ALBERT

Notizen: Abstract. The impact of cattle trampling on the porosity of a representative soil (Typic Natraquoll) of the flooding Pampa of Argentina was studied from 1984 to 1987. Water content, total porosity (TP), macroporosity (〉 30 μm) and mean weight diameter of water-stable aggregates (MWD) were determined in undisturbed topsoil samples taken from adjacent continuously grazed (1.0 animal unit/ha/yr) and ungrazed (since 1976) areas. It was expected that trampling would decrease macroporosity when the soil was ponded, and that the damaged macropores would regenerate during the subsequent soil drying. This was only partly verified. The soil varied in TP from 58 to 64% in the ungrazed area, and from 53 to 78% in the grazed area. This variation resulted mainly from shrink-swell processes. Trampling decreased soil macroporosity (mainly 〉60 μm) from 8 to 5% and decreased MWD from 5.35 to 4.58 mm under dry soil conditions. The damaged soil pores regenerated and aggregate stability recovered during the subsequent period of surface water ponding, when soil swelling increased macropores in the grazed area but not in the ungrazed area. There was no evidence of poaching damage in this soil.

Notizen: Book Reviewed in this article:Soils and the Environment By Alan Wild.Nitrate. Processes, Patterns and Management Edited by T.P. Hurt, A.L. Heathwaite and S.T. Trudgill.Urban Soil and Landscape Design By P.J. Craul.Bullock, P. & Gregory, P. J. 1991. Soils in the urban environment.

Notizen: Abstract. Recent experiments on soils overlying sand, chalk and limestone aquifers have shown that nitrate leaching losses can be decreased by modifying crop husbandry. Green cover during winter, if established early enough, can reduce nitrate loss. Cultivations can be timed to minimize leaching, and the advantages of irrigation (increased nitrogen offtake and smaller post-harvest soil mineral nitrogen residues) outweigh the potential disadvantage of increased leaching risk during the growing season. It is important not to over-fertilize crops. Using these techniques within farm rotations has decreased nitrate losses in small plot experiments. The next step is to measure the effects on commercial farms where the scale of operation might preclude the high level of husbandry that is required for successful nitrogen management.

Notizen: Book Reviewed in this article:Lysimeter Studies of the Fate of Pesticides in the Soil Edited by F. Führ and R. J. Hance.

Notizen: Abstract. The effects of increasing periods of mechanical cultivation on soil properties under maize and cassava are compared with those under savanna in south-western Nigeria. Bulk density is significantly greater under cultivation and total porosity, pH, organic matter and extractable nutrients are all significantly less than under savanna. However, the amounts of nitrate-nitrogen and extractable nutrients do not show clear decreases with increasing mechanical cultivation. As the periods of mechanization increase, changes in most soil properties indicate increasing soil degradation. The implications of these results for agricultural policies in Nigeria arc discussed.

Notizen: Abstract. Leaching of nitrate from a sandy loam cropped with spring barley, winter wheat and grass was compared in a 4-year lysimeter study. Crops were grown continuously or in a sequence including sugarbeet. Lysimeters were unfertilized or supplied with equivalent amounts of inorganic nitrogen in calcium ammonium nitrate (CAN) or animal slurry according to recommended rates (1N) or 50% above recommended rates (1.5N).Compared with unfertilized crops, leaching of nitrate increased only slightly when 1N (CAN) was added. Successive annual additions of 1.5N (CAN) or 1N and 1.5N (animal slurry) caused the cumulative loss of nitrate to increase significantly. More nitrate was leached after application of slurry because organic nitrogen in the slurry-was mineralized.With 1N (CAN) the leaching losses of nitrate were in the following order: continuous spring barley undersown with Italian ryegrass 〈 continuous ley of perennial ryegrass 〈 spring barley in rotation and undersown with grass 〈 perennial ryegrass grown in rotation = winter wheat grown in rotation 〈 sugarbeet in rotation 〈 continuous winter wheat 〈 continuous barley 〈 bare fallow.At recommended levels of CAN (1N), cumulative nitrate losses over the four years were similar for the crops when grown in rotation or continuously. When crops received 1.5N (CAN) or animal slurry, nitrate losses from the crops grown continuously exceeded those from crops in rotation. Including a catch crop in the continuous cropping system eliminated the differences in nitrate leaching between the two cropping systems.

Notizen: Abstract. Changes in amounts of macro-(N, P, K) and micro-nutrients (Fe, Mn, Zn and Cu) were determined in two calcareous soils amended over an eight-month period with pig slurry applications ranging from 0 to 500 m3/ha, and planted in containers with green pepper (Capsicum annuum). Total N and exchangeable K increased after slurry applications of 300 m3/ha or more, and available P increased after the smallest application rate (100m3/ha). Maximum crop nutrient uptakes of 41, 40 and 91% for N, P and K occurred with the smallest dose of slurry. Large losses of N, ranging from 27 to 74% (mean 55%) of N added to soil, occurred with all slurry treatments. From 41 to 71% (mean 55%) of the total P added in pig slurry was fixed in non-assimilable forms. Most of the K from the pig slurry was available to the plants. Most of the micro-nutrients (Fe, Mn, Zn and Cu) from the slurry were immobilized in the soil, probably because of the high pH and the small amounts of organic matter in both the slurries and soils tested.

Notizen: Abstract. Oxidation rates of pyrite in colliery spoil were measured under both field and laboratory conditions. Meld oxidation rates varied through the year, depending primarily upon temperature. Rates of acid release of 7–15 μmoles H+/day were measured in field lysimeters in the period May to November. Little oxidation of the pyrite occurred between November and May; the rates in the summer months were approximately 5–10 times those during die winter. The rate of oxidation in the summer was limited by the solubility of amorphous iron oxides. Slow oxidation during the winter is probably related to the inactivity of Thiobacillus ferrooxidans at low temperatures. The rates of acid production in the laboratory in the temperature range 0–18°C were similar to those in the field. Materials inhibiting pyrite oxidation should be added when oxidation rates are slow, so that they are not overwhelmed by large amounts of acid.

Notizen: Abstract. . A soil crust, produced by applying 44 mm of distilled water at an intensity of 290 mm/h using a rainfall simulator, was sufficiently rigid to significantly decrease emergence of barley from 76 to 40% and of oil seed rape from 82 to 61%. If the crust was kept wet by regular application of water as a fine mist, its strength was significantly decreased, but emergence remained poor because of prolonged soil wetness. After mist-spraying the crusted surface just before emergence, per cent emergence was greater than uncrusted controls.Application to the soil of a static pressure after sowing but without crusting either had no effect or increased emergence, probably because of improved seed-soil contact. However, crusting of the compacted soil decreased emergence severely. If the crust was allowed to dry it became very strong (〉 300 kPa). Mist-spraying at the time of emergence only also improved seed emergence almost to that in the uncrusted controls. Repeated mist spraying after crusting decreased the strength of the crust, but the resulting waterlogging decreased emergence to less than half those of the controls and of the treatments sprayed just before emergence only. Compared with other management techniques available for amelioration of crusted seedbeds, carefully timed fine spray watering seems to offer the best opportunity for ensuring rapid seed emergence comparable to that in uncrusted soils.

Notizen: Abstract. A land evaluation at farm level was made for a toposequence of three New York soils, using the FAO framework and the LEACHN simulation model. The land utilization type (LUT) was continuous corn, using three varieties with different growing periods. Ten experts identified the same land qualities but three different types of land characteristics, as derived from soil survey data, field observations and simulation modelling. Differences could be explained by the backgrounds of the experts. A land evaluation procedure according to framework criteria using decision trees rather than matching tables was more accessible and transparent. Simulation of the soil-water regime provided quantitative data for all land qualities considered, and this procedure was preferred to qualitative estimates based on poorly defined procedures. When some land qualities cannot be characterized by simulation, however, a mix of qualitative and quantitative decision tree branches may be considered. The standard scheme of land evaluation, which is scale independent, provides irrelevant results at farm level because farmers’ questions are different from those of regional planners who are well served by the traditional land evaluation procedure. For the farmer, development of decision support systems should be focused on optimal management decisions.

Notizen: Abstract. Runoff and soil loss were measured using simulated rainfall at nine shrubland sites on gypsiferous soils in the Ebro Valley. The sites represented diverse physiographical situations, including three soil types, three slopes and different percentages of rock outcrop and vegetation cover. Soil type, slope and vegetation cover significantly affected runoff and soil losses. An average of 40% of the simulated rainfall (48 mm/h) appeared as runoff and amounts were positively correlated with soil losses. The greatest runoff and soil losses were from plots with the steepest slopes. Rock outcrops decreased soil losses.

Notizen: Abstract. Organic manures contain valuable quantities of nitrogen, phosphate and potash, but many farmers regard them as ‘waste materials’ rather than as sources of plant nutrients. Utilization of the plant-available nitrogen content is poor at present because of manure management practices which lead to leaching and atmospheric losses. Experiments studying the effect of timing suggest that, in order to decrease nitrate leaching, applications of manures which contain much available nitrogen should not be made during the period September to December on freely draining grassland and arable soils. Spring top dressings of dilute pig or cattle slurries and poultry manures to growing cereal crops are generally more efficient than autumn applications, particularly on freely draining soils. Legislation requiring manures to be applied in an environmentally acceptable manner and the economic need for farmers to realize the nutrient value of organic manures are likely to change the farming industry's perception of manures as ‘waste materials’.

Notizen: Abstract. Finely ground limestone waste from lead mining is discarded as useless but could be a valuable alternative to agricultural limestone. A glasshouse pot experiment established that it is an effective liming material. Two kinds were used: one from north Wales (HMT) represented metal-rich waste produced by the older water-gravity separation of ores; the other (NLB) was a modern flotation tailings. A commercial lime (CLS) was used for comparison. The materials were applied to an acid soil in quantities sufficient to raise the pH to 7 (single liming) and at much greater rates equivalent to annual limings for 369 years. All treatments were replicated five times and the soil/lime mixtures were analysed for EDTA-extractable lead, zinc and cadmium. Radish was grown as the test plant and hypocotyl and leaf tissue were analysed for the same metals. The larger additions of HMT and NLB caused chlorosis and decreased yields. The cadmium and lead concentrations of leaves and hypocotyls suggested that the HMT material could be safely applied to soil annually for 79 years and NLB for 277 years. It is concluded that NLB can be used as agricultural limestone.

Notizen: Abstract. Pollution by inorganic and organic substances is increasingly disrupting the natural functions of soils. Some soils seem capable of receiving and holding chemical compounds, at the same time retaining their ecological flexibility, but others are readily damaged and should be regarded as vulnerable to particular pollution scenarios.At the request of the Chemical Time Bombs (CTB) Project, the International Soil Reference and Information Centre (ISRIC) organized an international workshop to assess the feasibility of increasing awareness of ‘soil vulnerability’ by a mapping exercise for Europe (SOVEUR), at a scale of 1:5 M, with reference to selected organic and inorganic contaminants. The workshop participants outlined procedures for a GIS-based approach to determining areas where vulnerable soils occur, and formulated proposals for the implementation phase of the SOVEUR programme. Funding is now sought for continuation of the work outlined in this paper.

Notizen: Book Reviewed in this article:The Evaluation of Land Resources By D.A. Davidson.

Notizen: Abstract. Preferential flow paths (PFP) are important in water and solute movement through soils, especially in regions where vertical water movements predominate, such as the flooding Pampa (Argentina). The impact of grazing on PFP and its interactions with other properties were studied in three soils with natric horizons in the flooding Pampa using an iodide colouring technique. In the soil with a mollic horizon (Typic Natraquoll), % PFP was decreased by trampling but was later restored by shrink-swell. In the Typic Natraqualf, the most alkaline of the studied soils, % PFP was very small under both grazed and ungrazed conditions. In a coarser textured soil (Mollic Natraqualf) trampling did not affect % PFP. The % PFP of the Ah horizons increased with increasing organic carbon and sand contents and decreased as clay content, pH and sodium adsorption ratio (SAR) increased. The Bt horizons had small % PFPs and were not affected by cattle trampling.

Notizen: Abstract. A quantitative knowledge of nitrogen cycle processes is required to design strategies for decreasing leakage of N from agriculture to the wider environment. However, it is remarkably difficult to make reliable measurements of many of the key processes under realistic field conditions. In impermeable soils hydrologically separated plots provide an invaluable method of measuring leaching and runoff. Estimates of nitrate leaching using porous ceramic cups agree well with lysimeter measurements on sandy soil but are suspect on more structured soils. Estimates of N2O flux from soil are subject to great spatial heterogeneity; developing long path-length measuring techniques may overcome this problem. 15N labelling is valuable for assessing fertilizer N loss, forms of N left in soil and the fate of N from crop residues. The combination of experimental and modelling approaches can provide insights that are otherwise unattainable, including a basis for more precise advice on N fertilization.Mineralization of soil organic matter and crop or animal residues provides much of the nitrate leached during winter under the climatic conditions of north-west Europe, because mineralization is poorly synchronized with crop N uptake. Maintenance of crop cover during winter can greatly decrease leaching but the long-term effects on the N cycle of winter cover crops or incorporating cereal straw are not yet clear.

Notizen: Abstract. Rural agricultural areas in southern Ontario, Canada, with potential for aggregate extraction have become a focus of conflict over proposed land use change. Geophysical and soil physical field measurements were used to map soil variation for quantitative land evaluation at the farm level. Apparent electrical conductivity of terrain was shown to be strongly correlated with depth to the groundwater table on two separate test sites. A digital terrain model was used to create thematic maps of the predicted pre-growing season soil water regime by contouring irregularly spaced electromagnetic survey and soil inspection points. Overlay analysis with a geographical information system (GIS) was used to produce an agricultural soil capability map for crop production. Adoption of a larger map scale provided significant refinement in detail over the published Canada Land Inventory soil capability ratings for agriculture, but both showed that Class 2 soils are dominant. The approach can improve the reproducibility of land capability assessments.

Notizen: Abstract. The contribution of agriculture to the nitrogen pollution of surface and ground waters of calcareous lake soils in the Kopais area (190 km2) of Greece was studied over three cropping seasons. Sample fields were chosen from seven representative soil units under different crop rotations. The distribution of mineral N (NO3-N + NH4-N) throughout the soil profile and the concentration of NO3-N in the ground water and drainage water were measured and allocated to 6-month winter or spring periods. For all fields N was leached to the deeper soil layers and to the saturated zones by both excess winter rainfall and spring irrigation of different crops The amount of nitrogen leached depended on the amount of nitrogen fertilizer applied; the depth of leaching varied with the physical properties of the soils. Losses in individual fields accounted for the equivalent of 17.6–80.8% of the nitrogen applied to maize and 70.5–94.1% of that applied to wheat. For the whole region estimated minimum N losses ranged from 175, 912 to 783, 564 kg for the 6-month period. Nitrate concentrations in the ground and surface waters were often more than the EC target level of 25 mg/1.

Notizen: Abstract. The infiltration and runoff responses of degraded and non-degraded semi-arid land surfaces were investigated by rainfall simulation in the Lowveld of Swaziland. The hydrological response of the soil was controlled by changes in the properties of the soil surface, the nature of which was dependent upon rainfall intensity and antecedent moisture, as well as upon soil type and condition. Rather than there being one final steady-state infiltration rate for a given soil type and condition (i.e. a constant of soil response), the final rates achieved were variable for each soil type and condition, and depended upon rainfall intensity and antecedent moisture. The implications of this for soil use and management in terms of infiltration measurement and runoff assessment are considered.

Notizen: Abstract. Soil workability and trafficability are frequently estimated from meteorological data. This paper discusses the importance of soil workability for crop production, and reviews the limitations of various models, especially their applicability for predicting the effects of climate change. Some models calculate the number of spring or autumn work-days by combining meteorological and soil-related factors. Most of these determine, either empirically or deterministically, daily soil moisture budgets from which workability is inferred. A shortcoming of this approach is that it requires critical soil moisture contents or potentials. Also there are problems with the persistence of water in the profile and with the allocation of rainfall events to specific days. Determining work-days over seasonal periods avoids these limitations, but this approach is unsuitable for short-term planning purposes. The value of workability models is difficult to gauge as they often apply to specific soil and climatic conditions. This limitation will increase under a changing climate. For example, soil properties, previously considered as intrinsic, may alter in a manner that invalidates some models. More work on the soil processes controlling workability is needed, and on how these will be affected by a changing climate.

Notizen: Abstract. The land of the Nigerian Institute for Oil Palm Research (NIFOR) main station in southern Nigeria was evaluated for suitability for oil palm cultivation by the FAO system using data from 12 pedons representing four soil series. The results indicate that although the climatic factors are near optimum and more than half of the pedons were potentially moderately (S2) or highly (S1) suitable, the current suitability is marginal (S3). The major limitations were soil fertility (K mole fraction, CEC) and particle size. In this and similar environments good soil management is required before substantial improvements in oil palm production can be achieved.

Notizen: Abstract. Field trials measured the benefits of using soil in the reclamation of colliery spoil. Increasing the thickness of the soil cover increased grass yield, particularly on a site with potentially acidic spoil materials. Mixing soil with the underlying spoil increased yield slightly compared to using the same amount of soil as a cover. From these and earlier results, we conclude that: the use of soil as a cover is essential on sites with acidic, or potentially acidic, spoil; to be effective in the short-term, the thickness of soil can be as little as 15 cm; the use of soil on sites with non-acidic spoil is beneficial in terms of physical conditions, such as improved water-holding capacity and better root penetration; the benefits of incorporating the soil on such sites are probably insufficient to justify the additional effort involved.

Notizen: Abstract. The concern over leakage of nitrate into waters and loss of other forms of N to the environment demands an appraisal of N flows within complete systems. The grassland N cycle is complex, with interactive controls over fluxes and transformations, and has the potential for considerable losses. Although there are data from experimental systems, a total comprehension of flows is not yet possible.Intensive dairy farming has a number of opportunities for leaks. A ‘model’ system in SW England has an annual input of 25.6 tonnes of N: of this only 20% is transferred into protein or milk, a further 46% is lost to the wider environment, 34% is as yet unaccounted for and much is recycled. Recent research has provided new techniques to decrease losses. To meet the joint requirements of production and environmental concerns we need to consider N flows and supplies on an integrated, whole farm basis, and to take better account of mineral N in the soil profile in relation to current crop demand, local climate and past sward management.

Notizen: Abstract. About 1.6 million tonnes of fertilizer N are applied to UK crops each year. In net terms, 10–60% of this is not taken up by the crop to which it was applied. Fertilizer N commonly doubles crop yield, but in the short term at least more than 90% of current production would be possible with only half normal use of N. However, costs of crop production other than fertilizer N are a large proportion of gross returns, so profits are sensitive to adjustments in N use and controls on N use could affect land values. Survey data show that compliance with current recommendations is good; recent improvements have come through restricting the use of N applications in autumn. Further improvements are possible by adjusting N use more fully for the extent to which past N applications have exceeded crop removal, and by better targeting the N used to improve protein concentrations of wheat grain. Research now in progress may provide insights into minimizing the crop N necessary for yield formation and the crop N left in the field at harvest, specifying the growing conditions which result in efficient N uptake from soil.

Notizen: Abstract. In south-east England, no relation between cereal yield and soil depth is shown by field estimates or harvesting microplots with depths to compact chalk of 23–121 cm. Differences in yield of ryegrass and wheat grown in cylinders containing artificial profiles with different thicknesses of topsoil, subsoil, chalk rubble and clean chalk from the Panholes series on Middle Chalk were attributed almost entirely to different amounts of nutrients. Chalk fragments supplied about 20% by weight of moisture to plants, and topsoil and subsoil about twice as much. Laboratory studies confirmed that fragments of Middle Chalk from near Wye (Kent, UK) hold about 20% water under tensions between 30 and 1500 kPa, but showed that topsoil and subsoil hold slightly less than this. The discrepancy in estimating water holding capacity arises because profiles over compact chalk drain only slowly from saturation. In this wet state they are very vulnerable to water erosion. It was also observed that ryegrass roots under water stress can penetrate well rammed chalk rubble, and that substantial amounts of water can rise 20 cm through solid chalk within a few days. It is concluded that soil losses resulting from erosion over normal porous chalks diminish cereal yields only slightly provided nutrient levels are maintained.

Notizen: Abstract. The effect of Agri-SC’ soil conditioner on the erodibility of loamy sand soils has been investigated at the Hilton experimental site, Shropshire, since March 1988. Factors measured have included runoff and erosion, soil structure, crust strength, splash susceptibility, aggregate stability, soil micromorphological properties, response to compaction and penetrometer resistance.Treatment decreased runoff and erosion rates, bulk density, splash erosion, crust strength and penetrometer resistance, and increased pore space and aggregate stability. The effects on crust strength, aggregate stability and bulk density were statistically significant. The results suggest that applications of ‘Agri-SC’ could have beneficial effects for soil conservation.

Notizen: Three trials examined the impact on chemical composition, leaf-stem ratio and bale temperature of applying a low-acid stabilizer and a Lactobacillus fermentation product at baling lo moist (20–25% moisture) lucerne Medicago saliva L.) hay. Treatments evaluated were lucerne baled at: 17–20% moisture (dry control); 20–25% moisture with addition of 200 g or 400 g 100kg-1 of a low-acid stabilizer, with 4·1 ml or 8·1 ml 100kg-1 of a Lactobacillus fermentation product; and 20–25% moisture with no treatment (wet control). In trial 1, low-concentration acid treatment was effective in limiting the increase in bale temperature of moist hay. In trials 2 and 3, bale temperature for low-concentration acid and Lactobacillus fermentation product-treated hay was similar to untreated moist hay In trial 3, higher application rates of either product were not effective in further reducing bale temperature. In trials 1 and 3, levels of neutral detergent fibre, acid detergent fibre, acid detergent lignin and acid detergent insoluble nitrogen were higher for moist hay than dry control. Nitrogen levels tended to be higher for moist hay. Leaf-stem data from trial 2 suggest that more leaves can be retained by baling relatively high-quality (late bud maturity) legumes at 20–25% moisture. In some circumstances use of a low-acid forage stabilizer for preservation of high-quality lucerne can minimize increases in temperature during storage of hay baled while moist (20–25%).

Notizen: Pastures of tall fescue (Festuca arundinacea) presumed to be free of the endophytic fungus (Acremonium coenophialum) had increasing levels of endophyte, averaging 4% per annum over periods of 9–12 years. Similarly, replicated plots sown at four levels of initial endophyte infection increased in infection over a 4-year period: for example, plots with a 27% initial level increased to 84%, and those with a level of 58% increased to 92% by the fourth year. Mowing plots to prevent seed formation did not affect the rate of change in infection percentage, except that plots with 0% initial endophyte began to show detectable levels in un-mown blocks, presumably as a result of contamination by seed from adjacent infected plots. By the fourth year of the study, fescue plant densities, measured by plant counts, as well as ground cover, were significantly higher in plots with high initial endophyte level. It is proposed that the change in infection percentage was due to enhanced survival of infected plants in mixed stands where there was intense competition for available moisture in conditions of drought.

Notizen: White clover content and herbage production in grass/clover swards were studied at contrasting altitudes in Wales. The lowland experiment (1) compared the performance of three clover varieties grown with four diploid perennial ryegrass (Lolium perenne) varieties with a range of heading dates. In the upland experiment (2) the productivity and persistence of Aberystwyth S184 (small-leaved) clover was studied in association with three perennial ryegrasses.In experiment I. clover content and dry matter production with Aurora (very early) ryegrass was superior to that with Frances (early), Talbot (intermediate) and Melle (late). Furthermore, the performance of Kent wild white clover (small-leaved) was better than that of medium-leaved Menna and Grasslands Huia. Averaged over two years (1985 and 1986) mean clover content of Kent was 22% compared with 9% and 10% of Menna and Huia.Performance of S184 clover during the five years (1986–90) of experiment 2 was better with Meltra (late tetraploid) than with Aberystwyth S23 (late diploid) and intermediate with Aurora. Clover stolon length and growing point number declined to a low level in 1988 but increased dramatically in 1989 and 1990 after cessation of applying fertilizer N.Results from both sites were related to animal performance data previously published. It is concluded that small-leaved clover varieties are needed to ensure a high proportion of clover in sheep pastures and also that choice of companion ryegrass can have a significant effect on the performance of the legume component.

Notizen: Herbage from forage rape (Brassica napus cv. Lair), harvested in the autumn, was separated into different morphological components and offered ad libitum to weaned lambs and adult sheep in two indoor pen-feeding experiments. In vivo. digestibility and the voluntary intake of herbage components were measured and related to chemical composition and in vitro digestibility. The organic matter digestibility of all plant components, especially of petiole, was high; lamina, 0·847: petiole, 0·892; upper stem. 0·865; lower stem, 0·771. Lambs and adults digested ‘leaf’ (0·83) vs 0·846) or ‘stem’ (0·782 vs 0·789) equally well. Both lambs and adults ate much less of the components or of whole crop than would be predicted with grass crops of similar digestibility or fibre content. With the exception of lamina, intake was closely related positively to digestibility and negatively lo fibre content. Low intakes of lamina were associated with high concentrations of glucosinolates. In vitro digestibility values obtained on small samples of forage show that the process is adequate for the prediction of in vivo digestibility.

Notizen: Two diets were compared: perennial ryegrass (Lolium perenne L.) silage and perennial ryegrass/white clover (Trifolium repens L.) silage, in each case fed ad libitum, without supplementation, to lactating dairy cows. The comparison was made with silages cut on each of four dates. The crops were wilted to a dry matter content of at least 256g kg-1 and no additives were used.The grass/clover silages were well preserved at all four cuts. The grass was well preserved at three cuts, but, at a May cut, the grass silage was less well preserved and less digestible than the grass/clover silage. When the May silages were fed, milk yield was higher with grass/clover than with grass. Taking the experiment as a whole, however, milk yield and composition were similar on the two diets. The grass/clover silages had a lower proportion of cell wall and their intake by dairy cows was consistently higher than that of the grass silages.It is concluded that perennial ryegrass/white clover crops can be ensiled successfully and fed successfully, with high intake, to lactating dairy cows, but it should not be assumed that cows will give more milk than when fed equivalent all-grass silage.

Notizen: Herbage characteristics were studied over years 4–6 (1988–90) in three perennial ryegrass (Lolium perenne L.) varieties as grass-only (200 kg N ha-1) and grass/clover (Trifolium repens L.) swards which received 75kg N ha-1 in 1988 and 0kg N ha-1 in 1989 and 1990 when continuously stocked with sheep. Mean total annual herbage production of Aurora, a very early flowering variety, was 11% more than that of late-flowering Aberystwyth S23 due to 21% higher growth as grass/clover pasture. The grass/clover sward of Meltra, a tetraploid late-flowering variety, out-yielded S23/clover by 17%. Herbage production of grass/clover was 86% of that of grass only in 1988 but only 54% of the grass-only swards averaged for 1989 and 1990. In vitro organic matter digestibility (OMD) of Meltra was 38g kg-1 OM and 27g kg-1 OM higher than that of S23 and Aurora respectively. OMD of grass/clover was 15g kg-1 OM higher than that of grass only during the post-weaning period. Herbage intake was positively correlated with OMD of herbage.The herbage attributes were related to lamb performance reported previously. Lamb output was positively correlated with intake of digestible organic matter.Differences between the three varieties in herbage characteristics were greater as grass/clover than as grass-only swards, reflecting their compatibility with white clover. In this respect Meltra was the best and S23 the poorest variety.

Notizen: Mineral availability and status in body tissues was examined with four rumen-fistulated steers arranged in a Latin-square change-over design. The steers were fed perennial ryegrass herbage from a pasture fertilized with four Na treatments: 0 (Nil), 32 (Low), 66 (Medium) or 96 (High) kg Na ha-1 yr-1. Na fertilizer increased herbage contents and intakes of Na, Mg and Ca but did not affect intakes of K, P and S. Herbage K:Na and K:(Ca+Mg) decreased in direct proportion to the amount of Na fertilizer applied. With increasing dietary Na intake, the Na content of saliva increased and the K content decreased. There was an increase in Na and a reciprocal decrease in K contents of rumen fluid with increasing dietary Na. Blood plasma Na contents were greater when the Na-treated herbages were fed than in the Nil treatment. There was no effect of treatment on blood plasma K content. Increasing dietary Na increased urinary Na but did not affect urinary K. Faecal mineral concentrations of Na, Ca, P and S were increased by increasing dietary Na, whereas K content was reduced and the Mg content was unaffected. There was no difference between treatments in the proportion of mineral rapidly solubilized, except Na which increased with increasing dietary Na content. The fractional rate of degradation was greater for Na, K, and Mg than for Ca and P. Based on effective solubilization, minerals were ranked in the order K 〉 (Mg = Na) 〉 Ca 〉 P, and treatments were in the order Medium 〉 (High = Low) 〉 Nil. Increasing Na intake increased Ca but not P or Mg availability and increased the uptake of all three minerals.

Notizen: Two 1·0 ha plots of a late-heading diploid perennial ryegrass (var. Contender) and a late-heading tetraploid ryegrass (var. Condesa), and two 1·4 ha plots of the tetraploid with Aberystwyth S184 small-leaved white clover, were direct sown in May 1987. Over the three years 1988–90 they were continuously stocked by Mule ewes with Suffolk-cross twin lambs, from early April to the end of August, at a target sward surface height (SSH) of 4–6 cm on one set of plots (constant swards) and, on the other set, al 4–6 cm rising after June to a target 6–8 cm (rising swards). The heights were achieved by variable stocking. Fertilizer N was applied only to the grass plots at the rate of 150- 180kgN ha-1 annually.SSH was mainly within the target 4–6 cm, after higher initial heights at turnout in 1988and 1990. Mean heights of the constant swards (April- August) averaged 5·53, 4·43 and 5·04cm in the three years. The rising swards (July-August) increased in height over the constant swards by an average of 0·88, 0·48 and 0·55 cm, in successive years.Clover content of the herbage mass dry matter in the grass/clover swards increased over each grazing season to average 13·0, 26·5 and 21·2% in the three years, with a high mean stolon density of 130 in m-2 in August 1990. Ryegrass tiller densities in year 3 were 23% higher in the diploid than in the tetraploid swards, which had 43% more than the 10000 tillers m-2 of the tetraploid ryegrass/clover swards.It is concluded that the combination of a densely stoloniferous small-leaved clover with the open growth habit of a tetraploid ryegrass can achieve swards of high clover content under continuous sheep stocking.

Notizen: The effects of different spring defoliation managements on potential harvestable seed yield and seed yield components of three contrasting white clover cultivars were assessed. The small-leaved cv. S184 produced more but smaller inflorescences than the large-leaved cv. Olwen and Menna, a medium-leaved cultivar. Cultivar Olwen, however, produced more ripe and brown (nearly ripe) inflorescences with more florets, seeds per floret and a higher seed yield per ten inflorescences than the other cultivars. Potential harvestable seed yield and individual seed yield components were only influenced by defoliation after bud emergence, as defoliation before bud emergence had no effect on seed yield components. Defoliation after bud emergence had a similar effect on all cultivars: the number of ripe inflorescences was unaffected by defoliation but the number of brown and therefore harvestable (ripe + brown) inflorescences was highest following defoliation three weeks after bud emergence. Florets per inflorescence, seed per floret, 1000 seed weight, seed yield per ten inflorescences and potential harvestable seed yield were not influenced by defoliation after bud emergence. Season had a significant effect on seed yield components and influenced the effect of defoliation treatments, emphasizing the importance of climate in white clover seed production. The results are discussed in relation to the spring defoliation of white clover seed crops, harvesting techniques and the provision of guidelines for optimizing seed yield.

Notizen: Two experiments were conducted to examine the relationship between sward surface height, herbage intake and liveweight gain in beef cattle grazed on pasture. In Experiment 1, two ‘animal types’ (18 Charolais × Angus steers and 18 Friesian bulls) were continuously grazed for 22 days during the late autumn on replicated swards maintained at sward surface heights of 6, 10 and 15 cm. Herbage intakes, assessed from the faecal concentration of chromium delivered from an intraruminal controlled release capsule and the in vitro digestibility of hand-plucked herbage samples, were curvilinearly related to sward height (r = 0·76, p〈0·0·01). Average liveweight gains were 0·02, 0·61 and 1·31 kg d-1 (P 〈0·05) and increased linearly (r= 0·84, P 〈0·001) with sward height. The maintenance organic matter intakes of the steers and bulls, with initial mean (± s.e.) live weights of 225 ± 15 kg and 172 ± 15 kg respectively, were estimated to be 3·6 and 3·5 kg d-1 respectively. In Experiment 2 (spring) 36 cattle, including 35 of those used in Experiment 1, were reallocated to sward heights of 5, 10 and 15 cm using the same design as for Experiment 1. Average liveweight gains were 0·94, 1·57 and 1·68kg d-1 (p 0·05) and were curvilinearly related to sward height (r= 0·093, p 〈0·05). Maintenance intakes could not be reliably extimated for the cattle in Experiment 2 because few animals had liveweight gains close to zero. These trials confirm that liveweight gain in continuously grazed finishing steers and bulls increases with sward surface height to maximum of 8–10cm with spring ryegrass/white clover pastures while, in autumn, swards of 12–15cm height are required to achieve maximum performance.

Notizen: Seven cultivars of white clover (Trifolium repens L.) (Kent, S184, Huia, Menna, Donna, Alice and Nesta) and a commercial mixture, ‘Ensign’, were strip-seeded into an upland perennial rye-grass (Lolium perenne L.) sward in late June 1986. Swards were first grazed by sheep, either on 5/6 August (early) or on 19/20 August (late) and then every 14–21 days (frequently) or 28–42 days (infrequently) during 1986, followed by a common grazing regime in 1987. During April to mid-June 1988 the swards received either a moderate amount of nitrogen or none and were cut frequently or once only in mid-June. Growth of individual seedlings was assessed before and after grazing during 1986 and stolon accumulation and distribution and sward colonization were assessed during 1987 and 1988.All cultivars emerged rapidly and satisfactorily and there were no consistent significant differences in the overall dry matter accumulation per seedling during establishment. During the first autumn the proportion of the aboveground biomass removed during grazing was smallest in Kent (c. 20%) and largest in Nesta (c. 40%). Kent and S184 produced most leaves and stolons and the greatest length of stolons per seedling and per individual stolon, and Nesta and Alice the fewest leaves and stolons and shortest stolons. Seedlings grazed early had heavier and longer stolons than those grazed late; those grazed frequently had more leaves, stolons and growing points than those grazed infrequently, especially following early grazing.During 1987 Kent and S184 had consistently the largest number of stolon growing points, and weight and length of stolons per unit area; these two cultivars and Nesta also colonized the sward more rapidly than the other cultivars. All cultivars contributed substantially and similarly to herbage production in late September. There were no residual effects of the 1986 treatments after the summer of 1987.During 1988 additions of nitrogen fertilizer at 100 kg N ha-1 or allowing the herbage to remain undefoliated between mid-April and mid-June both independently halved the number of stolon growing points per unit area; together they reduced it by 80%. Nitrogen also, on average, halved stolon weights but less so in Nesta, Alice and Huia and more so in all other cultivars. Infrequent defoliation greatly decreased stolon weights in Kent and S184 but had no significant effects on the other cultivars. Sward colonization was almost complete by June and entirely so by October for all cultivars in all treatments.Implications of the results for the after-management of strip-seeded white clover are discussed.

Notizen: Three white clover cultivars, S184 (small-leaved), Menna (medium-leaved) and Olwen (large-leaved), were sown at a seed rate of 3 kg ha-1 under spring wheat cv. Tonic. In the spring of the two following years, there were three pre-bud emergence mechanical defoliation treatments on which were superimposed four post-bud emergence treatments giving a total of twelve cutting treatments. Pre-bud emergence, plots were either cut twice (at approximately two weeks before bud emergence and at bud emergence), cut once at bud emergence or not cut. To each treatment were applied four post-bud emergence treatments: plots were not cut or cut once (one, two or three weeks after bud emergence). Counts of the total number of inflorescences and of the proportions in various ripeness categories were made throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. Overall, inflorescence numbers were greatest in cv. S184and least in cv. Olwen. Defoliation before bud emergence had no effect on inflorescence production; however, it was significantly influenced by defoliation after bud emergence. Although delaying the initial development of the crop, inflorescence numbers of all cultivars were highest in both years following cuts two and three weeks after bud emergence. Optimum harvest date was not affected by defoliation or cultivar, numbers of ripe inflorescences in both years reaching a peak at the end of August. The number of brown inflorescences, which may also contribute to seed yield, reached a peak in both years in late July. Seasonal differences in inflorescence production were again observed, emphasizing the difference between first and second year crops and importance of climate in while clover seed production. The implications of these differences in numbers and proportions of inflorescences in various ripeness categories under different defoliation regimes are discussed in relation to seed crop management in the UK.

Notizen: Two non-destructive techniques for estimating herbage mass (dry matter yield) were evaluated during the growing season of 1988, from April to September. Samples were collected from four sites, with ten observations made on twenty-five days at each site, giving a total of 612 sample units. Observations were obtained from each unit, either with a plastic rising-plate meter (335) or with a metal rising-plate meter (227). In addition, measurements with a single-probe capacitance meter (Pasture Probe) were also made on all units. The usefulness of the non-destructive methods for predicting the actual yield was evaluated by calibrating them by means of regression on the yield determined by mowing 1·5-m2 quadrats, weighing, subsampling and drying the grass. The yield measurements were logarithmically transformed to correct for the proportionality of the residual variance with the mowed dry matter yield. Logarithmic transformation of the sensor measurements improved the linearity of the calibration relationships. The combination of one rising-plate meter and the Pasture Probe resulted in a linear and additive model with a larger adjusted R2 than models with just one of these two sensors. The addition of the predictors ‘external moisture’ (e.g. dew), ‘day number after mowing’ and ‘site number’ significantly increased the goodness of fit of many models. In some models addition of the logarithm of the ‘dry matter percentage’ was significant. Other predictors in these models such as “Julian day number” and “grazing” proved not to be significant. The adjusted R2s in the best models for the metal and the plastic discs were 89·7% and 87·3% respectively. The corresponding coefficients of variation were 26·2% and 26·1%.The results show that further research is necessary to refine the techniques or to develop new techniques to estimate the dry matter yield, before the sensors can be usefully integrated into a management system.

Notizen: Sixteen Friesian cows were given four dietary treatments in a 4 × 4 Latin square experiment with a 2 × 2 factorial arrangement of treatments. The diets consisted of grass silage ad libitum plus 2 kg of hay per day and two types of concentrates of either barley or a mixture of barley, oats and fibrous by-products [200,200 and 600 g per kg dry matter (DM) respectively], with two protein contents. For the low-protein diets, barley- (B) and fibre-based (F) concentrates were given without protein supplements, while for high-protein diets 1 kg of both concentrates was replaced with fish-meal (FM). The concentrates were given at the rate of 9kgd-1 for the cows (n= 12) and 8kg d-1 for the heifers (n= 4).The cows given the F diets tended (P 〈 0·10) to have a greater silage dry matter intake and produced 1·5kg d-1 more (P 〈 0·05) milk with a lower (P 〈 0·05) protein content than those given the B diets. Increasing dietary crude protein concentration with FM had no effect on feed intake but resulted in significant increases in milk yield (P 〈 0·01), milk protein content (P 〈 0·05) and yields of milk constituents. The response in milk yield to FM tended to be greater with barley than with fibrous supplement (+2·5 vs+ 1·5kgd-1). Compared with B diets, the greatest relative increase occurred in lactose yield (0·07) when the corresponding F diets were fed, while FM produced the greatest response in protein yield (0·12). The calculation of the utilization of metabolizable energy (ME) for milk production showed that both the feeding of a concentrate consisting of different carbohydrate sources and inclusion of fish meal improved the utilization of ME, the effects being partially additive. It is concluded that the nutrient supply to the cow's tissues can be modified by the source of carbohydrate and protein supplementation as indicated by different responses in the yield of milk constituents. The production response to protein supplementation may depend on the source of carbohydrate in the concentrate.

Notizen: A sigmoid equation that accurately describes pasture growth is presented. The equation has three parameters that can be estimated either statistically from experimental results or algebraically from physiological simulation models. The equation produces satisfactory statistical results and it can account for different environmental conditions, through adjustment of parameter values, making it ideal for incorporation into grazing models when a simple but flexible equation is needed.

Notizen: Two field experiments were carried out at North Wyke, Devon in 1985 (Experiment A) and 1986 (Experiment B) to investigate the effectiveness of either cutting or rotational sheep-grazing managements for raising the clover content of clover-depleted swards. Subplots were pretreated in March with (a) propyzamide at 0·4kg a.i. ha-1, (b) chlorpyrifos at 0·72 kg a.i. ha-1 and methiocarb at 0·22 kg a.i. ha-1, (c) carbofuran at 1·3 kg a.i. ha-1, or (d) not so treated, in order to reduce grass tiller density, control insect and mollusk pests, or control all invertebrate pests respectively (a-c), Carbofuran was not applied to swards that were to be grazed subsequently. The propyzamide pretreatment (a) significantly reduced the quantity of herbage dry matter (DM) grazed and the silage DM yields in both years, but raised the numbers of active clover buds, and clover stolon density and its weight in 1986, though not in 1985, The pesticide package (b) raised the quantity of herbage DM grazed in both years, and the silage DM yield in 1986, Carbofuran (c) raised silage yields in 1985. Neither pretreatment (b) nor (c) significantly affected clover performance. In comparison with sheep grazing, cutting showed a trend to higher DM yields, and significantly raised clover stolon density and weight in both years, and active bud numbers in 1986. The periodic sheep grazing management included recovery intervals of 14 d and 35 d. In 1986 (but not 1985) the longer recovery interval raised herbage DM consumption, but had no effect on clover development. The cutting management included nitrogen inputs of either 100 kg ha-1 in March, or none. N input raised annual DM yields in 1986 (but not 1985) but did not affect clover DM yields or performance in either year.The experiments at North Wyke were supported by on-farm experiments using exclosure cages at ten sites in 1985 and nine in 1986, in Yorkshire, Wales, the Midlands and Devon. In both years, application of propyzamide as in treatment (a) reduced DM yields (P〈0.001) and raised the proportion of clover (P〈0.001) in May harvests. The density of active clover buds (P〈0.05), stolon density (P〈0.001) and stolon weight (P〈0.001) were increased by October. A combined carbofuran and methiocarb treatment significantly (P〈0.001) increased herbage yields, but did not affect measures of clover performance. Unlike the main experiments, a comparison of grazing (outside the cages) and cutting management (within the cages) showed no effect on clover development.It was concluded that cutting, or rotational sheep grazing with a long recovery interval, would promote clover development in the clover depleted sward. Though successful in the overall assessment, application of propyzamide gave highly variable results on different sites and was not sufficiently reliable.

Notizen: The growth of clonally propagated clover plants (Trifolium repens) in the glasshouse was compared with their growth under canopies of Tropaeolum peregonium with or without supplementation from red light emitting diodes (LEDs) directed at the youngest node bearing a fully expanded leaf. The T. peregonium was grown over a net support so that its roots did not meet those of the clover. A similar experiment was set up in a permanent grassland using canopy shade from various grass species (Holcus lanatus, Lolium perenne and Agrostis stolonifera) with and without supplementation. The LEDs increased the ratio of red to far red radiation (R/FR) received by the treated node with no apparent increase in photosynthetically active radiation (PAR) during the day.The morphogenetic effects of canopy shading (notably fewer branched nodes and less well-developed branches) were largely removed by supplementation so that the supplemented plants came to resemble those grown in full daylight, particularly in the glasshouse experiments. The results highlight the Importance of the radiation environment at the base of the canopy in the morphogenetic responses of plants to putative competition, and the data are consistent with the hypothesis that responses are communicated acropetally along the stolon.

Notizen: Performance of continuously stocked Mule ewes nursing Suffolk-cross twin lambs over three grazing seasons, between April and August, was compared on swards of N-fertilized diploid perennial ryegrass (D), tetraploid perennial ryegrass (T) and tetraploid perennial ryegrass with white clover (TC), the latter receiving no fertilizer N. Sward height was maintained by variable stocking rate close to a target of 4–6 cm (constant treatment) from turnout and compared in July and August with a rising sward height treatment (target 6–8 cm).Lambs on TC swards had significantly higher (P 〈0·001) liveweight gains compared with lambs on T swards by 41 gd-1 in April–June and by 68gd-1 in July-August. Live weight and body condition score of ewes in August were significantly higher (P〈0·001) on TC compared with T swards, by 11·3 kg and 0·75 respectively. Rising sward heights in July–August increased live-weight gain of lambs compared with constant sward heights by 102, 39 and 54gd-1 in consecutive years, associated with sward height increases of 0·9, 0·5 and 0·6cm respectively. Rising sward height increased ewe live weight and body condition score by 5·1 kg and 0·3 respectively, compared with results from constant sward heights. Effects of sward height and sward type were additive.T swards had a significantly (P〈0·01) 16% greater overall lamb output than the D swards due mainly to a 10% higher achieved stocking rate. Stocking rates of ewes on TC vs T swards were 40, 13 and 12% lower in April-August in successive years. The higher liveweight gain of lambs on the TC swards resulted in lamb outputs of 76, 105 and 101% of the T swards in successive years, showing that grass/clover swards containing over 20% clover could produce similar lamb output ha-1 to grass swards given 150–180 kg N ha-1.

Notizen: In a two-year study, set stocked dairy cows were offered a mixture of brewers grains and sodium hydroxide-treated straw (1:1 on a dry matter basis)for 1 h daily. The experiments lasted for 20 and 19 weeks, mean supplementary (buffer) feed dry matter intakes were 3·0 and 3·4 kg d-1 and mean sward heights (rising plate meter) were 4·9 and 4·7 cm in 1988 and 1989 respectively. The control group received no supplementation. The buffer feed significantly increased milk yield (26·3 vs 24·6 kg d-1 and 28·6 vs 26·3kg d-1 in 1988 and 1989 respectively), increased liveweight gain (0·27 vs 0·13 kg d-1 and 0·27 vs 0·17 kg d-1) and increased effective stocking rate (5·17 vs 4·69 cows ha-1and 5·10 vs 4·53 cows ha-1). There were no significant effects on milk composition. The greatest responses in milk production were found in the late grazing season.

Notizen: Liquid treatments to accelerate drying were applied to lucerne under laboratory conditions by brief immersion (∼3s) of cut shoots. Aqueous solutions of the alkali metal carbonates Li2CO3, Na2CO3 and K2CO3 were found to reduce drying times to 33% moisture content (MC) on a dry weight basis (dwb) by 45%, 55% and 65% respectively. Effectiveness was related to the ionic radius of the cation.From a range of potassium salts (KCl, K2CO3, KHSO4, KOH, K2SO4) in aqueous solution, the only useful reductions in drying time to 33% MC (dwb) came from the alkaline KOH (68%) and K2CO3 (65–76%).It is considered that K+ has a specific function in increasing water loss through the plant cuticle and that association with CO32- provides the high pH necessary for this activity.An aqueous solution of K2CO3 (0·16 M) gave greater acceleration of drying than the organic solvent petroleum ether and no benefit was gained by combining these treatments. Addition of a surfactant did not improve the effectiveness of K2CO3 as a desiccant but mixing with a rape-seed oil emulsion reduced the drying time to 33% MC (dwb) by 11% relative to K2CO3 alone.Under field conditions K2CO3 as an aqueous solution gave only small reductions in the drying time to 33% MC and effectiveness was reduced by the addition of the rapeseed oil emulsion.Better results with K2CO3 (aq) might have been achieved with a more ventilated swath structure but the results strongly suggest that the oilseed rape emulsion is unlikely to improve the effectiveness of K2CO3 under field conditions.

Notizen: The energy value and chemical composition of 70 herbages harvested over two years as either spring primary growths of increasing maturity (n= 32), summer regrowths (n= 14) or autumn regrowths of increasing maturity (n= 24) are reported. The herbages, which were dominated by perennial ryegrass, were harvested from commercial grassland on four sites in England in1986 (year 1) and 1987 (year 2). Digestibility and energy values were determined in vivo using wether sheep.In year 1, autumn regrowths had significantly (P 〈 0·05) lower neutral detergent fibre concentrationsthan summer regrowths, and lignin was lower (P 〈 0·05) in spring than in summer herbages. In year 2, autumn herbages had significantly(P 〈 0·05) higher concentrations of crude protein and hemicellulose than summer and autumn herbages. Spring herbages had higher concentrations of water-soluble carbohydrates than summer (P 0·01) and autumn (P 〈 0·001) herbages.A higher (P 〈 0·05) metabolizable energy (ME) concentration was observed in spring compared with summer herbages in year 2 and in general there was considerably more variability in the values for the spring growths, ME content fell with increasing maturity in spring growths(0·046 and 0·035 MJ kg-1 DM per day; years 1and 2 respectively) and this decline was 3–4 times faster than for autumn-harvested material (0·012 and 0·017 MJ kg-1 DM per day; years 1 and 2 respectively). In both years only immature spring herbages consistently produced ME contents in excess of 11·9 MJ kg-1 DM.For 15 of the herbages the proportion of gross energy intake (GEI) lost as methane was measured directly using respiration chambers. The mean methane energy loss was 0·07 of GEI (range 0·057–0·082). A commonly used publish equation for predicting methane energy loss was shown not to be appropriate, although no relationships could be established between methane energy loss and either energy digestibility in vivo or chemical composition.

Notizen: Greenhouse and field experiments were carried out to study the seed development and seed yield potential of three populations of Italian ryegrass (Lolium multiflorum Lam.). These included an ecotype (Bb 1276) collected in the Lombardy Plain region of northern Italy, cv. Tribune, which was derived from this ecotype, and cv. Lemtal, a widely used cultivar from Belgium. Artificial seed shedding techniques in the green-house study showed that Bb 1276 began shedding seed at a higher moisture content than cv. Tribune which in turn was higher than cv. Lemtal. The pattern and rate of shedding was similar for all three populations and generally Bb 1276 and cv. Tribune gave a greater proportion of shed seed than cv. Lemtal. Although the pattern of decline in seed moisture content was similar for all three populations, generally cv. Lemtal had a higher moisture content than cv. Tribune with Bb 1276 the lowest. Cultivar Lemtal had the highest mean 1000 seed weight, and Bb 1276 the lowest, with cv. Tribune intermediate. The field study involving cv. Tribune and cv. Lemtal showed that with the exception of 1000 seed weight, which for cv. Tribune was some 6% lower than that of cv. Lemtal, all the seed yield components were similar. Seed yields taken every 3 days after the standing crop had reached 50% moisture content showed that both cultivars increased in yield until harvest 3. After this date the seed yield of cv. Lemtal remained stable up to harvest 5 while that of cv. Tribune declined. The maximum seed yield of cv. Tribune was achieved at a seed moisture content of 42·9% while that of cv. Lemtal remained stable from 42·3% to 37·5%. The seed moisture content of the two cultivars again showed a similar pattern of decline but it was not possible to show consistent differences between cv. Lemtal and cv. Tribune. The 1000 seed weight of cv. Tribune was lower than that of cv. Lemtal, and the maximum seed weight of cv. Tribune appeared to be achieved earlier. Germination counts taken after harvest showed both populations exhibiting a high level of post harvest dormancy. Later counts taken 3 months after harvest were significantly higher than those taken earlier and there were no differences between cultivars or harvests.The results are discussed in relation to the potential for selecting for improved seed yield potential in Lolium multiflorum Lam. Populations from northern Italy and suggestions are made for maximizing the harvested seed yield of cv. Tribune.

Notizen: Three white clover cultivars, S184 (small-leaved), Menna (medium-leaved) and Olwen (large-leaved), were broadcast or sown in 15, 30 or 60 cm drills at a seed rate of 3 kg ha-1. The three cultivars were either sown without a cover-crop or sown under a cover-crop of spring barley (cv. Crescent) or peas (cv. Countess). The effects of these methods of establishment on the stolon growth and components of seed yield were subsequently measured.Stolon growth and development was influenced by row spacing, cultivar and season. The overall plant response at all but the widest row spacing (60 cm) was to increase stolon growth such that inflorescence production, the number and proportion of ripe inflorescences and the other seed yield components were unaffected by row spacing. Cultivars differed in their response to row spacing. Cultivar Olwen produced most inflorescences and more ripe inflorescences when broadcast, cv. S184 when sown at 60 cm row spacing and cv. Menna at 15 or 30 cm row spacing. Cultivars also differed in their response to cover-crop, with cvs Menna and S184 producing more inflorescences and more ripe inflorescences when sown under barley and peas than when pure sown. The inflorescence production of cv. Olwen was not influenced by cover-crop.The relationship between vegetative and reproductive growth is discussed in relation to establishment, cultivar and climate and the possible implications for the establishment of white clover seed crops in the UK.

Notizen: The definitions of the grass growing and grazing seasons as climatic parameters are investigated using a grass growth model. Taking a mean air temperature of 6°C to define the start and end of the growing season at nine UK stations, the model indicates the following: (1) dry matter growth rates at the start are 6 to 9 times greater than those at the end; (2) growth rates at the start of the growing season are higher in those areas where it begins late (i.e. late March/ early April) than in areas where it begins earlier (i.e. late February/ early March). When defining the grazing season in terms of a delay after the start of the growing season, the model indicates that (3) growth rates at the start of the grazing season are higher in upland areas and in areas where the growing season begins late than in lowland areas and in areas where the growing season begins early.A definition of growing season in terms of growth rates shows that 5 and 8°C are more suitable temperatures to define the start and end than 6°C.Grazing season was more adequately described using growth rates than in terms of a delay after the start of the growing season.

Notizen: Perennial ryegrass, harvested as second-cut material on 10 and 11 July 1990, was treated with either formic acid at 31 t-1 or an acid-salt type additive at 61 t-1 and ensiled in roofed 150 t bunker silos. Subsequently both silages underwent a predominantly lactic fermentation. Nevertheless the acid-salt-treated silage had a significantly higher quantity of formic acid (19 vs 12 g kg DM-1) and significantly lower levels of lactic (98 vs 118 g kg DM-1) and acetic acid (11 vs 17 g kg DM-1) compared with formic acid-treated silage. In-silo losses and effluent production were similar.Each silage was individually fed to 10 October-calving Friesian dairy cows (average weight 565 kg) from weeks 2 to 15 of lactation, together with 3 kg d-1 of a compound feed containing 190 g kg DM-1 crude protein and with an estimated metabolizable energy content of 12·6 MJ kg DM-1. The acid-salt additive had no significant effect on silage DM intake, daily milk yield, milk protein or cow liveweight change, but significantly increased milk butterfat content compared with formic acid-treated silage.It is concluded that the acid-salt type additive produced little difference in terms of either silage fermentation or animal performance compared with formic add treatment.

Notizen: Stable hybrids were produced between tetraploid perennial and Italian ryegrasses derived from commercial varieties and germplasm introduced from European collections. Spaced plant characteristics were used to select Fl plants for the production of F2 families which were assessed in small plots for growth and quality traits. Ten of the 19 selected hybrid families were based on perennial ryegrass collected from the Zurich Uplands. The influence of this parental material in improving vegetative growth during early spring, late summer and autumn was demonstrated. Its use in improving feeding value by increasing the water-soluble carbohydrate content of hybrids was also shown. Consequently, selected hybrid varieties based on this new genetic resource showed considerable improvements in seasonal growth and quality over the older hybrid variety Augusta and Italian ryegrass variety RvP.

Notizen: The effects of two commercial cellulase/hemicellulase enzymes derived from Trichoderma reesei on silage fermentation were investigated in three laboratory-scale experiments. In Experiment 1, perennial ryegrass (Lolium perenne) was treated with enzyme A at the rates of 0, 0·125, 0·250, 0·500 and 0·750 cm3 kg-1. In Experiment 2, Italian ryegrass (Lolium multiflorum) was treated with the same enzyme at the rates of 0, 0·250 and 0·500 cm3 kg-1 and with 85% formic acid (3·5 cm3 kg-1). In Experiment 3, perennial ryegrass was ensiled untreated, with enzyme A (0·250 and 0·500 cm3 kg-1) and with 0·200 and 0·400 cm3 kg-1 enzyme B which also contained glucose oxidase. All silages were well preserved. In general enzyme treatment reduced pH and the contents of ammonia nitrogen, neutral detergent fibre and acid detergent fibre, whereas the contents of water-soluble carbohydrates, acetic acid, lactic acid and ethanol were increased.

Notizen: A field experiment was conducted to clarify the factors responsible for poor seed set in four white clover (Trifolium repens L.) cultivars. Although the mean number of ovules per floret was 5·18–5·29, the average number of seeds per floret was found to be only 1·23-1·82. A stainclearing technique was used to examine the cytoplasmic state of the embryo sac in intact, unfertilized, mature ovules and it was found that 28–33% of ovules per carpel were sterile. The abortion rate of fertilized ovules and immature seeds (7 days after pollination) ranged between 32 and 34%. Beyond this period, it was observed that only a very small proportion of the total seeds were lost. The observation of high pollen fertility and a high pollen load strongly suggests that poor pollination does not account for the reduced number of seeds per floret. A ‘nutrient competition’ hypothesis was proposed for high ovule sterility and post-fertilization abortion of developing seeds.

Notizen: Observations have been made which suggest that clover is more effective than ryegrass in developing rapid improvements in soil structure. To test this hypothesis, grass, grass/clover and clover swards were grown in undisturbed field cores. Significant differences in drainage rates and plant biomass production, and visible changes in soil structure, all supported the hypothesis that clover improves structure rapidly, but there were no significant differences in bulk density, porosity or aggregate stability between the treatments. Soil moisture characteristic curves of soil/peat/grit compost planted with grass, grass/clover or clover and grown for two years indicate that a more free-draining structure develops under clover than under grass due to a higher ratio of macro- to micropores.