1-phosphate (S1P) and sphingosylphosphorylcholine (SPC). 2 Contractile responses to KCl and noradrenaline, but not those of S1P or SPC, were significantly related to vessel diameter in both species. 3 When comparing vessels of similar diameter, contractile responses for KCl and the three agonists were much smaller in mice than in rats, e.g. 8.3 ± 0.4 vs. 14.7 ± 0.7 mn for noradrenaline. 4 Based upon the antagonist rank order of potency of prazosin (pKB 8.80) 〉 B8805-033 (pKB 7.89) 〉 yohimbine (pKB 6.18) ≈ BMY 7378 (pA2 6.03), noradrenaline responses in mice were mediated solely via α1A-adrenoceptors, similar to what repeatedly has been shown in rats. 5 The S1P3 receptor antagonist suramin (100 μm) significantly inhibited responses to S1P and SPC in rats but not in mice, and did not affect noradrenaline responses in either species. 6 We conclude that for any given diameter, mouse mesenteric arteries develop less contraction in response to various stimuli. Noradrenaline acts via α1A-adrenoceptors in both species. Responses to S1P and SPC differ between both species with regard to suramin-sensitivity indicating involvement of different receptor subtypes for lysosphingolipids in both species.

Notes: 1 A fructose (Fru)-enriched diet induces a mild increase in blood pressure associated with hyperglycaemia, hypertriglyceridaemia, and insulin resistance, resembling the human ‘syndrome X’, being an useful model to study hypertension and type 2 diabetes. 2 A sustained elevation of blood pressure is associated with cardiovascular structural modifications such as left ventricular hypertrophy and increased wall thickness:lumen diameter ratio in blood vessels. 3 Prostanoids (PR), metabolites of arachidonic acid through the cyclooxygenase pathway, include vasoactive substances synthesized and released by the vessel walls. 4 The aim of the present study was to analyse, in Fru-treated rats: (i) the morphology of mesenteric vessels and; (ii) the PR production in aorta and mesenteric vessels, in order to assess whether these parameters are related with the haemodynamic alterations observed in this experimental model. 5 Blood pressure, glycaemia and triglyceridaemia, were significantly elevated in both (4 and 22 weeks) Fru-treated groups. Meanwhile body and heart weight as well as insulinaemia were similar between experimental animals and controls. 6 The mesenteric vessels of Fru-treated rats (22 weeks) showed an increased thickness and area of the media when compared with the controls; meanwhile, the lumen diameter was similar in both groups. 7 The Fru treatment for 4 weeks did not modify PR production in aorta, whereas in the mesenteric bed it diminished prostaglandin (PG) E2 release significantly compared with the controls. However, in the group treated for 22 weeks, Fru reduced PGI2 production in the aorta, as assessed by 6-keto-PGF1α measurements. Meanwhile, in the mesenteric bed, the chronic Fru treatment decreased PGE2 release but, rather surprisingly, increased the output of PGI2 when compared with its corresponding controls. 8 In conclusion, the present study shows the existence of an alteration in the morphology of mesenteric vessels in Fru-treated rats, which could be related to an increase in peripheral resistance and the consequent mild hypertension observed in this model. However, a diminished release of vasodilator PRs, such as PGE2 in mesenteric vessels at 4 and 22 weeks and PGI2 in aorta at 22 weeks could further impair the vessel response. The increase in PGI2 observed in the chronic group in mesenteric vessels could be attributed to a compensatory mechanism.

Notes: 1 Electrical field stimulation (EFS) (0.5 ms in train of 2–32 Hz for 300 ms) in smooth muscle of pigeon oesophagus, in the presence of atropine (1 μm) and guanethidine (1 μm), elicited an inhibitory response consisting of a transient hyperpolarization (inhibitory junction potential, IJP) associated with muscle relaxation. 2 Sodium nitroprusside (SNP, 100 μm) induced hyperpolarization correlated to mechanical relaxation. 3 The nitric oxide (NO) synthase inhibitor Nω-nitro-l-arginine (from 0.1 to 100 μm) caused a concentration-dependent reduction of electromechanical response to EFS indicating a role for NO in this response. 4 Apamin (1 μm) reduced both IJP and relaxation to EFS but was without effect on the response to SNP indicating a role for purines, which are also blocked by apamin. 5 Adenosine, AMP, ADP and ATP (all from 1 μm to 1 mm) application caused transient hyperpolarization and muscular relaxation with the following order of potency: adenosine 〉 AMP 〉 ADP 〉 ATP. 6 Inhibitory responses evoked by purines are TTX (1 μm) insensitive but they were inhibited by apamin. This indicates that a purine component for the non-adrenergic non-cholinergic (NANC) response exists but the purine receptor site is not located on the neurone. 7 Overall these results suggest that NANC inhibitory response elicited by EFS presents two different components apamin-sensitive, probably purines-mediated and apamin-insensitive probably NO-mediated as apamin only partially block the response to EFS.

Notes: 1 Sibenadet (Viozan®), a dual dopamine D2/β2-adrenoceptor agonist, suppresses histamine-induced tachypnoea in the dog by activating dopamine D2 receptors. We here compare the effects of sibenadet and formoterol, a selective β2-adrenoceptor agonist, on histamine-induced tachypnoea in the rhesus monkey. 2 Anaesthetized, spontaneously breathing, rhesus monkeys were set up for measuring airways resistance, respiratory rate, blood pressure and heart rate. 3 Both sibenadet and formoterol administered by aerosol, induced inhibition of the bronchoconstrictor response to aerosolized methacholine accompanied by tachycardia. Sibenadet, but not formoterol, also reduced blood pressure. 4 Administration of histamine by inhalation induced tachypnoea which was accompanied by bronchoconstriction. Tachypnoea to histamine was suppressed by both sibenadet and formoterol at doses which manifest anti-bronchoconstrictor activity. These effects and the accompanying tachycardia but not the hypotension induced by sibenadet were abolished by pretreatment with propranolol. 5 The dopamine D2 receptor agonist, quinagolide, did not suppress tachypnoea to histamine despite inducing a fall in blood pressure indicating activation of dopamine D2 receptors. 6 Thus, both sibenadet and formoterol suppress histamine-evoked tachypnoea in the rhesus monkey. The effect arises exclusively through activation of β2-adrenoceptors and probably reflects the anti-bronchoconstrictor effects of these agents. The results reveal a fundamental difference in the role of dopamine receptors in the airways of dog and rhesus monkey.

Notes: 1 We have investigated the actions of the calcium entry blockers nifedipine, R-verapamil and S-verapamil in rat aorta, colon and vas deferens. 2 In aorta and colon, these agents produced concentration-dependent relaxations of KCl (80 mm)-induced contractions. In both tissues, the order of potency was nifedipine 〉 S-verapamil 〉 R-verapamil. However, nifedipine showed selectivity for aorta (potency ratio, colon/aorta: 4.36), S-verapamil showed no selectivity (0.62), but R-verapamil showed selectivity for colon (0.19). 3 In prostatic portions of rat vas deferens, nifedipine (10 μm) abolished the contraction to a single electrical stimulus, but R- and S-verapamil were without effect. In epididymal portions of rat vas deferens, R- and S-verapamil inhibited α1-adrenoceptor-mediated contractions to a single electrical stimulus at concentrations of 10 μm and above. 4 In conclusion, R-verapamil may prove useful as an intestinal selective calcium entry blocker in the treatment of intestinal disease with a hypermotility component, e.g. irritable bowel syndrome.

Notes: 1 The present study was carried out to pharmacologically identify the β-adrenoceptor subtype that mediates isoprenaline-elicited relaxation in the isolated guinea-pig tracheal smooth muscle, to answer the question whether it is β1- or β2-subtype? 2 Isoprenaline as well as salbutamol, a well-known β2-selective adrenoceptor agonist, produced a concentration-dependent relaxation with a pD2 value of 8.12 vs. 7.54 for salbutamol. 3 Isoprenaline-elicited relaxation was not affected by β1-selective antagonists, atenolol and CGP-20,712A, within the concentration ranges supposed to antagonize β1-subtype: atenolol, ≤10−6 m; CGP-20,712A, ≤10−8 m. 4 By contrast, the concentration–response curves for isoprenaline as well as salbutamol were shifted rightwards in a competitive fashion by atenolol at the concentrations ≥3 × 10−6 m. However, pA2 values of atenolol against isoprenaline (5.86) and salbutamol (5.71) were consistent with the value corresponding to β2- but not to β1-subtype (around 7.00), and these values were not significantly different from each other. 5 Competitive antagonism of the relaxations to isoprenaline and salbutamol were also obtained with β2-selective antagonists, butoxamine and ICI-118,551. Against isoprenaline and salbutamol, the pA2 values of butoxamine (6.51 vs. 6.81) and ICI-118,551 (8.83 vs. 8.90) were substantially identical. Thus the primary mediation of β2-receptor in the relaxations was strongly supported. 6 The present findings provide evidence that the β-adrenoceptor which mediates isoprenaline-elicited relaxation of guinea-pig tracheal smooth muscle is essentially β2- but not β1-subtype. The present study also indicates the importance of using multiple receptor antagonists with different pA2 values to pharmacologically identify the responsible receptor subtype in smooth muscle mechanical responses.

Notes: 1 The role of histamine in heat-induced cardiovascular changes is uncertain. The purpose of this study was to examine effects of histamine H-1- and H-2-antagonism on heart rate, mean arterial blood pressure (MAP), localized body temperature changes, survival times, and lethal body temperatures that occur during the exposure of anaesthetized rats to 35 GHz radio frequency radiation (RFR). 2 Forty-eight ketamine-anaesthetized Sprague–Dawley rats were exposed, in several different treatment groups (n = 8 in each), to 35 GHz RFR at a level that resulted in significant body heating and subsequent death. During irradiation, a continuous increase in heart rate and a biphasic response in blood pressure (initial increase followed by a decrease) were observed in all groups of animals. 3 An H-1-antagonist, diphenhydramine (1 mg kg−1 body wt) and an H-2-antagonist, cimetidine (5 mg kg−1), administered after sustained RFR exposure, failed to reverse the RFR-induced hypotension. High doses of the drugs (5 and 10 mg kg−1, respectively) also did not alter the response. Post-RFR survival time was significantly decreased in the high-dose drug-treated group, compared with vehicle-treated (0.9% NaCl, 50% ethanol and 50% D5W) controls. 4 In experiments in which the two drugs were administered prior to RFR exposure, MAP in animals receiving high-dose antihistamines was significantly depressed compared with that of vehicle-treated animals during the first 35 min of RFR exposure. Antihistamine pretreatment, however, did not alter the total RFR exposure time required for death to occur. 5 In summary, pharmacological blockade of H-1 and H-2 receptors is not beneficial in anaesthetized rats made hypotensive by RFR exposure. This indicates that activation of H-1 and H-2 receptors by histamine does not occur to any significant extent and does not mediate the hypotensive response developed in this model of hyperthermia.

Notes: 1 The great taxonomic and prey base diversity of colubrids (non-front-fanged snakes) suggests that their venoms may represent a ‘literal gold mine’ for scientists eager to find novel pharmacological probes (Mackessy, 2002). 2 While pharmacological characterization is lacking for most of these venoms, this is even more so with regard to activity of colubrid venoms on the mammalian autonomic nervous system. This study characterizes the activity of venom from the colubrid, Boiga dendrophila using in vitro smooth muscle preparations and the anaesthetized rat. 3 In the prostatic segment of the rat vas deferens, cumulative additions of venom (1–150 μg ml−1) induced concentration-dependent inhibition of electrically evoked (0.2 Hz, 0.3 ms, 70–100 V) twitches. The inhibitory effect of venom (100 μg ml−1) was attenuated by 8-phenyltheophylline (8-PT) (20 μm) and 8-cyclopentyl-1, 3-dipropylxanthine (20 μm) but not idazoxan (1 μm), or a combination of ranitidine (0.2 μm) and thioperamide (10 μm). The inhibitory effect of venom (100 μg ml−1) was augmented by dipyridamole (10 μm) but abolished by pretreatment with adenosine deaminase (7.5 units/100 μl) suggesting that it contains components with adenosine A1 receptor activity, most likely adenosine. 4 In isolated segments of guinea-pig ileum, venom (10–100 μg ml−1) caused concentration-dependent contractions which were inhibited by the muscarinic receptor antagonist atropine (0.1 μm) but not by the histamine receptor antagonist mepyramine (0.5 μm). 5 In the anaesthetized rat, venom (5–7.5 mg kg−1, i.v.) caused a hypotensive effect. 6 Our data suggest that the venom contains components with purinergic and muscarinic receptor activity.

Notes: 1 β-Adrenoceptor (AR) ligands have been the mainstay of cardiovascular therapy for decades, with β-AR antagonist being used for hypertension, angina and myocardial infarction and adrenaline in use for cardiopulmonary resuscitation for nearly 100 years. 2 Ischaemia of the heart through coronary artery occlusion causes cell injury and death through necrosis and apoptosis. Reperfusion of the ischaemic myocardium results in cardiac dysfunction and infarction. 3 Stimulation of α- and β-ARs in the ischaemic heart have variable and inconsistent effects depending on when the agonist is applied. This review describes the different effects of stimulation of the three established β-AR subtypes (β1-, β2- and β3-ARs) either before ischaemia (preconditioning) or during ischaemia and reperfusion of the heart (postconditioning). 4 Brief periods of ischaemia preceding a major ischaemic episode can have a protective effect against post-ischaemia–reperfusion damage, known as ischaemic preconditioning. This review considers the role of endogenous catecholamines released during preconditioning and the nature of the adrenoceptor subtypes that mediate these effects. The clinical significance of this to the use of β-AR antagonists is considered. 5 The transduction pathways and effects on apoptosis of the cardioprotective and deleterious effects of AR activation are considered. 6 This commentary reviews the literature and attempts to bring together a unified synopsis of the effects of adrenoceptor stimulation in myocardial ischaemia and the potential clinical relevance.

Notes: 1 Cupric ions (Cu2+), at concentrations above 0.03 mm, induced a progressive increase in the tonic contraction of guinea-pig ileal longitudinal muscle. Maximal contraction of 0.1 mm Cu2+ attained a level above that of the 60-mm K+-induced tonic response, within 20 min of application. The tension induced by Cu2+ persisted for more than several hours. Tetrodotoxin (3 × 10−6 m) had no effect on the contraction induced by 0.1 mm Cu2+. 2 After incubation in a Ca2+-free medium, the ileal response to 0.1 mm Cu2+ was lost. Nifedipine, a L-type Ca2+ channel blocker, dose-dependently inhibited contractions induced by Cu2+. 3 As the duration of the first application of 0.1 mm Cu2+ increased above 30 min, after washing with normal medium, the contractile response to a second application of 0.1 mm Cu2+ decreased gradually. After 150 min of the first application of 0.1 mm Cu2+, a second application of Cu2+ could not evoke any contraction. 4 After the application of 0.1 mm Cu2+ for 150 min, when muscles were washed with a medium containing 1 mm EDTA, the response to 0.1 mm Cu2+ returned to a greater extent in the normal Ca2+ medium. 5 In conclusion, Cu2+ (0.1 mm) induced a maximal ileal tension above that of the K-induced tonic response within 20 min. The ileal contraction to Cu2+ persisted for more than several hours and depended on extracellular Ca2+ concentrations. It is possible that a part of Cu2+, bound to a EDTA-inaccessible site, also has a tension inhibitory effect.

Notes: 1 Anthraquinone stimulant cathartics, such as emodin, are believed to increase the rate of contraction of ileum tissue in vitro via multiple mechanisms. The aim of this study was to probe the effects of emodin on acetylcholine (ACh)-induced contraction of the rat isolated ileum preparation. 2 Ileal sections were incubated in Tyrode's solution and responses to methacholine, ACh and emodin obtained in the absence and presence of the muscarinic antagonist atropine and the choline uptake inhibitor hemicholinium (HC-3). Depletion of endogenous ACh in the presence of HC-3 was achieved by construction of an ACh dose–response curve, using exogenous ACh, prior to re-testing the effects of emodin in the presence of HC-3. 3 Emodin caused dose-dependent tissue contraction that was abolished by inclusion of atropine (1 μm) in the buffer. Atropine (1 μm) antagonized the response caused by methacholine. 4 Incubation of tissues with HC-3 (1 and 10 μm) reduced the maximum response caused by emodin by 45% and 71% respectively, but had no effect on ACh-induced tissue contraction. 5 These data suggest that, emodin causes contraction of the ileum by triggering the release of endogenous ACh which acts on muscarinic receptors to cause contraction of the rat isolated ileum preparation.

Notes: Soil cracks formed by natural processes play a key role in water and gas transfer. Patterns of soil cracks are, however, difficult to characterize. Our aim here is to assess the effectiveness of three-dimensional electrical resistivity surveys in detecting soil crack networks. A three-dimensional electrical survey was carried out by a square array quadripole with Cu–CuSO4 electrodes (electrode spacing of 3 cm). The measurements were made with two orientations (0° and 90°) on a block (26 cm × 30 cm × 40 cm) of soil while it dried for 18 days under controlled conditions. Two indexes, calculated from the apparent resistivity values, were evaluated to detect the degree of soil heterogeneity: (i) an anisotropy index based on the ratio between the apparent resistivity at 0° and that at 90°; and (ii) the angle-array orientation corresponding to the preferential anisotropic orientation (maximum resistivity). The anisotropy index provided information on the presence of cracks and the orientation for crack width 〉 1 mm in the first pseudo-depth (i.e. depth of investigation), while the angle-array orientation provided information on crack extension for the whole pseudo-depth. Information about the presence, position, orientation and extension of cracks can be obtained from an analysis of apparent resistivity obtained by a three-dimensional electrical survey. Such direct analysis will help the resistivity inversion to detect the crack network.

Notes: The podzolization process is studied through lipids in nine characteristic podzol horizons. Organic matter accumulates particularly with aluminium in the Bh horizon, while the hard, cemented Bs horizon below this is formed mainly by iron oxides. The low soil pH seems to have no great influence on the preservation of lipids as reflected by the absolute amounts present and the presence of bacterial lipid markers throughout the profile. Independent of soil pH, lipids accumulate in organically enriched horizons. Albeit, high molecular weight organic compounds accumulate to a relatively greater extent than lipids in these horizons. A lipid signal related to the aerial parts, i.e. leaves and flowers, of Calluna is observed only in the O horizon. This ‘n-alkane, steroid and triterpenoids’ signal is quickly lost in the underlying Ah horizon due to (bacterial) oxidation. The other total lipid extracts obtained are dominated by root-derived compounds. In subsoil horizons rich in organic matter, i.e. the Ahb and Bh horizons, root-derived friedooleanan and steroid compounds dominate the total lipid signal. Degraded horizons, poor in organic matter, i.e. the E2, Bhs, Bs and B/C horizons, are dominated by C22 and C24ω-hydroxy acids, long-chain (〉 C20) n-alkanoic acids with a strong even-over-odd predominance and C22 and C24n-alkanols. Steroid and root-derived triterpenoids with a friedooleanan structure have been removed from these horizons through degradation. Based on total organic carbon content and lipid composition, the formation of an E1 horizon has started, but is not yet complete. In the Ahb horizon, a contribution from buried vegetation to the total lipid signal is still present, although degradation and an input from roots have significantly altered the original signal. Overall, lipid data indicate that degradation (microbial oxidation) is an important process that should be taken into account, in addition to leaching, when describing podzolization processes in soils.

Notes: Measurement of soil respiration to quantify ecosystem carbon cycling requires absolute, not relative, estimates of soil CO2 efflux. We describe a novel, automated efflux apparatus that can be used to test the accuracy of chamber-based soil respiration measurements by generating known CO2 fluxes. Artificial soil is supported above an air-filled footspace wherein the CO2 concentration is manipulated by mass flow controllers. The footspace is not pressurized so that the diffusion gradient between it and the air at the soil surface drives CO2 efflux. Chamber designs or measurement techniques can be affected by soil air volume, hence properties of the soil medium are critical. We characterized and utilized three artificial soils with diffusion coefficients ranging from 2.7 × 10−7 to 11.9 × 10−7 m2 s−1 and porosities of 0.26 to 0.46. Soil CO2 efflux rates were measured using a commercial dynamic closed-chamber system (Li-Cor 6400 photosynthesis system equipped with a 6400-09 soil CO2 flux chamber). On the least porous soil, small underestimates (〈 5%) of CO2 effluxes were observed, which increased as soil diffusivity and soil porosity increased, leading to underestimates as high as 25%. Differential measurement bias across media types illustrates the need for testing systems on several types of soil media.

Notes: Soil texture and degree of aggregation affect the stabilization of organic matter. We studied their influences in silty soils using samples from two field experiments with contrasting long-term use (cropped versus bare fallow). The cropped soil had a larger organic C content than the bare fallow, and allowed us to compare a soil with pools of organic C differing in turnover time with a soil dominated by the passive organic C pool. Increasingly dispersive treatments applied to the soils yielded aggregates of various sizes, stabilities, and organic matter contents. We found an intimate interaction between soil structure and organic matter by demonstrating that aggregation is hierarchical and that active pools of organic matter are responsible for this hierarchy. Microaggregates were found to consist of a constant ratio of clay to silt particle-size fractions. We propose that such a property be used to estimate true microaggregation and aggregate stability by estimating the amount of soil material dispersed by a given treatment. Organic matter associated with clay is confirmed as an important sink of long-term stabilized C, and it appears to have been increasingly preserved when in increasingly larger aggregates. However, most of the soil mass and associated organic C is in smaller aggregates. We hypothesize that the physical protection within macroaggregates does not directly control long-term stabilization of organic C in the soil, but rather contributes indirectly through the time and local conditions it offers for organic matter to gain chemical or physico-chemical protection by interacting with the soil environment.

Notes: Analysis of soil lipids may contribute to an improved understanding of atmosphere to soil carbon fluxes, soil organic matter source differentiation and pollutant accumulation. Soil lipids, mostly originating from plants and microorganisms, have traditionally been analysed by non-automated extraction and separation methods, which produce several lipid fractions, operationally defined by polarity. Here we present a combination of fast, automated and reproducible techniques, adopted from organic geochemical studies, for preparative separation of individual soil lipid fractions with increasing polarity. These techniques involve commercially available instruments, including accelerated solvent extraction and a two-step automated medium-pressure liquid chromatography procedure. The method yields eight lipid fractions consisting of five fractions fully amenable to gas chromatography/mass spectrometry (GC/MS) (aliphatic hydrocarbons, aromatic hydrocarbons, ketones, alcohols, carboxylic acids), and three fractions of highly polar or high molecular weight compounds (bases, very long-chain wax esters (C40+), high polarity compounds) that were not measurable with GC/MS under standard conditions. We tested the method on five agricultural soils. Results show that (i) mass recoveries for the individual fractions are reproducible, (ii) within individual fractions compound distribution patterns are reproducible, as demonstrated for alkanes and carboxylic acids, and (iii) individual fractions represent distinct and clean compound classes, free of interfering substances detectable by GC/MS. Thus, automated separation can be a fast, effective and reproducible procedure for fractionation of complex mixtures of soil lipids into clean compound classes, directly suitable for a variety of molecular (e.g. GC/MS) and isotopic characterizations (e.g. gas chromatography coupled with isotope ratio monitoring mass spectrometry or accelerator mass spectrometry).

Notes: Clear-cutting of forest provides a unique opportunity to study the response of dynamic controls on dissolved organic matter. We examined differences in concentrations, fluxes and properties of dissolved organic matter from a control and a clear-cut stand to reveal controlling factors on its dynamics. We measured dissolved organic C and N concentrations and fluxes in the Oi, Oe and Oa horizons of a Norway spruce stand and an adjacent clear-cutting over 3 years. Aromaticity and complexity of organic molecules were determined by UV and fluorescence spectroscopy, and we measured δ13C ratios over 1 year.Annual fluxes of dissolved organic C and N remained unchanged in the thin Oi horizon (∼ 260 kg C ha−1, ∼ 8.5 kg N ha−1), despite the large reduction in fresh organic matter inputs after clear-cutting. We conclude that production of dissolved organic matter is not limited by lack of resource. Gross fluxes of dissolved organic C and N increased by about 60% in the Oe and 40% in the Oa horizon upon clear-cutting. Increasing organic C and N concentrations and increasing water fluxes resulted in 380 kg C ha−1 year−1 and 10.5 kg N ha−1 year−1 entering the mineral soil of the clear-cut plots. We found numerous indications that the greater microbial activity induced by an increased temperature of 1.5°C in the forest floor is the major factor controlling the enhanced production of dissolved organic matter. Increasing aromaticity and complexity of organic molecules and depletion of 13C pointed to an accelerated processing of more strongly decomposed parts of the forest floor resulting in increased release of lignin-derived molecules after clear-cutting. The largest net fluxes of dissolved organic C and N were in the Oi horizon, yet dissolved organic matter sampled in the Oa horizon did not originate mainly from the Oi horizon. Largest gross fluxes in the Oa horizon (control 282 kg C ha−1) and increased aromaticity and complexity of the molecules with increasing depth suggested that dissolved organic matter was derived mainly from decomposition, transformation and leaching of more decomposed material of the forest floor. Our results imply that clear-cutting releases additional dissolved organic matter which is sequestered in the mineral soil where it has greater resistance to microbial decay.

Notes: Lysimeters are valuable for studying the fate and transport of chemicals in soil. Large-scale field lysimeters are used to assess pesticide behaviour and radionuclide transport, and are assumed to represent natural field conditions better than laboratory columns. Field lysimeters are usually characterized by a free-draining lower boundary. As a result, the hydraulic gradient is disrupted, and leachate cannot be collected until the bottom of the lysimeter becomes saturated. We compared heterogeneously structured, free-drainage lysimeters and field soils with respect to water flow and solute transport. Numerical simulations were carried out in a two-dimensional heterogeneous sandy soil under unsaturated water flow conditions with the CHAIN_2D code. Three different soil structures (isotropic, horizontal, and vertical) were generated, and Miller–Miller similitude was used to scale the hydraulic properties of the soil. The results showed that ponding occurs at the bottom of the lysimeter for the three soil structures and that it occurred faster and was more pronounced with the vertical structure (preferential flow effect). Breakthrough curves of a conservative solute (bromide) showed that solutes are moving faster in the field than in the lysimeters. Fewer differences between lysimeters and field soils were found with the horizontal soil structure than with the isotropic and vertical structures.

Notes: To improve the predictive capability of transport models in soils we need experimental data that improve their understanding of properties at the scale of pores, including the effect of degree of fluid saturation. All transport occurs in the same soil pore space, so that one may intuitively expect a link between the different transport coefficients and key geometrical characteristics of the pores such as tortuosity and connectivity, and pore-size distribution. To understand the combined effects of pore geometry and pore-size distribution better, we measured the effect of degree of water saturation on hydraulic conductivity and bulk soil electrical conductivity, and of degree of air saturation on air conductivity and gaseous diffusion for a fine sand and a sandy loam soil. To all measured data were fitted a general transport model that includes both pore geometry and pore-size distribution parameters. The results show that both pore geometry and pore-size distribution determine the functional relations between degree of saturation, hydraulic conductivity and air conductivity. The control of pore size on convective transport is more for soils with a wider pore-size distribution. However, the relative contribution of pore-size distribution is much larger for the unsaturated hydraulic conductivity than for gaseous phase transport. For the other transport coefficients, their saturation dependency could be described solely by the pore-geometry term. The contribution of the latter to transport was much larger for transport in the air phase than in the water phase, supporting the view that connectivity dominates gaseous transport. Although the relation between effective fluid saturation and all four relative transport coefficients for the sand could be described by a single functional relation, the presence of a universal relationship between fluid saturation and transport for all soils is doubtful.

Notes: The aim of this study was to validate the use of laser granulometry in studies concerning fractions 〈 2 µm in soils. The study was carried out on the clay fraction of a loamy soil from northeast Thailand. Granulometry by light scattering requires the determination of the refractive indexes of the solid phases. Once these values have been established, laser granulometry can provide a detailed description of the particle-size distribution within the clay fractions. Laser granulometry showed a multimodal distribution in the clay fraction of this soil.The analysis of images obtained by transmission electron microscopy provided numerical distributions of soil particles, from which representations by surface area and by volume obtained by laser granulometry and by transmission electron microscopy could be compared. The representation of particle-size distribution by surface area, assuming that particles are similar to circles, is adequate and, in this range of particle size, minimizes the effect of larger diameters. The representation of the particle-size distribution assuming that particles are similar to platy discs is better than the current representation that assumes particles are similar to spheres. We used transmission electron microscopy to validate laser granulometry in the fractions 〈 2 µm.Elemental microanalysis was used to identify the mineralogy of the clay particles: illite, illite-smectite and kaolinite at a magnification of 31 000, corresponding to the clay fraction 〈 0.8 µm of the particle-size distribution. Quartz and illite were identified at a magnification of 3300, corresponding to the fraction between 0.8 and 2 µm. The mineral constituents of the soil are correlated with the modes of the particle-size distribution.

Notes: Preservation of organic matter in soils depends on the chemical structure of organic compounds and on the surface properties of the mineral matrix. We tested the effect of mineral surface reactivity on organic matter decomposition by (i) investigating changes of organic matter composition in clay subfractions of an illitic Haplic Chernozem along a time series of fertilizer deprivation and (ii) simultaneously characterizing the reactivity of mineral surfaces. The soil was subjected to fertilizer deprivation for 18, 44 and 98 years, respectively. Mineral surface properties were characterized by selective dissolution of pedogenic oxides. The number of hydroxyls released after exposure to sodium fluoride was taken as an index for mineral surface reactivity. Organic soil constituents were determined by 13C cross-polarization magic-angle spinning nuclear magnetic resonance (13C CPMAS NMR).Clay subfractions had different mineral surface properties. The coarse fractions have more reactive surfaces and contain more organic carbon than the fine clay fractions. Mineral surface properties are constant over time and are not affected by fertilizer deprivation. Surface reactivity is a function of iron oxide density and controls carbon concentrations in the clay subfractions. Within the time frame of our investigation, alkyl C and aromatic C responded to the duration of fertilizer deprivation, but were indifferent to mineral surface reactivity. O–alkyl C seems to be protected by interactions with pedogenic oxides.

Notes: The determination of radio-labile metals in soil has gained renewed interest for predicting metal availability. There is little information on to what extent the fraction of labile metal is affected by the soil properties and the source of metal contamination. The radio-labile content (E value) of Cd and Zn was measured in field-collected soils with Cd and Zn originating from different sources. The E values were erratic and sometimes even exceeded total metal content when the concentration in the soil extract was less than 8 μg Zn l−1 or less than 3 μg Cd l−1. Addition of EDTA (0.1 mm) to the radio-labelled soil suspension resulted in larger concentrations of Cd and Zn in solution and smaller E values for these soils. The E values were, however, unaffected by the presence of EDTA (0.1 mm) in soils with larger concentrations of Cd and Zn in solution.The %E values (E value relative to metal soluble in aqua regia) ranged from 9% to 92% (mean 61%) for Cd and from 3% to 72% (mean 33%) for Zn. No correlation between soil properties and %E was observed for Cd, and the %E of Zn was negatively correlated with soil pH (r = −0.65). There was a strong negative correlation between pH and %E in soils enriched with metals in soluble form (e.g. metal salts, corrosion of galvanized structures). In soils where Cd or Zn were added in a less soluble form, no such correlation was found, and %E values were generally less than in soils spiked with metal salts, suggesting that the source of the contamination controls mainly the labile fractions of Cd and Zn.

Notes: The relative contributions of sources of carbon in soils, such as throughfall, litter, roots, microbial decay products and stable organic fractions, to dissolved organic C are controversial. To identify the origin of dissolved organic C, we made use of a 4-year experiment where spruce and beech, growing on an acidic loam and on a calcareous sand, were exposed to increased CO2 that was depleted in 13C. We traced the new C inputs from trees into dissolved organic C, into water-extractable organic C, and into several particle-size fractions. In addition, we incubated the labelled soils for 1 year and measured the production of dissolved organic C and CO2 from new and old soil C. In the soil solutions of the topsoil, the dissolved organic C contained only 5–10% new C from the trees. The δ13C values of dissolved organic C resembled those of C pools smaller than 50 µm, which strongly suggests that the major source of dissolved organic C was humified old C. Apparently, throughfall, fresh litter and roots made only minor contributions to dissolved organic C. Water-extractable organic C contained significantly larger fractions of new C than did the natural dissolved organic C (25–30%). The δ13C values of the water-extractable organic C were closely correlated with those of sand fractions, which consisted of little decomposed organic carbon. The different origin of dissolved and water-extractable organic C was also reflected in a significantly larger molar UV absorptivity and a smaller natural 13C abundance of dissolved organic C. This implies that the sampling method strongly influences the characteristics and sources of dissolved organic C. Incubation of soils showed that new soil C was preferentially respired as CO2 and only a small fraction of new C was leached as dissolved organic C. Our results suggest that dissolved organic C is produced during incomplete decomposition of recalcitrant native C in the soils, whereas easily degradable new components are rapidly consumed by microbes and thus make only a minor contribution to the dissolved C fraction.

Notes: In situ stabilization of heavy metals in contaminated soils by the addition of various types of soil amendment is an attractive technique for remediation. We investigated the potential of three industrial by-products (phosphogypsum, red gypsum and dolomitic residue) for boosting the heavy metal sorption capacity of an acid soil (patents pending, Spanish applications no 200201704 and 200201375) by using sorption isotherm experiments. The three by-products were found substantially to increase the retention of lead, cadmium and copper on the solid components of the soil. The increase in lead retention of the soil horizons upon the addition of both phosphogypsum and red gypsum was dominated by the formation of anglesite minerals. The dolomitic residue increased the metal retention capacity of the soil horizons through the precipitation of laurionite-type minerals as well as cadmium and copper hydroxy-chlorides. In addition to the batch sorption study, we used scanning electron microscopy to investigate the metal sorption processes in the soil by the effect of the treatments. Lead was frequently found to be linked to the edge charges of kaolinite minerals. The three metals were found to be associated with organic matter in the Ap horizon treated with the three by-products. Finally, the three metals were found to be associated with undissolved dolomitic residue particles.

Notes: Most methods for velocity macromodel estimation require considerable operator input, mainly concerning the regularization and the picking of events in the data set or in the migrated images. For both these aspects, slope tomography methods offer interesting solutions. They consider locally coherent events characterized by their slopes in the data cube. Picking is then much easier and consequently denser than in standard traveltime tomography. Stereotomography is the latest slope tomography method. In recent years it has been improved significantly, both from an algorithmic point of view and in terms of practical use. Robust and fast procedures are now available for 2D stereotomographic picking and optimization.Concerning the picking, we propose simple criteria for the selection of relevant data among the automatically picked events. This enables an accurate smooth velocity macromodel to be estimated quite rapidly and with very limited operator intervention. We demonstrate the method using a 2D line extracted from the Oseberg NH8906 data set.

Notes: The theme of the 2003 EAGE/SEG imaging workshop concerned the contrast between different philosophies of ‘model building’: whether an explicit, user-determined model should be imposed throughout the processing, with user updates at each step; or alternatively, whether user intervention should be kept to a minimum so as to avoid preconceived bias, and instead to allow the data itself to guide some heuristic process to converge to an optimal solution.Here we consider a North Sea study where our initial approach was to build the subsurface model using interpreted horizons as a guide to the velocity update. This is common practice in the North Sea, where the geology ‘lends itself’ to a layer-based model representation. In other words, we encourage preconceived bias, as we consider it to be a meaningful geological constraint on the solution.However, in this instance we had a thick chalk sequence, wherein the vertical compaction gradient changed subtly, in a way not readily discernible from the seismic reflection data. As a consequence, imposing the explicit top and bottom chalk horizons, with an intervening vertical compaction gradient (of the form v(x, y, z) =v0(x, y) +k(x, y).z), led to a misrepresentation of the subsurface.To address this issue, a gridded model building approach was also tried. This relied on dense continuous automatic picking of residual moveout in common-reflection point gathers at each iteration of the model update, followed by gridded tomography, resulting in a smoothly varying velocity field which was able to reveal the underlying local changes within the chalk.

Notes: In recent years, the advances in velocity model building and depth imaging have provided a better understanding of complex subsalt plays. The tomographic approach to subsurface velocity modelling, using interpretive processes, has led to significant progress in solving subsalt imaging problems, which were once considered to be impenetrable barriers. We show how gravity data, as an alternative data source, can be integrated into iterative velocity–depth model building to constrain the overburden velocity model and delineate the shape of the salt body above the target reflector. In this way, a structurally accurate image of subsalt reflectors is achieved.

Notes: A tomographic inversion method is presented that uses kinematic information in the form of zero-offset traveltimes and kinematic wavefield attributes (first and second spatial traveltime derivatives) to determine smooth, laterally inhomogeneous 3D subsurface velocity models for depth imaging. The kinematic wavefield attributes can be extracted from the seismic prestack data by means of the common reflection surface (CRS) stack. The input for the tomography is then taken from the resulting attribute volumes at a number of pick locations in the CRS stacked zero-offset volume. As a smooth model description based on B-splines is used and reflection points are treated independently of each other, only locally coherent events in the stacked volume are required and very few picks are needed. Thus, picking is considerably simplified.During the iterative inversion process, the required forward-modelled quantities are obtained by dynamic ray tracing along normal rays pertaining to the input data points. Fréchet derivatives for the tomographic matrix are calculated with ray perturbation theory. The inversion algorithm is demonstrated on a 3D synthetic data example, where the kinematic wavefield attributes have directly been obtained by forward modelling.

Notes: The use of the differential semblance misfit function on common-image-point gathers in the angle domain lends itself to an automated tomographic approach through a gradient-based search in the model space. The velocity model is described by a layer-based model with linear velocity trends and a superimposed bicubic B-spline. The interfaces of the layer-based model are computed by map migration of the PP zero-offset traveltimes of key reflectors. The common-image-point gathers are produced by a restricted inverse generalized Radon transform or amplitude-versus-angle-compensated migration. We present a complete description of all 2.5D formulae for isotropic velocity analysis of PP reflections and the results for ocean-bottom seismic data.

Notes: Seismic migration can be formulated in terms of two consecutive downward extrapolation steps: refocusing the receivers and refocusing the sources. Applying only the first focusing step with an estimate of the focusing operators results in a common focal point (CFP) gather for each depth point at a reflecting boundary. The CFP gathers, in combination with the estimates of the focusing operators, can be used in an iterative procedure to obtain the correct operators. However, current 3D seismic data acquisition geometries do not contain the dense spatial sampling required for calculation of full 3D CFP gathers. We report on the construction of full 3D CFP gathers using a non-full 3D acquisition geometry. The proposed method uses a reflector-orientated data infill procedure based on the azimuthal redundancy of the reflection data. The results on 3D numerical data in this paper show that full 3D CFP gathers, which are kinematically and dynamically correct for the target event, can be obtained. These gathers can be used for iterative updating of the 3D focusing operators.

Notes: We present a migration velocity analysis (MVA) method based on wavefield extrapolation. Similarly to conventional MVA, our method aims at iteratively improving the quality of the migrated image, as measured by the flatness of angle-domain common-image gathers (ADCIGs) over the aperture-angle axis. However, instead of inverting the depth errors measured in ADCIGs using ray-based tomography, we invert ‘image perturbations’ using a linearized wave-equation operator. This operator relates perturbations of the migrated image to perturbations of the migration velocity. We use prestack Stolt residual migration to define the image perturbations that maximize the focusing and flatness of ADCIGs.Our linearized operator relates slowness perturbations to image perturbations, based on a truncation of the Born scattering series to the first-order term. To avoid divergence of the inversion procedure when the velocity perturbations are too large for Born linearization of the wave equation, we do not invert directly the image perturbations obtained by residual migration, but a linearized version of the image perturbations. The linearized image perturbations are computed by a linearized prestack residual migration operator applied to the background image. We use numerical examples to illustrate how the backprojection of the linearized image perturbations, i.e. the gradient of our objective function, is well behaved, even in cases when backprojection of the original image perturbations would mislead the inversion and take it in the wrong direction.We demonstrate with simple synthetic examples that our method converges even when the initial velocity model is far from correct. In a companion paper, we illustrate the full potential of our method for estimating velocity anomalies under complex salt bodies.

Notes: A method is presented to estimate the elastic parameters and thickness of media that are locally laterally homogeneous using P-wave and vertically polarized shear-wave (SV-wave) data. This method is a ‘layer-stripping’ technique, and it uses many aspects of common focal point (CFP) technology. For each layer, a focusing operator is computed using a model of the elastic parameters with which a CFP gather can be constructed using the seismic data. Assuming local homogeneity, the resulting differential time shifts (DTSs) represent error in the model due to anisotropy and error in thickness. In the (τ−p) domain, DTSs are traveltimes Δτ that connect error in layer thickness z, vertical slowness q, and ray parameter p. Series expansion is used to linearize Δτ with respect to error in the elastic parameters and thickness, and least-squares inversion is used to update the model.For stability, joint inversion of P and SV data is employed and, as pure SV data are relatively rare, the use of mode-converted (PSV) data to represent SV in the joint inversion is proposed. Analytic and synthetic examples are used to demonstrate the utility and practicality of this inversion.

Notes: An integrated multiscale seismic imaging flow is applied to dense onshore wide-aperture seismic data recorded in a complex geological setting (thrust belt).An initial P-wave velocity macromodel is first developed by first-arrival traveltime tomography. This model is used as an initial guess for subsequent full-waveform tomography, which leads to greatly improved spatial resolution of the P-wave velocity model. However, the application of full-waveform tomography to the high-frequency part of the source bandwidth is difficult, due to the non-linearity of this kind of method. Moreover, it is computationally expensive at high frequencies since a finite-difference method is used to model the wave propagation. Hence, full-waveform tomography was complemented by asymptotic prestack depth migration to process the full-source bandwidth and develop a sharp image of the short wavelengths. The final traveltime tomography model and two smoothed versions of the final full-waveform tomography model were used as a macromodel for the prestack depth migration.In this study, wide-aperture multifold seismic data are used. After specific preprocessing of the data, 16 frequency components ranging from 5.4 Hz to 20 Hz were inverted in cascade by the full-waveform tomography algorithm. The full-waveform tomography successfully imaged SW-dipping structures previously identified as high-resistivity bodies. The relevance of the full-waveform tomography models is demonstrated locally by comparison with a coincident vertical seismic profiling (VSP) log available on the profile. The prestack depth-migrated images, inferred from the traveltime, and the smoothed full-waveform tomography macromodels are shown to be, on the whole, consistent with the final full-waveform tomography model. A more detailed analysis, based on common-image gather computations, and local comparison with the VSP log revealed that the most accurate migrated sections are those obtained from the full-waveform tomography macromodels. A resolution analysis suggests that the asymptotic prestack depth migration successfully migrated the wide-aperture components of the data, allowing medium wavelengths in addition to the short wavelengths of the structure to be imaged.The processing flow that we applied to dense wide-aperture seismic data is shown to provide a promising approach, complementary to more classical seismic reflection data processing, to quantitative imaging of complex geological structures.

Notes: Three models for the dynamics of seismic airgun-generated bubbles and their associated far-field signals are developed and compared with geophysical data. The first model of an airgun-generated bubble uses a spherical approximation, the second is an approximate Lagrangian model which allows for small deformations from a spherical shape, whilst the final model is an axisymmetric boundary-integral method which permits the bubble to evolve into highly non-spherical geometries. The boundary-integral method also allows both geometric interference and strong dynamic interactions in multi-bubble studies.When comparing the spherical model to experimental data there are three apparent, significant differences: the magnitude of the primary pressure peak, which is greater in the model; the subsequent decay of the pressure peaks and motion – the experimental data demonstrating greater decay and a slower rise rate; and the frequency of oscillation, which is slower in the experimental data. It is believed that the first discrepancy is due to the initial stages of expansion where the compressed air is forced to sparge through the airgun ports. The other differences indicate that there is some other energy-loss mechanism which is not accounted for in the spherical bubble model. Non-spherical bubble behaviour is investigated through the use of two different deformable many-bubble codes and their predictions are compared with the spherical model and experimental data.The Lagrangian model predicts the formation of a buoyancy-driven liquid jet on the first collapse of a typical airgun bubble; however, the model breaks down when the bubble becomes significantly deformed, due to a low-order spherical-harmonic approximation for the potential. The axisymmetric boundary-integral code models the jet shape accurately and it is found that these bubbles evolve to toroidal geometries when the jet impacts on the opposite surface of the bubble. This highly non-spherical behaviour is readily observed on high-speed films of airgun bubbles, and is one key source of energy loss; it damps the pulsations of the bubble and slows its rise speed.Inter-bubble interactions are investigated using the two deformable bubble models, and the predictions are compared to field data. It was found that as the bubbles approach each other, their periods of oscillation increase in accordance with observations, and jets are formed in the direction of motion upon collapse.

Notes: Articles 3·3 and 3·4 of the Kyoto protocol provide Annex I countries the possibility to reduce greenhouse gas emissions through the sequestration of carbon (C) in their terrestrial ecosystems. For such accounting, the 1990 flux is needed and, therefore, a correct knowledge of the baseline (1990) C stocks is necessary. In addition, a correct methodology should be used to investigate the capacity of ecosystems to sequester C through changes in land use or management by the end of the first commitment period (2008–2012). At national and regional scales, formulation of baseline C stocks in terrestrial ecosystems is difficult and uncertain. Differences in method of analysis, sampling depth of soil, lack of sufficient C data and the necessity to extrapolate C data to total soil organic C stocks, provide problems when comparing databases with each other. In this study, three extrapolation models were compared with the classical layer-based method to determine the model with the best fit. The model with the best predictions, in relation to the classical layer-based model, uses recent soil C profiles for estimating the parameter k, which represents the decrease in the proportion of soil organic C with depth, and for extrapolating the C data available for 1990 and 2000 to a depth of 1 m. The other two models gave large underestimates.

Notes: The nutritive value of berseem clover (Trifolium alexandrinum L.) may be influenced by changes in the nutrient concentrations of morphological fractions as a consequence of cutting treatment. The aim of this study was to evaluate the effects of different cutting treatments on the nutritive value of herbage and leaf and stem components in two Mediterranean berseem genotypes during growth in order to develop management approaches for harvesting forage with a high nutritive value. Spring growth of genotypes of Egyptian (cv. Giza 10) and Italian (cv. Sacromonte) origins was harvested in each of 2 years beginning 196 days after sowing and thereafter every 6 days (twelve harvests in total) to measure dry matter (DM) yield and nutritive value. Cutting treatments were initiated at sixth internode elongation (A) and early flowering (B) and there was an uncut control treatment (C). In vitro digestibility of organic matter (IVOMD) and crude protein (CP) concentration were determined for leaf, stem and total forage of each cultivar at each harvest. For both cultivars, in the uncut treatment (C), DM yield increased linearly to a maximum of 14 800 kg ha−1, on average, by 250 days after planting, the same time at which stem DM accumulation peaked, whereas the nutritive value, in terms of IVOMD and CP concentration, declined with age, coinciding with a reduction in leaf:stem ratio (LSR) from 1·00 to 0·30. Plant parts differed (P 〈 0·01) in nutritive value with stems being of lower nutritive value than leaves, in the two cutting treatments. There were strong positive correlations between LSR and herbage IVOMD and CP concentration, in both cutting treatments, indicating that, during growth, part of the changes in IVOMD and CP concentration of berseem clover plants was due primarily to the changes in the LSR. Defoliation induced a considerable reduction in DM yield, but an increase in the LSR and a small increase in nutritive value. Plants cut at the sixth internode elongation (A) showed a small proportional decrease (0·19) in total DM yield, but higher LSR values and similar or higher IVOMD and CP concentration than initiating cutting at early flower (B). Delaying defoliation to the early flowering stage (B) increased the proportion of stems and, therefore, decreased nutritive value. Therefore, harvest management in which cuts are applied at the stage of sixth internode elongation appears to be the most favourable for obtaining relatively high yields of forage with high nutritive value in berseem clover grown in Mediterranean regions.

Notes: Turf quality is a complex character of fundamental importance in turfgrass evaluation. It takes into account aesthetic and functional aspects, and depends on several individual components which may vary with time. The use of a synthetic and simple quality score is necessary when evaluating large numbers of varieties. The quality of 110 turfgrass varieties belonging to four species (Lolium perenne, Poa pratensis, Festuca arundinacea and F. rubra) was assessed in the second and third years of growth at three Italian locations, i.e. Lodi (Po Valley, continental climate), Perugia (central Italy, sub-Mediterranean climate) and Foggia (southern Italy, Mediterranean climate), using a visual score ranging from 9 (outstanding turf) to 1 (very poor turf). A randomized block design with three replicates was used, with varieties of the same species being blocked to facilitate the comparison within species. On average, F. rubra had the lowest turf quality score in summer, whereas the other species had the lowest quality score in winter and the highest quality score in summer and autumn. Components of variance were large for genotype (i.e. variety) main effects in all species. A variety × location interaction was found in F. arundinacea and higher-order interactions were also found for P. pratensis and F. rubra. Genotype × environment effects were small relative to genotypic effects in L. perenne. Variety × year interactions were small in all cases, whereas variety × location and variety × season interactions were greater. Stability of turf quality across sites, seasons and years was measured for each variety in terms of environmental variance, i.e. the variance of score values across sites, years and seasons. Mean scores and stability values of varieties were integrated into an index of reliability that estimated the lowest score value expected in 0·80 of cases. For each species, a small subset of highly reliable varieties could be identified. Implications of the results for the testing and breeding of varieties in Italy are discussed.

Notes: Moisture and treading treatments were imposed on intact turves that were relocated to a glasshouse after being removed from three hill pastures of different soil fertility in the North Island of New Zealand. The experiment consisted of a 2-month stress phase, where the treatments were wetting (W), wetting and treading (WT), drying (D) and control (C). In this phase, herbage accumulation rate, tiller density and leaf extension rate were lower on the D turves, and herbage accumulation rate and tiller density were lower on the WT turves than for the C turves. Herbage accumulation rate was higher on the W treatment than on the C treatment.In the 2-month recovery phase, herbage accumulation rate and leaf extension rate on the D turves were higher than those of the C treatment. Herbage accumulation rate and tiller density took longer to recover on the WT turves but by the end of the recovery period tiller density on these turves exceeded that of the C turves and the original tiller densities on the WT turves. Changes (increase or decrease) in leaf extension rate were associated with the W treatment and tiller density with the WT treatment. Moisture was limiting on the D and C turves, but on the W and WT turves, where moisture was adequate for plant growth, nutrients were limiting, notably phosphorus on the W and WT turves and sulphur on the W turves.The D treatment turves recovered very quickly once the stress was removed but the WT turves were slower to recover. Under the experimental conditions applied, the hill pasture turves were more resilient to the drying treatment than the wetting and treading treatment.

Notes: The grazing behaviour by sheep, after the loss of the temporary incisors and before their replacement with the permanent incisors, was compared with that after the first pair of permanent incisors had completely developed in grazing experiments, conducted from June to September 2001, with three Suffolk castrated male sheep, born in late-March 2000. A new method was developed to investigate bite mass and bite force, using hand-constructed swards, which were composed of groups of four (4L), eight (8L), twelve (12L), sixteen (16L) and twenty (20L) leaves of cocksfoot (Dactylis glomerata) arranged 15 cm apart. Each group of leaves was attached to a separate three-directional load cell.The period of time between loss of temporary incisors and the complete eruption of permanent incisors was c. 1 month. The number of bites per group of leaves increased with increasing leaf density. The number of bites per group of leaves was higher after the loss of temporary incisors than with the permanent incisors. The number of leaves per bite and dry-matter (DM) intake per bite were almost twice as great with permanent incisors than after the loss of temporary incisors; DM intakes per bite force were 3·9–4·9 mg N−1 and 1·7–2·6 mg N−1 respectively. After the loss of temporary incisors, the proportion of forward-direction forces accounted for 0·805 of the forces in the 4L treatment and 0·155–0·317 of the forces in the 8L–20L treatments. In contrast, the proportion of forward-direction forces accounted for only 0·292 in the 4L treatment and 0·026–0·163 in the 8L–20L treatments with permanent incisors. The angles of bite forces were almost the same (54·7–56·3°) when sheep used a forward direction, and were 51·3–57·3° when sheep used a backward direction.

Notes: In Mediterranean areas, the establishment of multi-species pastures for extensive livestock use is an alternative to the growing of traditional cereal crops. Lolium rigidum Gaud. is one of the most valuable forage grasses adapted to semiarid environments but its performance in mixtures is not fully understood. Field observations suggest that the species exerts allelopathic effects, although there is no evidence in the literature to support this assumption. The objective of the study was to determine whether L. rigidum affects the germination and seedling growth of common forage species by allelopathic means. Two bioassays were conducted to test for the allelopathic potential of seeds and adult (shoot and root) tissues of L. rigidum on two grasses, Lolium multiflorum Lam. and Dactylis glomerata L., and a legume, Medicago sativa L. The three species showed different degrees of sensitivity to L. rigidum with L. multiflorum being particularly sensitive to allelopathy. Positive and negative effects of L. rigidum on seedling development were noted. Shoot extracts of L. rigidum displayed the most consistent negative effects by inhibiting elongation of the radicle of the three target species. The significance of the results is that in drought-prone environments and where water resources are scarce poor root development decreases the ability of the plants to grow and survive.

Notes: The effects of elevated atmospheric carbon dioxide (CO2) concentration (700 μmol mol−1) on defoliated (three clippings at 3-week intervals) and undefoliated plants were determined for the C4 grass Themeda triandra, Forsk. The elevated CO2 concentration significantly increased leaf regrowth following defoliation, and total leaf production was greatest in this treatment. Shoot biomass of undefoliated plants was also increased under the elevated CO2 concentration treatment. The primary effect of the elevated CO2 concentration in both defoliated and undefoliated plants was an increase in individual leaf length and mass of dry matter, linked to a higher leaf water content and increased photosynthetic rates at the canopy level. Photosynthetic down-regulation at the leaf level occurred, but this was compensated for by increased assimilation rates and greater canopy leaf area at the elevated CO2 concentration. Increases in leaf and sheath growth of defoliated plants in the elevated CO2 concentration treatment were lost following a final 3-week reversion to ambient CO2 concentration, but occurred in plants exposed to the elevated CO2 concentration for the final 3-week period only. In conclusion, elevated atmospheric CO2 concentration increases shoot growth via increased leaf extension, which is directly dependent on stimulation of concurrent photosynthesis. CO2 responsiveness is sustained following moderate defoliation but is reduced when plants experience reduced vigour as a result of maturation or high frequency of defoliation.

Notes: The effects of rate of inorganic nitrogen (N) fertilization (0, 80 or 160 kg N ha−1 per regrowth), season of harvest (regrowths 1, 2 and 3) and perennial ryegrass (Lolium perenne L.) cultivar [classified as having either a normal or elevated water soluble carbohydrate (WSC) concentration genotype] on in vitro gas production and digestibility were assessed. Increased N fertilizer application significantly decreased total gas production (TGP), methane (CH4) production and organic matter digestibility (OMD). The results suggest that the decreases in TGP and CH4 production were associated with a restriction in organic matter (OM) fermentation and an altered crude protein (CP) to structural carbohydrate ratio rather than a modification in the stoichiometry of fermentation. Season of harvest only significantly (P 〈 0·05) altered in vitro OMD and CH4 production at 8 h, despite altering the chemical composition of the herbage. Cultivar effects on all measured in vitro parameters were not significant presumably because the elevated WSC concentration trait was not expressed strongly in the study.

Notes: Three cultivars (two diploid and one tetraploid) in each of three maturity groups (early, intermediate and late) of perennial ryegrass were sown in 10 m2 plots, replicated four times, in Northern Ireland in June 1997 in a study of the effect of heading date on tiller development (including initiation to flower) and turnover of tillers produced at specific times in spring in 1998 and 1999. The plots were harvested seven times in each year. Annual dry-matter production was similar for all groups in each year. In spring and early summer of both years, tiller density of the diploid cultivars was 1·5 times greater than that of the tetraploid cultivars and the mean tiller density over all swards in June was about 0·40 times greater than that in April. Maximum proportions of reproductive tillers in the early, intermediate and late maturity groups, determined from apical dissections, were found in early April, mid-May and early June, respectively. Although a high proportion of tillers, which were present when annual observations commenced in spring, was decapitated at the first harvest in the early group, the previous population density was maintained by rapid production of new tillers during May, including those from suppressed tiller buds during reproduction.It is concluded that the relationship between heading date and rate of tiller turnover (including flowering) at specified times in spring is important in sward management throughout the early part of the growing season and should be taken into account in tiller-based grass growth models.

Notes: A partitioning of the total variance in species composition of grasslands associated with increasing fertilizer inputs (unfertilized pastures, artificially fertilized hay meadows and intensively cultivated grassland) in western Norway was undertaken. The partitioning was carried out with (partial) constrained ordinations (canonical correspondence analysis) and associated Monte Carlo permutation tests. Explained variation was high (0·651), with soil chemistry, management and site explaining 0·271, 0·228 and 0·052 of the variation, respectively, and the interaction between soil and management explaining 0·100 of the variation. However, much of the measured soil chemistry was considered to be an effect of management. The soil chemistry variable explaining most variation was extractable P content, associated with high soil extractable P contents in the intensively cultivated grassland due to high fertilizer applications. However, soil extractable P content did not explain differences in species composition when grasslands with smaller differences in fertilizer inputs (meadows vs. pastures) were compared. Total soil C and N contents and C:N ratios explained significant variation between all grassland types. Lowest levels of these variables were measured in the grassland with the highest fertilizer inputs, suggesting that total soil N content cannot be used as a predictor of fertility. Significantly higher soil N contents were measured in grasslands of low productivity, probably due to a low decomposition rate of stress-tolerant plants and the consequent low availability of soil N and accumulation of soil organic matter. Ellenberg N values reflected soil chemical differences in this study with high Ellenberg N values reflecting high Ca, Mg and P contents and pH values and low total C and N contents and C:N ratios.

Notes: To determine the impacts of climate change and defoliation on the community structure and plant diversity of a semi-natural temperate grassland, monoliths of a permanent grassland were exposed to ambient or elevated atmospheric CO2 concentrations (ambient + 235 ppmv) and temperature (ambient + 3°C) from October 1998 to December 2000. The monoliths were subjected to two different cutting frequencies, either two or six cuts per year. The grassland community structure changed during the course of the experiment and was more responsive to changes in management than to changes in climate. Increased cutting frequency stimulated plant diversity by enhancing the number of forb species, but plant diversity was not significantly affected by climate change. The contribution of individual plant species to the vegetation cover revealed species-specific responses to climate change and cutting frequency, but for most species significant interactions between climate change and cutting frequency were present. There were no clear-cut effects of treatments on the total annual yield and the proportion of forbs present, as significant interactions between climate change and cutting frequency occurred. It is concluded that differential grassland management will modify plant species-specific responses to climate change and resulting changes in the botanical composition of mixed-species, temperate grasslands.

Notes: A field experiment was conducted over a 4-year period to determine NO3 leaching losses from grassland on a freely draining sandy soil. The experiment consisted of all combinations of five defoliation systems; cutting-only (CO), rotational grazing (GO), mixed systems with one (MSI) or two silage cuts (MSII) plus subsequent rotational grazing, and simulated grazing (SG), four mineral nitrogen (N) application rates (0, 100, 200, and 300 kg N ha−1 year−1), and two slurry levels (0 and 20 m3 slurry ha−1 year−1). Due to the high N return by grazing animals, leaching losses in the rotational grazing systems generally were associated with NO3-N concentrations which exceeded the EU limit for drinking water. NO3 leaching losses in a rotational grazing system could be reduced by lowering the N fertilizer intensity and the inclusion of one or two silage cuts in spring. However, even in the unfertilized mixed systems, N fixation by white clover exceeded the amounts of N removed via animal products, which resulted in NO3-N concentrations well above the EU limit for drinking water. In terms of leaching losses, the cutting-only system was the most advantageous treatment. NO3 leaching losses on grassland could be predicted by the amount of soil mineral N at the end of the growing season and by the N surplus calculated from N balances at the field scale. From the results obtained a revised nitrogen fertilization policy and a reduced grazing intensity by integrating silage cuts are suggested.

Notes: Grassland and its management is central to the productivity of and nitrogen (N) losses from dairy farms in north-west Europe. Botanical composition, production and N surplus of grassland were assessed during five consecutive years. The experiment consisted of all combinations of five defoliation systems: cutting-only (CO), rotational grazing (GO), grazing + one (MSI) or two silage cuts (MSII) and simulated grazing (SG). Four mineral N fertilization rates (0–300 kg N ha−1 year−1) and two slurry levels (0 and 20 m3 slurry ha−1 year−1) were applied. Fertilizer N was more efficient in producing net energy (NEL) in grazing-dominated, low white clover systems (GO and MSI systems: 70 and 88 MJ NEL kg−1 N) than in white clover-rich systems (MSII, CO and SG systems: ≤60 MJ NEL kg−1 N). While sward productivity in system MSI was similar to that in system GO, system MSII benefited from increased N2 fixation at low N rates. There were small differences in NEL concentrations of the herbage between defoliation systems. Crude protein concentration of the herbage increased with increasing N supply from fertilizer, excreta and N2 fixation. N surpluses (−63 to +369 kg N ha−1 year−1) increased with increasing grazing intensity and increasing N fertilization rate. The average response in N surplus applied was 0·81, 0·59, 0·40, 0·33 and 0·24 kg N ha−1 in systems GO, MSI, MSII, CO and SG respectively.

Notes: Interspecific hybrids between white clover (Trifolium repens L.) and Caucasian clover (Trifolium ambiguum M. Bieb.) have been developed to introgress the rhizomatous growth habit into white clover, to increase persistence and drought tolerance. The forage quality of T. repens, T. ambiguum and the backcross 1 (BC1) and backcross 2 (BC2) hybrids and companion grass, when grown in mixtures with an intermediate perennial ryegrass (Lolium perenne L.) under a cutting-only management, was measured. In vitro dry-matter digestibility (DMD), water-soluble carbohydrate (WSC) and crude protein (CP) concentrations of the legume and grass fractions were measured throughout the growing season over three harvest years. Trifolium repens had a lower WSC but a higher CP concentration than the perennial ryegrass companion in all harvest years and at all cuts. The legume fractions from the BC1 and BC2 hybrid plots had a higher WSC and a lower CP concentration but an in vitro DMD value comparable with white clover throughout the growing season and in each harvest year. The grass fractions from the mixtures with the backcross hybrids had a higher WSC and a lower CP concentration than the grass fraction from the T. repens plots, in all harvest years and throughout the growing season. No difference in in vitro DMD between parental species and backcross hybrids was observed. The implications of these results for the development of these hybrids and animal performance are discussed.

Notes: Complex spatial variation in soil can be analysed by wavelets into contributions at several scales or resolutions. The first applications were to data recorded at regular intervals in one dimension, i.e. on transects. The theory extends readily to two dimensions, but the application to small sets of gridded data such as one is likely to have from a soil survey requires special adaptation. This paper describes the extension of wavelet theory to two dimensions. The adaptation of the wavelet filters near the limits of a region that was successful in one dimension proved unsuitable in two dimensions. We therefore had to pad the data out symmetrically beyond the limits to minimize edge effects.With the above modifications and Daubechies's wavelet with two vanishing moments the analysis is applied to soil thickness, slope gradient, and direct solar beam radiation at the land surface recorded at 100-m intervals on a 60 × 101 square grid in south-west England. The analysis revealed contributions to the variance at several scales and for different directions and correlations between the variables that were not evident in maps of the original data. In particular, it showed how the thickness of the soil increasingly matches the geological structure with increasing dilation of the wavelet, this relationship being local to the strongly aligned outcrops. The analysis reveals a similar pattern in slope gradient, and a negative correlation with soil thickness, most clearly evident at the coarser scales. The solar beam radiation integrates slope gradient and azimuth, and the analysis emphasizes the relations with topography at the various spatial scales and reveals additional effects of aspect on soil thickness.

Notes: The general linear model encompasses statistical methods such as regression and analysis of variance (anova) which are commonly used by soil scientists. The standard ordinary least squares (OLS) method for estimating the parameters of the general linear model is a design-based method that requires that the data have been collected according to an appropriate randomized sample design. Soil data are often obtained by systematic sampling on transects or grids, so OLS methods are not appropriate.Parameters of the general linear model can be estimated from systematically sampled data by model-based methods. Parameters of a model of the covariance structure of the error are estimated, then used to estimate the remaining parameters of the model with known variance. Residual maximum likelihood (REML) is the best way to estimate the variance parameters since it is unbiased. We present the REML solution to this problem. We then demonstrate how REML can be used to estimate parameters for regression and anova-type models using data from two systematic surveys of soil.We compare an efficient, gradient-based implementation of REML (ASReml) with an implementation that uses simulated annealing. In general the results were very similar; where they differed the error covariance model had a spherical variogram function which can have local optima in its likelihood function. The simulated annealing results were better than the gradient method in this case because simulated annealing is good at escaping local optima.

Notes: Earthworms play an important role in protecting carbon in the soil, but the exact influence of their activity on the distribution and protection of C is still poorly understood. We investigated the effect of earthworms on the formation of stable microaggregates inside newly formed macroaggregates and the distribution of C in them. We crushed (〈 250 µm) soil, and subjected it to three treatments: (i) soil + 13C-labelled residue + earthworms (these added after 8 days' incubation), (ii) soil + 13C-labelled residue, and (iii) control (no additions), and then incubated it for 20 days. At the end, we measured the aggregate size distribution, total C and 13C, and we isolated microaggregates (53–250 µm) from macroaggregates (〉 250 µm) formed. The 13C in fine particulate organic matter between and within the microaggregates was determined. Earthworms helped to form large macroaggregates (〉 2000 µm). These large macroaggregates contained four times more stable microaggregates than those from samples without earthworms. There was more particulate organic matter within and between microaggregates in macroaggregates in the presence of earthworms. The larger amounts of organic matter inside stable microaggregates in casts than in bulk soil after 12 days of incubation (140 mg 13C kg−1 soil compared with 20 mg 13C kg−1 soil) indicates that these microaggregates are formed rapidly around freshly incorporated residues within casts. In conclusion, earthworms have a direct impact on the formation of stable microaggregates and the incorporation of organic matter inside these microaggregates, and it seems likely that their activity is of great significance for the long-term stabilization of organic matter in soils.

Notes: Despite widespread bench terracing of rainfed hillsides in upland West Java, soil loss rates remain high. This paper reports measurements of sediment yield from terrace risers and beds and from terrace units made during three consecutive rainy seasons. The results demonstrate that soil loss from the terraces occurs in two stages: rainfall-driven transport by splash and shallow overland flow (wash) from the terrace riser and bed to a central drain is followed by a combination of onward wash transport of fine sediment and entrainment by runoff of coarser sediment deposited in the drain. A model (TEST: Terrace Erosion and Sediment Transport) was developed, describing these processes as a function of vegetation and soil surface cover and the presence of a layer of deposited sediment. The model was calibrated using some of the measured sediment yield data and subsequently tested by simulating the remaining data. The results were satisfactory and modelled fractions of sediment transported by splash, wash and flow-driven runoff transport generally compared well with observed fractions of fine and coarse particles in eroded sediment from the various plots.

Notes: In some soils, aggregate coatings and walls of biopores differ in the content of clay and organic carbon from that of the aggregate interiors or the soil matrix. The composition of the organic matter on aggregates and on the surfaces of biopores is largely unknown. We have compared the composition of organic matter between inner and outer parts of aggregates and between biopore walls and the soil matrix in a loamy arable soil and a sandy forest one. Hot-water- and sodium-pyrophosphate-extractable organic matter was analysed by Fourier transform infrared (FT-IR) spectroscopy. For the sandy forest soil, the FT-IR spectra showed that organic matter from the walls of root channels contains fewer functional groups with absorption bands at 1740–1710 cm−1 and 1640–1600 cm−1 than that from burrow fillings. For the arable soil, the content of these functional groups in hot-water-soluble organic matter from the coatings is less than in that from the interiors in the topsoil, and the reverse is so in the subsoil, probably because water-soluble organic matter containing these functional groups has moved from topsoil to subsoil. The results indicate that root channels in the forest soil have more reactive zones in an otherwise relatively inert sandy matrix, whereas aggregate coatings in the arable subsoil have a greater cation exchange capacity and a greater sorption potential for hydrophobic substances than the aggregate interiors.

Notes: Bhutan lies at altitudes of 100–7500 m on the steep, long and complex southern slopes of the Eastern Himalayas. Soil surveys show that, despite steep gradients, there are many moderately or deeply weathered soils. Many slopes are mantled with polycyclic, layered drift materials, so soil horizons owe as much to regolith heterogeneity as to pedogenesis. In the limited arable areas soil profiles are further complicated by rice cultivation and the construction, maintenance and irrigation of flat terraces on steep slopes. Some natural pedogenic horizonation is apparent, and there is an altitudinal zonation of soil types. Although the climate is warm and seasonally wet, most soils on the subtropical southern foothills are not particularly weathered and leached. The foothills are seismically active, and many soils are formed in unstable landslide debris. Elsewhere the regoliths are more stable. The main soils up to about 3000 m in the inner valleys are moderately weathered and leached, and have bright subsoil colours and thin dark topsoils. Above these there is a zone of bright orange-coloured non-volcanic andosolic soils. Further upslope there are acid soils with thick surface litter, stagnogleyic topsoils, and drab brown subsoils with organic cutans. These grade to weak podzols, which extend from about 3500 m up to the treeline, around 4000 m. Above this, alpine turf soils, with deep, dark, and friable topsoils and yellowish friable subsoils, are intermixed with unweathered glacial deposits. The interactions between pedogenesis and the deposition of the varied and layered drift materials complicate mapping and classification of the soils.

Notes: The post-war decline in the area and diversity of neutral meadows in Britain, resulting from agricultural intensification, has prompted schemes to restore and create new habitats. Their success relies on understanding the relations between soil fertility and species diversity. We have investigated these relations, using multivariate analysis, in 28 semi-natural meadows and eight artificially created urban meadows. Mineralizable nitrogen was the most important soil characteristic in the semi-natural sites; the more N the soil contained the fewer were the species characteristic of traditional meadows. Both potassium and total magnesium favoured diversity, perhaps because their deficiency in many traditionally managed meadows jeopardizes the survival of broad-leaved species in competition with grasses. Available lead, at sub-lethal concentrations and measured as a Pb:Ca ratio, appeared to favour diversity in the semi-natural sites, possibly by inhibiting the uptake of P by competitive grasses and allowing the less competitive species associated with diversity to flourish. The main differences between the soils of the artificial and the semi-natural meadows were that the former contained more extractable P and less mineralizable N and organic matter. It seems that large soil phosphorus concentrations may be the main reason why relatively few species colonize or survive in grassland on many urban soils.

Notes: Knowledge of thermal conductivity of granular materials under reduced air pressure can be utilized for studying intricate mechanisms of heat transfer in two-phase systems. We measured the thermal conductivity of three soils of varied texture and two sets of glass beads (GB) under reduced air pressure using a twin heat probe. We also predicted the thermal conductivity of a two-phase system at reduced air pressure from the modified Woodside & Messmer equation based on the kinetic theory of gases. This equation includes a thermal separation of solid particles (d) defined by the heat conduction. We compared this separation with the geometrical mean separation of solid particles (D). The results showed a linear relation between d and D for the GB, and in all cases d was smaller than D. This suggests that conductive heat transfer in two-phase GB takes place mainly through air spaces the dimension of which is smaller than D.The d of a Red Yellow soil and an Ando soil, however, were about 200–300 times larger than D. This result seems to be related to the soil aggregation. We showed that in soil aggregates the conduction of heat through the solid was the dominant mode of heat transfer, and the micropores in a soil aggregate had very little effect on the diminished thermal conductivity under reduced air pressure. The decrease in the thermal conductivity of two-phase soil under reduced air pressure is probably caused by the air molecules confined in interaggregate pore spaces rather than those in the intra-aggregate pore spaces. The d of soils can be used to represent the thermal separation of the interaggregate pore spaces, and soil aggregates can be treated as single-grained particles in evaluating heat conduction.

Notes: Inorganic and organic soil colloids are responsible for the sorption of many pesticides. We studied the sorption of the herbicide primisulfuron [methyl 2 N-[[[[[4,6-bis(difluoromethoxy)-2-pyrimidinyl]amino]carbonyl]amino]sulfonyl]benzoate] on Fe3+-, Al3+-, Ca2+- and Na+-exchanged montmorillonite, soil organic matter (H+- and Ca2+-saturated), amorphous iron oxide, and three soils in aqueous media. The sorption on soils was negatively correlated with pH. Ca2+- and Na+-exchanged montmorillonites are ineffective in the sorption of primisulfuron. The sorption on Fe3+- and Al3+-exchanged montmorillonite is rapid and follows the Freundlich equation. Fourier transform infrared (FT-IR) and X-ray powder diffraction studies of the Fe3+- and Al3+-montmorillonite samples after the interaction with primisulfuron in chloroform solution suggest that primisulfuron is adsorbed and degraded in the interlayer. Humic acid is more effective in the sorption than is Ca humate, suggesting that the pH of the suspension (3.5 for humic acid and 6.0 for Ca humate) has a strong influence on the sorption of primisulfuron. Experiments on amorphous iron oxide indicate similar pH dependence. Infrared spectra indicate that the protonation of the pyrimidine nitrogen moiety of herbicide and subsequent hydrogen bonding with the surface hydroxyls of Fe oxide is the mechanism acting in the primisulfuron sorption.

Notes: A simple method for measuring tiller volume of grasses is described. The equipment, based on the communicant pipe principle, was built using a PVC pipe linked to a laboratory volumetric pipette. The results showed a high degree of consistency and were similar to empirical results published in the literature, indicating that tiller volume of grasses can be easily measured with this technique.

Notes: Low rates of herbage dry matter (DM) intake impose limits on total daily DM intake in grazing dairy cows. The objective of this study was to increase total daily DM intake and milk production by restricting daily time available for grazing (TAG) and replacing it with time available for eating a maize silage/soyabean meal (TAMS) diet indoors. The treatments (TAG + TAMS) were 20 + 0, 19 + 1, 10 + 10 and 5 + 15 h. Measurements were made of milk production, intake and feeding behaviour. The interactions of TAG + TAMS treatments with sward height (SH) and concentrate level (CL) were also examined. Two experiments, each lasting 42 days, were carried out in spring (Experiment 1) and autumn (Experiment 2) using forty-eight and twenty-four Holstein-Friesian cows respectively. Treatments were arranged in a factorial design with TAG + TAMS treatments, SH (Experiment 1 only) and CL as the independent variables and a TAG + TAMS of 20 h. Reducing TAG and increasing TAMS significantly reduced estimated herbage DM intake and significantly increased maize silage/soyabean meal intake in both experiments, but there were no significant main effects of TAG + TAMS treatments on milk yield (mean, 27·4 and 25·5 kg d−1 for Experiments 1 and 2 respectively), and yield of milk constituents. Increasing SH (Experiment 1) and CL (Experiments 1 and 2) significantly increased milk yield. In Experiment 1, there was a significant interaction between TAG + TAMS treatments and SH with the taller sward height of 8–10 cm and the 20 + 0 treatment having the highest milk yield (29·7 kg d−1) and the 5 + 15 treatment the lowest (27·2 kg d−1), whereas at the lower sward height of 4–6 cm, milk yield was lowest on the 20 + 0 treatment (25·5 kg d−1) with the other three treatments being higher (mean, 26·9 kg d−1). Replacing TAG with TAMS significantly increased liveweight gain in Experiment 1 but not in Experiment 2. Estimated rates of intake of herbage were lower in the autumn experiment (Experiment 2, 9·6 g DM min −1) than in the spring experiment (Experiment 1, 29·4 g DM min −1) but rates of intake of maize silage were higher in the autumn (112·4 g DM min−1) than in the spring (72·5 g DM min−1). In conclusion, in spring the response to replacing TAG with TAMS was dependent on sward conditions with the highest milk fat plus protein yield being on the 20 + 0 treatment at the high sward height and on the 19 + 1 treatment at the low sward height. The high liveweight gain of the 5 + 15 treatment could be an important means of restoring body condition in grazing lactating cows. In autumn, intakes of herbage were low in spite of its high estimated nutritive value with all treatments having a similar level of performance.

Notes: Plots of five intermediate-heading varieties of perennial ryegrass (Lolium perenne L.) [AberDove, Belramo and Glen (diploid); Twins (tetraploid); and AberExcel (tetraploid hybrid)] were continuously stocked with sheep to maintain a target sward surface height of 40–50 mm. Daily dry matter (DM) intake was significantly different (F-value = 0·032) between the varieties, with the tetraploid hybrid AberExcel having the highest values for daily DM intake and intake rate during eating. Amongst the diploid varieties, intake rate tended to be higher for sheep grazing Glen. The varieties comprised a wide range in potential growth habit, from the relatively prostrate, highly tillered Glen to the more-erect AberExcel and there were differences between them in the vertical distribution of leaves within the sward canopy. The leaves of AberExcel weighed 3·6 mg DM cm−2 leaf area in contrast to the other varieties (4·3–5·3 mg DM cm−2 leaf area) resulting in a high leaf area index (LAI) in relation to the green leaf mass. Intake rate was not significantly correlated with extended tiller and sheath tube lengths, partition of herbage mass, number of tillers per square metre or LAI. However, canonical variates analysis showed that there were significant differences between the varieties for the morphological and chemical factors examined. Other factors also need to be explored to explain these differences in ingestive behaviour in order to identify plant traits that are correlated with herbage intake rate. These are needed for varieties destined for grazing use, both during the breeding programme and their subsequent evaluation.

Notes: Current policies for upland pasture management in the UK encourage the integration of environmental objectives with livestock production through extensification of grazing systems. This study tested the hypothesis that a greater sward height in the summer would increase the diversity and abundance of grassland beetles (Coleoptera) as has been demonstrated for insects of indigenous grasslands.The hypothesis was tested with an experiment on an upland sheep pasture in mid-Wales. Experimental treatments received different nitrogen fertilizer inputs (0 or 50 kg ha−1), sheep stocking densities (12 or 9 ewes ha−1) and average sward heights in summer were constrained to 3·5 or 5·5 cm by conserving surplus grass for silage in subplots. Five treatments, replicated in three randomized blocks, combined the two stocking densities and two sward heights without nitrogen fertilizer inputs, with the fifth combining the higher stocking density, shortest sward height and the nitrogen fertilizer input. Beetles were sampled with twelve pitfall traps in each of the fifteen plots from June to September in 1993 and 1995.In years 1 (1993) and 3 (1995) of the experiment, more Coleoptera species occurred in the tall sward (an average of nine species in addition to the forty-one species present in the sward with the conventional sward height). Continuously grazed as opposed to ensiled subplots supported more beetle species but fewer individuals. Species composition of ground (Carabidae) and rove (Staphylinidae) beetles varied between treatments more than the arithmetic differences in species number.The experimental results supported the hypothesis but the benefits of taller swards to species diversity were small in the sown pastures of the study compared with indigenous upland grasslands (c. 33% fewer species). Inheritance effects of drainage, fertilizer and lime inputs, and the different species and management of cultivated pastures, may constrain the conservation benefits of altered pasture management compared with indigenous grasslands.

Notes: When describing the methods of analysis of neutral-detergent fibre (NDF) it is valuable to know if different modifications of the standard method of analysis give the same absolute results or if the analysing method has to be specified. In this study two modifications of the standard method were compared, a 16-h oven technique and a filter-bag technique. The comparisons were conducted using thirty-two timothy (Phleum pratense L.) and thirty-two red clover (Trifolium pratense L.) samples. The study showed that both methods ranked the forage samples in the same relative order and had good accuracy. However, the NDF concentrations for the filter-bag system were on average 7·8 g kg−1 DM higher for the red clover samples and 39·7 g kg−1 DM higher for the timothy samples. The difference in concentration of NDF for the red clover samples was smaller than the field variation and the daily change in NDF concentration, but in timothy the difference was four to five times larger than the field variation and the mean daily changes in NDF concentration. The study shows that it is important to specify the method of analysis for NDF when analysing timothy samples but not red clover samples, and that for this dataset it was possible to use a correction constant to recalculate the results from one method to the other.

Notes: The sustainability of white clover in grass/clover swards of an upland sheep system, which included silage making, was studied over 5 years for four nitrogen fertilizer rates [0 (N0), 50 (N50), 100 (N100) and 150 (N150) kg N ha−1]. A common stocking rate of 6 ewes ha−1 was used at all rates of N fertilizer with additional stocking rates at the N0 fertilizer rate of 4 ewes ha−1 and at the N150 fertilizer rate of 10 ewes ha−1. Grazed sward height was controlled, for ewes with their lambs, from spring until weaning in late summer by adjusting the proportions of the total area to be grazed in response to changes in herbage growth; surplus pasture areas were harvested for silage. Thereafter sward height was controlled on separate areas for ewes and weaned lambs. Areas of pasture continuously grazed in one year were used to make silage in the next year. For treatments N0 and N150, white clover stolon densities (s.e.m.) were 7670 (205·4) and 2296 (99·8) cm m−2, growing point densities were 4459 (148·9) and 1584 (76·0) m−2 and growing point densities per unit length of stolon were 0·71 (0·015) and 0·67 (0·026) cm−1 respectively, while grass tiller densities were 13 765 (209·1) and 18 825 (269·9) m−2 for treatments N0 and N150 respectively. White clover stolon density increased over the first year from 780 (91·7) cm m−2 and was maintained thereafter until year 5, reaching 8234 (814·3) and 2787 (570·8) cm m−2 for treatments N0 and N150 respectively. Growing point density of white clover increased on treatment N0 from 705 (123·1) m−2 to 2734 (260·7) m−2 in year 5 and it returned to the initial level on treatment N150 having peaked in the intermediate years. Stolon density of white clover was maintained when the management involved the annual interchange of continuously grazed and ensiled areas. The non-grazing period during ensiling reduced grass tiller density during the late spring and summer, when white clover has the most competitive advantage in relation to grass. The increase in stolon length of white clover in this period appears to compensate for the loss of stolon during periods when the sward is grazed and over winter when white clover is at a competitive disadvantage in relation to grass. The implications for the management of sheep systems and the sustainability of white clover are discussed.

Notes: We sought to examine the distribution of carbon (C) decomposition within the framework of the soil pore system. Soils were sampled from a transect having a natural gradient in pore-size distribution. After the addition of labelled wheat straw (13C) the repacked soil columns were incubated (25°C) at soil water matric potentials of either −75 kPa or −5 kPa and for either 4 or 90 days. Pore-size distribution was determined for each soil column after incubation and soils were then analysed for soluble C, label-derived residual C, label-derived and native biomass C, nematode abundance, and ergosterol concentration as an indicator of fungal biomass. Overall, the data suggested that pore-size distribution and its interaction with soil water give rise to a highly stratified biogeography of organisms through the pore system. This results in different rates of decomposition in pores of different size. Added plant material seemed to decompose most rapidly in soils with a relatively large volume of pores with neck diameters c. 15–60 µm and most slowly in soils with large volumes of pores with neck diameters 〈 4 µm. Regression analysis suggested that at matric potentials of both −75 kPa and −5 kPa the fastest decomposition of organic substrate occurred close to the gas–water interface. This analysis also implied that slower rates of decomposition occur in the pore class 60–300 µm. Correlations between the mass of soil biota and the pore volume of each pore class point to the importance of fungi and possibly nematodes in the rapid decomposition of C in the pores c. 15–60 µm during the early stages of decomposition.

Notes: Pesticides leaching through a soil profile will be exposed to changing environmental sorption and desorption conditions as different horizons with distinct physical and chemical properties are encountered. Soil cores were taken from a clay soil profile and samples taken from 0.0 to 0.3 m (surface), 1.0–1.3 m (mid) and 2.7–3.0 m (deep) and treated with the chloroacetanilide herbicide, acetochlor. Freundlich isotherms revealed that sorption and desorption behaviour varied with each depth sampled. As soil depth increased, the extent and strength of sorption decreased, indicating that the potential for leaching was increased in the subsoils compared with the surface soil. Hysteresis was evident at each of the three depths sampled, although no significant correlations between soil properties and the hysteresis coefficients were evident.Desorption studies using soil fractions with diameters of 〉 2000, 250–2000, 53–250, 20–53, 2–20, 0–2 and 0–1 µm separated from each of the three soil depths showed that differential desorption kinetics occurred and that the retention of acetochlor significantly correlated (R2 = 0.998) with organic matter content. A greater understanding of the influence of soil components on the overall sorption and desorption potential of surface and subsurface soils is required to allow accurate prediction of acetochlor retention in the soil. In addition, it is likely that the proportion of each size fraction in a soil horizon would influence acetochlor bioavailability and movement to groundwater.

Notes: The prediction of the mobility of arsenic (As) is crucial for predicting risks in soils contaminated with As. The objective of this study is to predict the distribution of As between solid and solution in soils based on soil properties and the fraction of As in soil that is reversibly adsorbed. We studied adsorption of As(V) in suspensions at radiotrace concentrations for 30 uncontaminated soils (pH 4.4–6.6). The solid–liquid distribution coefficient of As (Kd) varied from 14 to 4430 l kg−1. The logarithm of the concentration of oxalate-extractable Fe explained 63% of the variation in log Kd; by introducing the logarithm of the concentration of oxalate-extractable P in the regression model, 85% of the variation in log Kd is explained. Double labelling experiments with 73As(V) and 32P(V) showed that the As to P adsorption selectivity coefficient decreased from 3.1 to 0.2 with increasing degree of P saturation of the amorphous oxides. The addition of As(V) (0–6 mmol kg−1) reduced the Kd of 73As up to 17-fold, whereas corresponding additions of P(V) had smaller effects. These studies suggest that As(V) is adsorbed to amorphous oxides in soils and that sites of adsorption vary in their selectivity in respect of As and P. The concentration of isotopically exchangeable As in 27 contaminated soils (total As 13–1080 mg kg−1) was between 1.2 and 19% (mean 8.2%) of its total concentration, illustrating that a major fraction of As is fixed. We propose a two-site model of competitive As(V)–P(V) sorption in which amorphous Fe and Al oxides represent the site capacity and the isotopically exchangeable As represents the adsorbed phase. This model is fitted to 73As adsorption data of uncontaminated soils and explains 69% of the variation of log Kd in these soils. The log Kd in contaminated soils predicted using this two-site model correlated well with the observed log Kd (r = 0.75). We conclude that solubility of As is related to the available binding sites on amorphous oxides and to the fraction of As that is fixed.

Notes: Hydroxylamine hydrochloride (NH2OH-HCl) and hydrogen peroxide (H2O2) have been used in the past for selective dissolution of manganese oxide minerals. The methods reported, however, give poor recoveries. We tried to improve the methods in this respect. By stoichiometry, incomplete dissolution of Mn oxides is due to the lack of NH2OH-HCl added or to the lack of acid added in the case of H2O2 treatment. By increasing the amount of solution for a given amount of solid in the case of NH2OH-HCl and by increasing the acid concentration in the case of H2O2 treatment, we obtained rapid and complete dissolution of synthetic Mn oxides. The dissolution of natural samples, however, was slower than that of synthetic ones. Based on the results obtained, the improved methods are: (i) 0.1 m NH2OH-HCl, non-acidified, 2 hours' stirring, and 1 g solid in 2 litres solution; (ii) 30% H2O2 in 0.5 m nitric acid, 0.5 hours' stirring, and 1 g solid in 1 litre solution. The improved methods achieved almost complete release of manganese from samples without decreasing the selectivity of dissolution.

Notes: Weathering of soil minerals is a key determinant of ground and surface water quality and is also important in pedogenic and rhizosphere processes. The relative importance of biotic and abiotic studies in mineral weathering, however, is poorly understood. We investigated the impact of Picea abies seedlings, an ectomycorrhizal fungus and humic acid on the solubilization of aluminium (Al), iron (Fe) and silicon (Si) in an E horizon forest soil over 10 months. Elemental budgets were constructed based upon losses in drainage water, accumulation in plants and changes in the pools of exchangeable ions. Plants and mycorrhizas or both had a significant effect on the total amounts of Al, Fe and Si mobilized from the soil. Significantly larger amounts of Al and Fe were recovered in plants than those lost in drainage water, whereas the opposite trend was true for Si. The continual addition of dissolved organic matter to the soil in the form of humic acid had an effect only on mobilization of Fe, which increased due to larger plant uptake and an increase in the exchangeable pool. The mobilization of Fe and Si were positively correlated with hyphal length, soil respiration and concentrations of oxalate in the soil solution, and mobilization of Al was strongly correlated with plant weight. Scanning electron microscopy revealed that most fungal hyphae were associated with mineral surfaces with little occupation of cracks and micropores within mineral grains. Evidently ectomycorrhizas have important impacts on mineral dissolution and the chemistry of forest soils.

Notes: The sequestration of dung carbon in soil depends on the location and rate at which it is immobilized in soil aggregates. Here C4 dung (δ13C = −16.1‰) or C3 dung (δ13C = −26.8‰) were applied to a temperate permanent pasture C3 soil (δ13C = −27.9‰). Triplicate samples were taken from C3 and C4 dung remaining at the surface, and in the 0–1 and 1–5 cm soil layers in the unamended control and under the C3 and C4 dung patches after 7, 14, 29, 42 and 70 days after the application of the dung. Macroaggregates (≥ 4 mm) at the lower depth (1–5 cm) were mechanically fractionated into surface and core fractions by a combination of shock freezing followed by wet sieving.Neither overall nor differential carbon isotope fractionation occurred in the dung remaining at the surface. The incorporation of C4 dung significantly increased the δ13C content of the 0–1 cm layer of the C3 soil. Dung C sequestration did not exceed 10% for the 0–1 cm layer and was only 20% for the whole soil (0–30 cm) during the 7-day experiment. Only 32–66% of the C from dung in the 1–5 cm layer was sequestered in the aggregates; the major proportion was initially preferentially attached to their surfaces, but incorporated into aggregates within the following 14 days. The majority of dung, however, soon resided between the aggregates, pointing to the important role of the inter-aggregate fraction in short-term C dynamics of dung in this pasture soil.

Notes: The herbicide glyphosate and inorganic phosphate are strongly adsorbed by inorganic soil components, especially aluminium and iron oxides, where they seem to compete for the same adsorption sites. Consequently, heavy phosphate application may exhaust soil's capacity to bind glyphosate, which may lead to pollution of drain- and groundwater. Adsorption of phosphate and glyphosate to five contrasting Danish surface soils was investigated by batch adsorption experiments. The different soils adsorbed different amounts of glyphosate and phosphate, and there was some competition between glyphosate and phosphate for adsorption sites, but the adsorption of glyphosate and phosphate seemed to be both competitive and additive. The competition was, however, less pronounced than found for goethite and gibbsite in an earlier study. The soil's pH seemed to be the only important factor in determining the amount of glyphosate and phosphate that could be adsorbed by the soils; consequently, glyphosate and phosphate adsorption by the soils was well predicted by pH, though predictions were somewhat improved by incorporation of oxalate-extractable iron. Other soil factors such as organic carbon, the clay content and the mineralogy of the clay fraction had no effect on glyphosate and phosphate adsorption. The effect of pH on the adsorption of glyphosate and phosphate in one of the soils was further investigated by batch experiments with pH adjusted to 6, 7 and 8. These experiments showed that pH strongly influenced the adsorption of glyphosate. A decrease in pH resulted in increasing glyphosate adsorption, while pH had only a small effect on phosphate adsorption.

Notes: Helicopter electromagnetic (HEM) systems are commonly used for conductivity mapping and the data are often interpreted using an isotropic horizontally layered earth model. However, in regions with distinct dipping stratification, it is useful to extend the model to a layered earth with general anisotropy by assigning each layer a symmetrical 3 × 3 resistivity tensor.The electromagnetic (EM) field is represented by two scalar potentials, which describe the poloidal and toroidal parts of the magnetic field. Via a 2D Fourier transform, we obtain two coupled ordinary differential equations in the vertical coordinate. To stabilize the numerical calculation, the wavenumber domain is divided into two parts associated with small and large wavenumbers. The EM field for small wavenumbers is continued from layer to layer with the continuity conditions. For large wavenumbers, the EM field behaves like a DC field and therefore cannot be sensed by airborne EM systems. Thus, the contribution from the large wavenumbers is simply ignored.The magnetic fields are calculated for the vertical coaxial (VCX), horizontal coplanar (HCP) and vertical coplanar (VCP) coil configurations for a helicopter EM system. The apparent resistivities defined from the VCX, VCP and HCP coil responses, when plotted in polar coordinates, clearly identify the principal anisotropic axes of an anisotropic earth. The field example from the Edwards Aquifer recharge area in Texas confirms that the polar plots of the apparent resistivities identify the principal anisotropic axes that coincide well with the direction of the underground structures.

Notes: The diffusion of electromagnetic fields is dependent not only on conductivity, but also on magnetic permeability, dielectric permittivity and polarizability, i.e. dispersive conductivity. The long-offset transient electromagnetic (LOTEM) method is mainly used to determine the spatial distribution of conductivity in the subsurface. However, earlier work on loop-loop TEM suggests that transient EM methods can also be affected by induced polarization (IP).Numerous 1D forward calculations were carried out to study the IP effect on LOTEM data, using the Cole-Cole relaxation model to simulate the polarizability of the ground. Besides the polarizability of each layer, the IP effect depends on the LOTEM field set-up and the spatial distribution of conductivity in the ground. In particular, near-surface layers with high chargeabilities can significantly distort the late time transients of the electric field components in the vicinity of the transmitter. The influence of polarizable layers on the magnetic field components can be neglected under normal circumstances.In 1997 and 1999, LOTEM measurements were carried out at Mt. Vesuvius in Italy to explore the geological structure of the volcano. Sensitivity studies on the effect of polarizable layers suggest that high chargeabilities in connection with conductive layers at greater depths would result in a detectable distortion of the electric field transients. Although the simultaneous IP measurements revealed high chargeabilities in a near-surface layer, no evidence of IP effects could be found in the measured LOTEM data. We conclude that the observed chargeabilities are local and that 3D effects are probably present in the data.Another aspect is the measurement of the system response, which is usually measured by placing a receiver very close to the transmitter. Therefore, large distortions can be expected if near-surface polarizable layers exist. This was verified in practice by field measurements in an area with high chargeabilities in Longerich, Cologne.

Notes: A database on the productivity of red clover (Trifolium pratense), white clover (Trifolium repens), lucerne (Medicago sativa), lotus (Lotus corniculatus) and galega (Galega orientalis) was compiled. It contains 1852 observations for 330 trials at fifty-three sites in eight north European countries for the period from 1977 to 1997. The database includes information on climatic and site characteristics, as well as agronomic data, collated into four smaller data sets. This has permitted four key agronomic issues to be examined, namely: (i) how yield for a given variety varies under different environmental conditions; (ii) how the relative performance of different species varies between sites; (iii) how persistence varies between species and sites; and (iv) what the nature of the relationship is between varieties, yield and sites within a species? Cluster analysis revealed that geographical location had a fairly strong influence on yield. Across sites for an individual variety, the cumulative day-degrees during the regrowth period had the highest correlation with total yield. In terms of the relative performance of different forage legume species across sites, red clover and lucerne were estimated to yield about 2·5 t DM ha−1 more than white clover and there was a significant impact of cumulative day-degrees during regrowth and the age of ley on the total yield. It was found that red clover had the lowest persistence index and lucerne the highest. As regards the interaction between yield, varieties and sites, the length of growth period and the age of the ley explained two-thirds of the variation in total yield in red clover varieties of contrasting maturity types.

Notes: Fertilizer-nitrogen (N) management is a decisive factor in grass-based, intensive dairy farming, as it strongly influences economic and environmental performance but little attention has been paid to providing guidance on N-fertilizer management at an operational level to meet these criteria of performance. Essential criteria in operational N-fertilizer management were identified as target dry matter (DM) yield of herbage, growth period per cut, herbage N concentration, N use efficiency (NUE), amounts of unrecovered N and marginal N response. Statistical relationships between fertilizer-N application rates per cut and these criteria were derived from field experiments. These relationships were then used to explore the effects of the criteria on optimum fertilizer-N applications.Optimum fertilizer-N rates depended strongly on target levels for NUE, amounts of unrecovered N, growth period and DM yield of herbage. Calculations showed that target DM yield of herbage and growth period per cut are essential in estimating the effect of applied N on marginal N response, NUE and amounts of unrecovered N. The derived relationships can be used to explore the effects of changes in target levels of the criteria on optimum fertilizer-N applications. The study showed that operational fertilizer-N management set constraints to the decisions made at strategic and tactical management levels and vice versa.

Notes: The combined benefits of a high crude protein concentration, and possible protein protection and growth-promoting properties, make forage legumes potentially attractive as a natural means of increasing liveweight gain and time to slaughter of lambs in lamb finishing systems. An experiment was conducted to compare the production performance and meat quality of grazing lambs finished on red clover (Trifolium pratense), lucerne (Medicago sativa) or perennial ryegrass (Lolium perenne) swards. Replicate (n = 2) swards of red clover, lucerne and perennial ryegrass were rotationally grazed by ten ram lambs and ten ewe lambs from weaning until selection for slaughter at UK fat class 3L. Lambs grazing the red clover sward had a significantly higher liveweight gain and required significantly fewer days to slaughter than lambs grazing the lucerne sward (305 g d−1 vs. 243 g d−1; 38 d vs. 50 d), which in turn had a higher liveweight gain and required fewer days to slaughter than lambs grazing the perennial ryegrass sward (184 g d−1; 66 d). Lambs grazing the red clover and lucerne swards had significantly higher herbage intakes than those grazing the perennial ryegrass sward (2·06, 1·72 and 1·16 kg DM d−1 respectively), but in vivo digestibility of herbage was similar. Lambs grazing the red clover and lucerne swards also had significantly higher serum urea concentrations than those grazing ryegrass (12·5, 11·1 and 6·2 mmol L−1 respectively). Killing-out percentage was significantly higher for lambs grazing the red clover sward than for lambs grazing the perennial ryegrass sward (48% vs. 46%). There were no significant effects of finishing system on meat flavour, but meat from lambs finished on the lucerne sward was oxidatively less stable than that from lambs finished on the perennial ryegrass sward. Grazing the forage legume swards significantly increased the proportion of linoleic and linolenic acid in muscle tissue, and therefore the proportion of unsaturated to saturated fatty acids (0·19, 0·16 and 0·12 for the red clover, lucerne and perennial ryegrass swards respectively). However, the n−6/n−3 ratio was significantly lower for the muscle of lambs grazing the perennial ryegrass sward compared with those grazing the forage legume swards (1·13, 1·08 and 0·98 for the red clover, lucerne and perennial ryegrass swards respectively). The results indicate that by grazing lambs on forage legume swards it is possible to increase individual lamb performance without compromising meat quality.

Notes: The dry matter (DM) yield and degradability of 6-week-old harvests of tropical forages were measured over a season. The forages were nitrogen-fertilized Guinea grass (Panicum maximum, NFG), unfertilized Guinea grass (UFG), Verano stylo (Stylosanthes hamata,VS), a Guinea grass–Verano stylo mixture (GSM) and Guinea grass in the grass–Verano stylo mixture (GGSM). Six-week-old forages were made possible through a cutting regime, which produced four harvests in the growing season. The DM yields of the forages differed significantly (P 〈 0·001) and showed a significant reduction (P 〈 0·01) across the season. Crude protein and neutral-detergent fibre concentrations were significantly (P 〈 0·01) different between the forages but there was no difference between harvests. The DM degradability of the forages at all harvests were significantly (P 〈 0·001) different with differences in the soluble fraction (a), degradable fraction (b), potential degradability (PD) and effective degradability (ED), but rate of degradability (c) did not show any significant difference between the forages. Significant (P 〈 0·01) differences were found between harvests for b and PD, and for the interaction between forage and harvest for b, PD and ED but were not found for the a and c fractions. Both the PD and ED values of all the forages fell with advancing harvests. Although the 6-week-old harvests of forage were found not to influence the characteristic reduction in yield of tropical grasses over time, it is concluded that such a management system could be used to obtain forage of relatively high nutritive value during the growing season.