ALBERT

Notes: Abstract. The data from the national project to monitor water erosion has mostly been treated in an aggregate form, because in many of the monitored transects in any year too few fields were eroded for the data to be split into its component parts. However, in crop year 1983 erosion affected enough fields in two localities with contrasting soils for their data to be compared. Rainfall patterns in the two localities were similar. The transects covered a sandland area in Nottinghamshire and an area of clayland in and on the margins of Bedfordshire. Compared with the clayland, rilling of the sandland was widespread, related to the greater range of crops grown there, and more severe. On clayland, rills were mainly confined to valley floors, and slopes flanking these valleys generally had lower gradients than those on the sandland. On sandland, slopes were steeper in eroded fields drilled to winter cereals than they were in fields planted to potatoes or sugarbeet. Such field- based studies hint at the complex interactions of rain falling on a cropped field. Erosional thresholds are not static. The areas of fields affected by erosion and deposition were mostly very small. This helps us understand why the farmer often considers erosion unimportant.

Notes: Abstract. The electrical conductivity of pig slurry suggests that addition of this waste to soils in arid and semi-arid areas could cause salinization. Changes in electrical conductivity and soluble salt concentration in two calcareous soils indicated a salinity risk after 24 months of pig slurry addition at rates of 400 m2/ha/yr or more. Salinity risk increased with soil water-holding capacity. Water-soluble potassium concentrations showed a greater increase than other cations in the soils because of the large amount present in the slurry. The proportion of soluble potassium in the soil depended on the soil's cation exchange capacity and on the composition of the clay fraction.

Notes: Abstract. Spatial averaging of data before or after modelling has important implications for large area land evaluation studies. Two procedures are evaluated for the spatial averaging of weather and soil moisture data before and after modelling (procedures A and B, respectively). The Thiessen polygon weighting technique is applied to a network of weather stations to derive daily weather values for the period 1955 to 1985 for 12 selected Agroecological Resource Areas (ARAs) on the Canadian prairies. These values are used in the model for procedure A. The components of the soil moisture balance for spring wheat are estimated with a budgeting model, assuming wheat is grown continuously for 30 years on soils with available water-holding capacities (AWCs) of 150 and 250 mm. In procedure B, the data from individual stations are used as input to the model and the same Thiessen polygon weighting coefficients are applied to the output variables. A comparison of the two procedures shows no significant difference for temperature-related variables such as frost dates, harvest date and cumulative potential evapotranspiration. The differences for moisture-related variables (soil moisture content at sowing, cumulative actual evapotranspiration, runoff and deep drainage) are often statistically significant, but the absolute differences are less than 10 mm at probability levels ranging from 10 to 90%. For many practical applications the two procedures give similar results.

Notes: Abstract. The area covered per unit mass (Am) of a mulch material is an important factor for controlling erosion, especially in the humid tropics. Values of Am for mulching materials commonly available in S.E. Nigeria - guinea grass, banana leaves and palm leaves - were found to be 0.00035, 0.00038 and 0.00020 haAg, respectively. These values are within the range (0.0001–0.0007 ha/kg) reported for other mulching materials elsewhere. They can be fitted into existing equations to determine the amount of mulches required to achieve any predetermined ground cover percentage.

Notes: Abstract. Information on land resources and the capacity of land to support agricultural production is a prerequisite for the formation of sound agricultural policies. This paper summarizes Canadian experiences in developing national and regional land evaluation systems. Potential users expected the system to estimate the degree to which changes in biophysical and socio-economic conditions would alter options for land use and production, and to provide a context for more detailed analysis.A broad-scale land evaluation system was designed to serve the needs identified by representative user groups. Two prototype systems were developed from available information to test the major features of the system design. Neither prototype was complete; one was national in extent and capable of addressing issues of national and provincial importance, the other covered a sub-provincial area but allowed for more detailed evaluation of the effects of soil modifying processes. A full range of applications was demonstrated using one or other of the prototype systems. As a result of this project, the broad-scale land evaluation system design was improved and verified, ongoing research and data collection activities were adjusted to ensure that they meet the needs of a macroscale land evaluation system, and approaches were developed to overcome problems of land evaluation system development.

Notes: Abstract. The influence of trampling on the soils of the St James Walkway was studied during 1985 by comparing ‘on’- and off-track sites. Trampling increased the average soil bulk density by 0.3 g/cm3 at 0–5 cm depth and by 0.1 g/cm3 at 10–15 cm depth. Trampling increased the average soil shear strength by 11 kPa at 0–5 cm depth and by 6 kPa at 5–10 cm depth. All mineral soils were compacted to some extent by trampling. The podzolized high country yellow-brown earths (Dystrochrepts) were the most affected because their organic topsoil was truncated. Their exposed subsoil was however more resistant to further damage than their topsoil. Organic soils (Medihemists) were not compacted but their very low shear strength and high moisture content make them unsuitable for tracks. Untrampled soil bulk density and soil stone content were negatively correlated with the change in bulk density by trampling, and could be used to predict the risk of soil compaction by trampling.

Notes: Abstract. Bypass flow and concurrent leaching of nitrogen were studied on a Vertisol in south-western Kenya under rangeland and bare, manually tilled cropland. Showers of 30 mm/hr were simulated, causing bypass flow of 47–62% in rangeland topsoils and 19–49% in cropland topsoils. Volumetric water contents after experimentation increased from 28 to 35% and from 24 to 38%, respectively, for the two land-use types.In rangeland samples up to 3.4 kg N/ha was found in the leachate of unfertilized soil. With a fertilizer application of 50 kg N/ha, up to 5.7 kg N/ha was lost from a pre-wetted soil, and more than 20 kg N/ha from dry soil. In cropland topsoils up to 2.2 kg N/ha was lost from unfertilized soil, and only up to 2.9 kg N/ha from both dry and prewetted fertilized soil. Although Vertisols are often linked with excess water, the phenomenon of bypass flow can cause water stress to crops in their early growth stages. Nitrogen leaching losses were large from dry grassland, but prewetting helped to decrease them. On intensively cultivated cropland there was little nitrogen leaching; the tilled topsoil was able to retain most of the supplied nitrogen.

Notes: Abstract. Results from over seven years of monitoring of erosion rates on bare arable loamy sand soils at the Hilton experimental site, Shropshire, UK, are reported. On bare plots, rates are very variable; erosion during one summer convectional storm exceeded that recorded during six individual years of plot measurement. Exposure of erodible arable soils to convectional storms puts them at risk of excessive erosion. Plot erosion rates were frequently high, with rates up to 67.4 t/ha occurring during an individual storm. Rates were influenced by rainfall erosivity, slope steepness and soil organic content. Mean soil organic content on the bare plots decreased over five years by 0.08%/yr.

Notes: Abstract. The quantitative effects of different cultivation practices and wheelings on the generation of runoff and soil loss on the South Downs were assessed experimentally with a small drip-type rainfall simulator and rainfall intensities of 42.5 and 23.3 mm/h. Runoff volumes generated by different cultivation practices and between wheeled and non-wheeled areas were significantly different. Amounts of soil lost from different cultivation treatments and from wheelings were less consistent. Less runoff and erosion occurred from shallow cultivated land than from conventionally ploughed and cultivated land. Runoff is further increased by rolling ploughed land after drilling and along tramlines compressed by wheelings. Under high intensity rainfall, considerable runoff can be generated from stubble, especially from wheeled areas.

Notes: Abstract. Soil erosion occurs with sufficient frequency and severity on arable land in the UK to warrant erosion control measures. The main justification is to decrease the off-farm damages resulting from sedimentation and pollution. The grassing of valley floors, the creation of riparian buffer zones and the use of winter cover crops are recommended as suitable measures. These have additional benefits in terms of wildlife habitats and decrease of nitrate leaching. Financial incentives targeted at farmers in erosion-sensitive areas are proposed as the main method of implementation.

Notes: Abstract. This paper describes the application of prototype Canadian land evaluation systems to selected issues. Two categories of applications are recognized. Routine evaluations employ standardized data sets and provide a backdrop for framing broader land-related concerns (e.g. assessments of land supply and suitability). Iterative analyses investigate implications of modified conditions (e.g. soil erosion, global climatic warming, altered food demands) on land use and production options, and require additional data and expertise. The paper demonstrates the capacity of land evaluation systems to address a wide range of issues, and illustrates the range of skills required to maintain and apply these systems.

Notes: Abstract. Uniform application rates of fertilizers and herbicides may result in over-treating some soils and under-treating others; costs may be unnecessarily large and soil, ground water and surface waters may be contaminated. An alternative is site specific treatment, tailored to individual soil types present in agricultural fields of any size. To study the pollution hazards of the herbicide alachlor, leaching and adsorption experiments used disturbed samples and undisturbed soil columns. Adjoining Ves, Normania and Webster soil series (Udic Haplustoll; Aquic Haplustoll; Typic Haplaquoll) were sampled and analysed for various properties. Ring uniformly 14C-labelled alachlor was used to study adsorption and leaching characteristics in these soils. Results show different alachlor behaviour in topsoil and subsoil layers.

Notes: Book review in this ArticleErosion, Transport and Deposition Processes Edited by D.E. Walling, A. Yair and S. Berkowicz.Statistical Methods in Soil and Land Resource Survey. By R. Webster and M.A. Oliver.

Notes: Abstract. Water erosion was recorded between mid-October and mid-December 1989 in 31 out of 73 erosion-susceptible arable fields being monitored in England and Wales. Most fields were drilled to winter cereals. Tramlines and wheelings were the factors most commonly linked with initiation of erosion, particularly where runoff was concentrated on valley floors or headlands. Lack of crop cover (〈 15%) was also an important factor at a number of sites; 25–30% ground cover was generally sufficient to protect the soils from erosion. Erosion was initiated by rainfall events of 15 mm or more in a 24 h period, with a maximum intensity greater than 4 mm/h. A large erosion event in south-west England was associated with 33 mm of rainfall in 4.25 h, with a maximum intensity of 22 mm/h.

Notes: Abstract. When sewage sludge is surface-applied to grassland, herbage may become contaminated with heavy metals from adhering solids, posing a risk to the health of grazing livestock and possibly increasing the entry of heavy metals into food products. A field trial examined factors influencing sludge adhesion to leaf surfaces and changes in the concentration of heavy metals in herbage over time. Metals differed in their persistence on leaves. The time required for metal concentrations in herbage to reach background levels depended on herbage growth, the dry solid content of sludges, their rate of application and the height of the grass when the sludge was applied. The implications of the results for the length of a safe no-grazing period following sludge application are discussed in the context of UK and EC legislation governing sludge use on agricultural land.

Notes: Abstract. The production of pigs in outdoor units is gaining in popularity in the United Kingdom and is often concentrated on free-draining soils over important aquifers. Originally, stocking rates were sufficiently low to ensure the maintenance of a grass crop, but recently they have increased. Pigs are natural ‘rooters’ and wallowers and so cause damage to vegetation and soil structure. With overstocking these natural activities lead to considerable areas of bare, uncropped ground for much of the year. This paper assesses the potential for leaching of nitrate from such land, and makes recommendations for decreasing it.

Notes: Abstract. A computer-based land evaluation information system (MicroLEIS) was developed for optimal use of agricultural and forestry land systems under Mediterranean conditions. Through an interactive procedure several land capability, suitability and yield prediction methods may be applied. The system addresses land evaluation at reconnaissance, semi-detailed and detailed scales in an interrelated manner. Biophysical land evaluation methods are incorporated using empirical, scale-appropriate models, which range from purely qualitative (reconnaissance) through semi-quantitative (semi-detailed) to quantitative (detailed). This software is helpful for teaching, research and development, predicting appropriate agroforestry land uses. Its use is illustrated by an example.MicroLEIS runs on IBM PC, XT, AT, or a compatible microcomputer with at least 128 kilobytes of RAM and a PC-DOS or MS-DOS version 2.0 or later operating system. The software package on double or high density diskettes can be obtained from the first author.

Notes: Book review in this ArticleThe Soil By B. Davies, N. Walker, D. Ball & A. Fitter.Soils in the Urban Environment Edited by P. Bullock & P.J. Gregory.Soil Management for Sustainability Edited by R. Lai & FJ. Pierce.Development of K-Fertilizer Recommendations Proceedings of the 22nd Colloquium of the International Potash Institute held at Soligorsk, USSR, 1990.Soil Micromorphology: a Basic and Applied Science Edited by L.A. Douglas, 1990.

Notes: Abstract. Results of the Representative Soil Sampling Scheme between 1978 and 1988 show that soil acidity remains widespread, particularly in Wales, and suggest that the proportions of grassland with low pH increased during this period in the traditional grassland areas of England and Wales.Average soil nutrient levels changed little over the decade. However, at least one in five grassland fields are likely to suffer yield restrictions because of shortage of soil P or K (index 0). One in four arable fields were found to be at index 1 for K, indicating that many crops are being grown at potassium levels which can be described as borderline. On the other hand, 22% of arable crops were grown at phosphate index levels in excess of 3, so phosphate savings could be made on many crops. Texture and calcium carbonate levels and their relationships with nutrient levels are also examined.

Notes: Abstract. The influence of intensively fertilized short-rotation forest plantations on nitrogen concentrations in groundwater was studied by piezometer readings and water sampling over a two-year period in a sandy field growing willow (Salix spp.) and other species. The mineral-N content of the unsaturated zone was measured in soil samples collected to 0.9 m depth. Although piezometer readings suggested that deep groundwater could be affected, the concentrations of nitrate-N and ammonium-N were usually less than 1 mg per litre. There was also little mineral-N in the unsaturated zone, except for occasional peaks in the topsoil (0–30 cm) after application of fertilizer. We conclude that there is little risk of nitrogen contamination of groundwater in intensively cultured tree stands receiving up to 150 kg N/ha/yr as fertilizer. This is probably because willow can take up water and nitrogen from deep parts of the soil profile.

Notes: Abstract. Seasonal variation in the aggregate stability of chalk downland soils on the South Downs, East Sussex, UK, was studied using two measures of aggregate stability: water stable aggregation by wet sieving and dispersibility by a turbidimetric determination. Aggregate stability and organic carbon content were assessed on a monthly basis at 20 sites over a 19-month period.Results indicated considerable variation in water stable aggregation over the time period studied but little variation in dispersibility. There were differences between sites mainly reflecting differences in organic carbon content. Soils with more organic carbon showed less seasonal variation in aggregate stability than soils with small amounts of organic carbon. This suggests that in less organic soils organic materials, mainly microbial in origin, play an important role in forming stable aggregates, though their effect is transient.

Notes: Abstract. The water contents of a restored and an undisturbed soil were monitored over two ‘dry’ growing seasons in order to examine the differences in crop water availability from different horizons. Bulk density was approximately 10% greater in the topsoil of restored land than in undisturbed land, and the water holding capacity was less, probably because there was less organic matter. In the subsoil a major problem was the inability of the soil to allow winter rainfall to recharge the water reserves. Bulk density and penetration resistance were greater in the restored subsoil than in the undisturbed subsoil. Increases in penetration resistance on drying may have restricted rooting activity, especially in the restored subsoil.Ripping of the subsoil to a depth greater than the usual 0.5 m, possibly early in the year in a grass crop to allow new root growth to exploit the cracks, may increase water availability for future dry seasons.

Notes: Abstract. Changes in chemical and physical properties and erodibility of a vertisol were studied in relation to land use. The vertisol, which occurs extensively in the semi-arid south-east of Zimbabwe, is derived from basalt and has a self mulching surface layer. Irrigated crops show static yields despite introduction of improved varieties. Four uncultivated sites were selected as controls and compared with five irrigated and four dryland sites. Surface soils were analysed for a range of chemical and physical properties, and laboratory rainfall simulation was used to measure soil erodibility under high intensity rain. The irrigated soils had greater exchangeable sodium and available phosphorus than the uncultivated soils. In contrast, dryland soils showed no such changes apart from a decrease in the amount of small water-stable aggregates. The soils are very erodible under high intensity rain but no significant differences were found between sites. We conclude that, although soil chemical changes have taken place in the irrigated soils, significant soil degradation has not occurred at the sites examined. The static yields probably result from management problems. However, immediate measures should be taken to improve drainage and irrigation management in the irrigated soils to avoid further sodium increases.

Notes: Book review in this ArticleFarming, Fertilizers and the Nitrate Problem By T.M. Addiscott, A.P. Whitmore and D.S. Powlson.Land Husbandry By N. Hudson.

Notes: Abstract. To assess the effect of different land uses on soil properties, five land use types (fallow, Gmelina, arable, secondary forest and cocoa plots) on a sandy loam Alfisol (Typic Kandiudalf) were compared in terms of surface (0–15 cm) soil pH, exchangeable acidity, K, Ca and Mg, extractable P, total N, organic matter, gravimetric moisture, temperature and bulk density. There were significant differences (P≤ 0.05-P≤ 0.001) between the land use types for all the properties except exchangeable acidity and moisture. All the land use types differed significantly from each other in at least four properties. Fallow and secondary forest differed in nine properties, fallow and cocoa in seven and fallow and Gmelina in six. In terms of the number of properties with high variability (CV ≥ 35%), the order was arable, secondary forest and cocoa (4) 〉 Gmelina (3) 〉 fallow (1).

Notes: Abstract. The suitability of the University of Zambia farm for selected crops was assessed using the principles and concepts of the FAO Framework for Land Evaluation. Moisture and nutrient availability were found to be the most limiting land qualities, but moisture availability is a more important consideration because the farm is managed with high inputs. Heavy dependence on rainfall makes the farm very vulnerable to drought which has had a devastating impact on yields in recent years.Soyabean, potato and wheat are the best-suited crops. Sunflower is not recommended because of the low market value. Maize is not a suitable crop because of its sensitivity to water stress and nutrient availability. Rhodes grass is recommended in mapping units where other crops have little economic value.The FAO Framework for Land Evaluation can be used in Zambia. It can identify land utilization types that are physically and economically suitable. Based on these findings an appropriate land use plan of the University Farm has been developed and implemented.

Notes: Book review in this ArticleAcid Soil and Acid Rain (2nd edition) By I.R. Kennedy.Proposals for the Classification, Description and Mapping of Soils in Urban Areas By J.M. Hollis (Soil Survey and Land Research Centre).

Notes: Abstract. Two experiments on the same site in different years compared the effects of different intensities of deep loosening on soil properties and crop yield. Both experiments included subsoiling and one experiment, with potatoes, also included double digging and a comparison of conventional and zero traffic. The site was in a moist climate area (S.E. Scotland) on an imperfectly drained Gleysol with a clay loam subsoil. Cone resistance, soil water content and potential, bulk density and crop yield were measured to assess the effects of the treatments. Subsoiling did not loosen the soil very effectively because the subsoil was wetter than the plastic limit at the time of cultivation, even though the growing season prior to subsoiling was drier than average in both years. Double digging was more effective than subsoiling. Zero traffic gave a large yield benefit, especially when combined with double digging. There was no crop response to deep loosening in the presence of conventional traffic. Deep loosening had little effect on the drainage status of the topsoil.

Notes: Abstract. Qualitative and quantitative physical land evaluations differ in their technical procedures, i.e. use of expert knowledge versus process-orientated simulation models. This paper compares the results of both procedures using the growth potential for sugar-beet in the European Community. Qualitative procedures give suitability expressions, such as land being well suited or moderately suited for a given land use. Less than 30% of EC land was found to be well suited or moderately suited under water-limited conditions. No quantitative expressions for the crop yield potential are, however, produced. The quantitative procedure describes suitability in terms of average crop yield and its temporal variability. Water-limited and potential dry matter yields of sugar-beet were estimated to range from 3.5 to 20 t/ha, and from 6 to 25 t/ha, respectively.Comparison of results of the qualitative and quantitative procedures for regions showed that the suitability classes obtained by the former can be characterized by different yield distributions derived from the latter. These yield assessments showed that results of qualitative land evaluation procedures aimed at assessing yield potential are meaningful only when they are linked to agroclimatic zones. The comparison also showed that some moderate restrictions, which often can be counteracted by adequate farm management, are not incorporated into the quantitative procedure.

Notes: Abstract. The soil water regime was monitored at a forested experimental site in Cumbria, UK. Over an 83-week period following the clearfelling of 35-year-old Sitka spruce, soil water level measurements were related to total weekly rainfall in drainage treatment plots (10, 20 and 40 m ditch spacing) in three replicate blocks. Analysis showed a block × treatment interaction which might be related to soil differences between blocks. Significantly deeper soil water levels were measured in the most intensively drained plots of the two gently sloping blocks on a peaty gley soil. Drainage intensity had no effect on soil water level in the third block situated on a surface-water gley soil on a steep slope.

Notes: Abstract. The accuracy of assays based on galactosidase and the enzyme-linked immunosorbent assay specific to Thanatephorus cucumeris were compared with techniques based on soil dilution plating and baiting in sterilized field soil. Although soil dilution plating is reasonably quantitative, it requires substantial time, material and labour. Plant baits gave inconsistent results in the estimation of T. cucumeris populations in the soil. Enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies is suitable for detecting the presence of a range of anastomosis groups (AGs) of 71 cucumeris in soil samples, but more quantitative applications seem to be limited to a very narrow range of concentrations of the fungus (0–10 μg/g). Monoclonal antibody ELISA could be used if the soil samples are routinely further diluted, provided the range of concentrations is uniformly low. An assay of β-galactosidase permits estimation of a more adequate range of concentrations (0–500 μg/g) and may be used in defined experiments using uninoculated soil samples.

Notes: Abstract. The tolerance of wheat plants to manganese is shown to depend on the magnesium concentration in shoot tissue, such that growth is a function of the ratio of the two ions Mg: Mn. This ratio in the plant (Rp) and in the soil solution (Rs) was related by the equation:ln Rp= 1.45+0.31 ln Rs.Values of Rp not limiting to growth need to be determined for different crops, but we conclude that corresponding values of Rs can be predicted using solution culture trials. They can then be used to identify remedial treatments in soils where manganese toxicity occurs. In the Eutric Cambisol examined, small amounts of calcium carbonate decreased manganese concentrations in the soil solution such that amounts of magnesium which could easily be applied to a field gave appropriate values of Rs for wheat.

Notes: Two cultivars of white clover (Ladino and Kent Wild White) and two cultivars of lotus (Grasslands Maku and G4703) were grown in pots of soil at low to moderate levels of phosphorus (P) supply. Nitrogen supply was by fixation. Cell size and nitrogen, phosphorus and chlorophyll content per cell were estimated from samples of leaf tissue. Maku lotus had larger cells and higher cellular contents of metabolites than the clovers. These measurements support earlier suggestions that, compared with white clover, the higher P-efficiency (dry matter per unit of internal P) of Maku lotus may be explained by cytological factors without recourse to explanations based on differences in nutrient metabolism. The relatively large cells and high metabolite levels per cell of Maku lotus appear to arise from its creation as an artificial tetraploid.

Notes: Herbage allowance is one of the important pasture factors in the determination of intake by grazing livestock. Ingestive behaviour of 12 adult Angus cows (Bos taurus) was measured over a range of allowances (0·25 to 0·72 kg dry matter (DM) per 100 kg live weight (LW) for a 1-h period) of vegetative tall fescue (Festuca arundinacea Schreb.). A balanced change-over design was used to estimate direct, residual and permanent effects of herbage allowance on rate of DM intake, rate of biting and herbage DM intake per bite. In Experiment 1, herbage DM intake per meal increased linearly from 0·68 to 1·72 kg (100 kg LW)−1 as DM allowance increased from 0·25 to 0·72 kg (100 kg LW)−1 h−1. Cows grazed at ·30 kg (100 kg LW)−1 h−1 and stopped grazing when the sward was reduced to a height about 10 to 12 cm above the soil surface, approximately defined by the tops of pseudostems. In Experiment 2, herbage DM intake rates of 0·29, 0·47 and 0·42 kg (100 kg LW)−1 h−1 were recorded as cows grazed allowances of 0·43, 0·70 and 0·90 kg (100 kg LW)−1 h−1 for most of the 1-h grazing period. Limiting herbage DM allowances in Experiment 2 were associated with small reductions in rate of biting and herbage DM intake per bite as allowance declined. Sward DM density (〉5 cm) was an important variable in the determination of herbage DM intake rates at lower herbage allowances.

Notes: Two experiments were carried out to examine the interaction between early and late-heading varieties of ryegrass and date of harvesting of primary growths for silage in terms of the performance of beef cattle. A sward containing equal proportions of three early heading varieties (Cropper, Premo and Frances) (50% ear-emergence on 18 May) was harvested on 20 May (T1), 28/29 May (T2) and 5/6 June (T3) and a sward containing three late-heading varieties (Perma, Preference and Parcour) (50% ear-emergence on 12 June) was harvested on 28/29 May (T4), 5/6 June (T5) and 12/14 June (T6) in 1985 and 1987. In each year the six silages were harvested without wilting and were ensiled in trench silos. In Experiment 1 they were offered ad libitum and unsupplemented to 48 steers (407 kg live weight (LW)) for 101 days and in Experiment 2 they were offered with 2 kg concentrates per head daily to 48 heifers (392 kg LW) for 105 days. In Experiment 1 in vivo digestible organic matter (DOMD) concentrations in dry matter were 717, 671, 643, 709, 672 and 640 (s.e. 8·4) g (kg DM)−1; silage DM intakes 7·1, 6·6, 6·6, 7·2, 7·3 and 6·7 (s.e. 0·15) kg d−1; LW gains 0·94, 0·74, 0·62, 0·90, 0·82 and 0·57 (s.e. 0·047) kg d−1; for T1 to T6 respectively. For Experiment 2, DOMD concentrations were 732, 699, 636, 734, 686 and 663 (s.e. 9·6) g (kg DM)−1; silage DM intakes 6·4, 5·7, 6·0, 6·0, 5·5 and 5·0 (s.e. 0·22) kg d−1; LW gains 1·12, 0·92, 0·99, 1·14, 0·88 and 0·76 (s.e. 0·078) kg d d−1; and carcass gains 0·66, 0·56, 0·51, 0·68, 0·55 and 0·48 (s.e. 0·048) kg d d−1; for TI to T6. It is concluded that silages made from early and late-maturing swards of perennial ryegrass sustained similar levels of performance in beef cattle when they were harvested at equal digestibility, and the digestibility declined at similar rates for the two sward types when harvesting of the primary growths was delayed. Under the conditions of these experiments the same level of animal performance was sustained by silages made from the two swards when the late-maturing varieties were harvested 7 days after the early varieties. This compares with an interval of 25 days between the early and late-maturing varieties reaching 50% ear-emergence.

Notes: In a small-plot experiment at Hurley, UK, infection of perennial ryegrass with the endophytic fungus Acremonium lolii had no apparent effect on seedling populations and herbage yield of ryegrass and white clover sown in mixture. The plots were maintained under two levels of irrigation with or without pesticide (carbosulfan granules) to study possible interactions with stress due to drought or pest damage. The higher level of irrigation consistently increased yield of both grass and clover during 1989 and 1990, but the effects of endophyte and pesticide on yield were not consistent, nor were the few significant interactions between factors. It is concluded that infection of ryegrass does not appear to increase ryegrass production or to decrease white clover production in the UK, in contrast to reports from New Zealand.

Notes: A long-term field grazing experiment was begun in 1982 to examine the impact of efficient field drainage on herbage and animal production from swards on an impermeable clay loam in the south-west of England. Drained and undrained lysimeter plots (each of 1 ha) were established on the existing permanent sward and received annual applications of fertilizer N of 200 or 400 kg ha−1. Similar plots were initially ploughed and reseeded with Lolium perenne (cv. Melle), and received fertilizer N at an annual rate of 400 kg ha−1. All plots were continuously stocked by beef cattle and stock numbers were adjusted to maintain a constant sward height and to avoid poaching damage. Results for the first 5 years show that the benefits from drainage were modest and, for beef production, unlikely to pay for its costs over the shorter term. The main benefit was in spring when herbage dry matter yield was 11% greater on the drained plots, but with no significant interaction with fertilizer N level or sward type. This benefit was reduced to 3% on an annual basis, due to the effect of the larger soil water deficits sustained by the drained swards in mid-season. Drainage increased the annual liveweight gain per ha by the grazing cattle by 11%. Possible mechanisms accounting for these effects are discussed in relation to the influences of seasonal patterns of weather.

Notes: The effects of the time of access to feed (8 h or 24 h) with silage-based rations (unwilted or wilted silage) were studied for two years. In each year the experiment comprised 52 individually fed cows in a 2 × 2 factorial design and covered weeks 1-20 of the lactation. The cows were offered silage ad libitum, 1 kg of hay per day, and concentrate according to the predicted energy-corrected milk (ECM) yield.Increasing the access time from 8 h to 24 h increased the total intake of dry matter (DM) and metabolizable energy (ME) by 6%. This resulted in increased yield of ECM by 5%. The eating rate of forage was significantly increased by restricted time of access. Wilting had no significant effect on total feed intake or milk yield. The importance of providing a sufficient length of time during which the cows have access to feed was confirmed. It was concluded that 8 h d−1 of access to silage-based rations is not enough in early lactation.

Notes: Slugs of three species, Deroceras reticulatum, Arion fasciatus and A. subfuscus, which had fed on sclerotia or apothecia of Sclerotinia trifoliorum, transmitted the disease to water agar plates. In the case of Arion spp., transfer of excreta also produced infection.After feeding on apothecia D. reticulatum transmitted the disease to white clover plants, although the direct transfer of apothecia produced higher levels of infection. The visible symptoms of the disease were reduced when slugs were allowed to remain on the plants, apparently owing to a feeding preference of D. reticulatum for diseased leaf tissue.

Notes: An experiment was conducted over 3 years (1983-85) to assess the performance of Holcus lanatus German Commercial and cv. Massey Basyn compared with Lolium perenne cv. Perma on a gley soil under sheep grazing in the Scottish uplands. All grasses were sown together with Trifolium repens cv. Grasslands Huia. The swards were rotationally grazed at similar herbage allowances. During the first harvest year, the swards were grazed hard to a low mass (500 kg DM ha−1). In the second harvest year, post-grazing herbage masses of 500 and 1000 kg DM ha−1 were compared.Perma ryegrass had a higher level of herbage production than both H. lanatus cultivars in the first and second harvest years after sowing and hence had a greater number of sheep grazing days. The ryegrass sward consisted of 25% more green sown grass (85 cf. 60%) but 12% less white clover (4 cf. 16%) compared with both H. lanatus cultivars in the establishment and first harvest years. The persistence of all three grasses was poor although ryegrass had a higher presence (36%) than either Massey Basyn (22%) or German Commercial (13%) at the end of the. second harvest year.At a similar herbage allowance, there were no significant differences in the herbage intake and liveweight gain of sheep. Ryegrass had a higher organic matter digestibility and lower neutral and acid detergent fibre and lignin contents than either of the H. lanatus cultivars.In the second harvest year, although herbage production was greater at the higher herbage mass, there was no difference in the proportion of sown grass.It was concluded that ryegrass is a superior grass to H. lanatus on upland soils with high N status, moderate P status and a high pH.

Notes: A comparison was made of canopy structure, photosynthesis and dry weight production, during growth periods in spring and summer, of a large-leaved and a small-leaved cultivar of white clover (Blanca and S184), grown in mixtures with perennial ryegrass or tall fescue. Both clovers had leaves in the topmost, best-lit layer of the canopies, even when sward surface height reached 40 cm in early June. Except early in the spring growth period, both clovers had a greater proportion of their leaf area near the top of the canopy than did their companion grass. Both clovers had a greater relative growth rate than the grass, increasing their percentage of the total crop dry weight during both spring and summer growth periods. Differences between clover cultivars were relatively minor and did not affect their dry weight in either measurement period. During the first growth period there was more clover dry weight with tall fescue than with ryegrass. There were no effects of clover cultivar on grass dry weights.

Notes: Soil samples taken from one- to four-year-old swards of white clover and perennial ryegrass at 34 sites, and from older clover/grass swards at 56 sites in England and Wales, were examined for plant parasitic nematodes. Stolons of white clover from 46 of these sites were examined for nematodes. Clover cyst nematode (Heterodera trifolii) and white clover stem nematode (Ditylenchus dipsaci) were found in 62% and 41% of sites respectively. The grass cyst nematode (Punctodera punctata) was present in 56% of 71 sites examined, and other grass cyst nematodes (H. bifenestra and species of the H. avenae group) occurred in 13% and 17% of sites. Two root-knot nematodes were found, Meloidogyne naasi and M. hapla, in 15% and 4% of the samples examined. Migratory nematodes were extracted from 63 samples, and spiral, pin and lesion nematodes were found in more than 90%. Stunt nematodes were less frequent (65%) and criconematids (19%) were found relatively infrequently. The significance of these observations to grassland productivity is discussed.

Notes: Plants were grown in pots outdoors and placed in four growth chambers at different temperatures (day temperatures 9, 13, 17 and 21°C) and at three different phenological stages. They were then harvested at weekly intervals for up to 6 weeks. Pots left outdoors were harvested at the same time.Digestibility was nearly constant during the 6 weeks at the lowest temperature. The rate of decline in digestibility per day, calculated from that portion of the data which was assumed to be best for such estimation, was 0·060±0·008 per cent units for each degree increase in temperature.The results indicate that the temperature effect on decline in digestibility is the same for early as for late growth stages.

Notes: Three grass silages were made from perennial ryegrass ensiled without additive application (U) or with the application of formic acid (F) or an enzyme mixture of hemicellulases and cellulases (E).Analysis of silages showed that both untreated and enzyme-treated silages had higher lactic acid concentrations than formic acid-treated silage. Enzyme-treated silage had lower levels of ADF and NDF but higher concentrations of residual WSC than other silages.The silages were fed to growing steers supplemented with either rapeseed meal (RSM) (60 g kg−1 silage DM) or fishmeal (FM) at a level isonitrogenous with RSM diets, so providing six diets (UR, UF, ER, EF, FR, FF). Organic matter intakes were similar, but ADF intakes were significantly (P 〈 0·001) lower with enzyme-treated silage diets (UR, 1163; UF, 1160; ER, 1104; EF, 1035; FR, 1216; FF, 1213), as were intakes of NDF (P 〈 0·01) (UR, 1946; UF, 1955; ER, 1877; 1772; FR, 2031; FF, 2041). Apparent whole tract digestibilities of organic matter were significantly (P 〈 0·001) higher with enzyme-treated silages (UR, 0·644, UF, 0·644; ER, 0·668; EF, 0·678; FR, 0·633; FF, 0·633). Liveweight gains were generally higher with treated silage diets and RSM supported a greater response than FM (UR, 0·496; UF, 0·498; ER, 0·567; EF, 0·489; FR, 0·543; FF, 0·506) with both enzyme and formic acid-treated silages, although none of these differences were significant.

Notes: The role of the legume in the nitrogen (N) cycle was examined in grazed pastures receiving no N fertilizer of both temperate and tropical regions by simulating the fluxes of N through different processes of the cycle. The amounts of legume-fixed N required to balance the cycle without invoking a drain on soil organic N reserves (i.e. no net N mineralization) was estimated to vary from 38 to 53% of the above-ground herbage N or from 20 to 31% on a dry matter (DM) basis for tropical pasture systems with a range of pasture utilization of 10–40%. At higher pasture utilization levels of 50-70%, more typical of intensively grazed temperate pastures, the N input requirement in the absence of fertilizer N would be 57-67% of the aboveground herbage N or 35-45% DM. An examination of the role of each contributory process of recycling (viz. excreta returns, internal cycling or remobilization from senescing tissues, litter decomposition) suggests that variations in the amounts of internally cycled N would have the greatest impact on the requirement for biologically fixed N at low levels of pasture utilization (10-40%), while at high pasture utilization levels of 70%, variations in the recovery of excreta-N would have a major effect on the requirement for fixed-N to balance the cycle.The amounts of biologically fixed N required to sustain a range of herbage DM yields of 3-22 t DM ha −1 yr−1 would range from 15 to 158 kg N ha−1 yr−1 for tropical pastures. For intensively managed temperate pastures producing 6-15 t DM ha−1 yr−1 with a N content of 3·5%, a range of fixation of 120-352 kg N ha−1 yr−1 is required. These simulations indicate how legume contents of 20-45% of herbage DM could contribute to productive and sustainable (in terms of N) pasture systems of both temperate and tropical regions

Notes: In a two-year experiment, three silages were prepared from herbage treated either with an inoculant at 1·25 × 105 organisms (g fresh material (FM))−1. formic acid (850 g kg−1) at 4 1 (t FM)−1, or no additive (untreated). In Experiment 1, unwilted and in Experiment 2, wilted silages were investigated and had mean dry matter (DM) and water soluble carbohydrate (WSC) concentrations at ensiling of 171 g kg−1 and 17·6 g (kg FM)−1 and 263 g kg−1 and 25·1 g (kg FM)−1, respectively. In Experiment 1, 45 and in Experiment 2, 54 individually fed cows were used to evaluate the silages in three-treatment, randomized-block design experiments. During weeks 4-12 of lactation the cows were offered silages ad libitum and during weeks 15-26 a constant amount of silage was fed. There were few major differences in chemical composition of the resulting silages. Formic acid had no effect on silage digestibility. Inoculant treatment increased digestibility when the grass had been wilted. The use of formic acid resulted in increased silage DM intake of 9% during weeks 4-12 of lactation in Experiment 1 but not in Experiment 2. The inoculant gave no increase in silage DM intake over the control in Experiment 1 but increased silage DM intake by 7% in Experiment 2. There was no significant response in milk yield to formic acid. In Experiment 2 the response in milk yield to inoculant treatment was significant both in weeks 4-12 of lactation (4%) and in weeks 15-26 of lactation (5%). It is concluded that the response in milk yield to the use of a specific inoculant appears to be mediated through increased intake of metabolizable energy (ME).

Notes: Two field trials were carried out in successive years in which (1) perennial ryegrass and white clover seeds were drilled together, or (2) clover was broadcast and grass drilled, or (3) both clover and grass were broadcast. The last two treatments were followed by harrowing or not of the seed bed. Sowing took place in early May or August. Four harvests were taken in each full harvest year.In establishment years, sowing in May resulted in a total dry matter (DM) production at least ten times higher than that resulting from sowing in August. No sowing method treatment effects on total DM or clover yield were significant in the establishment year (measured only in spring-sown plots). In the first harvest year the August-sown treatments produced 15% less DM than those sown in May and clover yield was, on average, 40% lower than the earlier sown treatments; clover proportion followed a similar pattern to yield.Drilling of both grass and clover without harrowing produced swards with a significantly lower proportion of clover in the first harvest year in the first trial than in treatments in which clover was broadcast but not harrowed. In the second trial at harvest 1, clover proportion just failed to be significantly lower in the treatment in which grass and clover were drilled than in the treatment when clover was broadcast and the seed bed harrowed.In the second harvest year (first trial only), annual clover yield and proportion were not affected but drilled grass and clover had lower DM yield than when grass was drilled and clover broadcast without harrowing and when both were broadcast, without harrowing. At one harvest, the yield of clover in treatments sown in May was actually lower than that in the later-sown plots.In a subsidiary controlled environment experiment to investigate the effect of stage of clover development on cold hardiness (a factor in autumn-sown swards), plants which were about to initiate stolons (58 days old) had an LD50 of −5·1° compared with −9·3°C for plants 60 days older.It is concluded that autumn sowing delays the time at which optimum clover production is achieved (late in the first full harvest year) and method of sowing does not compensate for this. However, sowing in August under Northern Ireland conditions does not seem to jeopardize the chances of a successful establishment of white clover, and plants should be sufficiently winter hardy to withstand relatively hard freezing conditions.

Notes: Three experiments have been conducted to study the effect of virginiamycin in young grazing-bulls (Experiment 1) and heifers (Experiments 2 and 3). Rotational grazing on permanent grassland was practised and animals were supplemented with 1 kg dried sugarbeet pulp per head daily. Control groups did not receive virginiamycin via the supplement, while it was incorporated at 120, 300 and 200 mg kg−1 for the treatment groups in Experiments 1 to 3 respectively.Average daily liveweight gain was significantly increased from 0·59 to 0·72 kg in Experiment 1 and from 0·73 to 0·81 kg in Experiment 3, but was not affected in Experiment 2 (0·51 vs 0·55 kg). Virginiamycin also increased liveweight gain per ha by 12, 7 and 13%, respectively, for the three experiments. Grazed area per animal was not enlarged to the same extent as the calculated daily energy allowances, which may suggest an improved digestibility and/or rumen fermentation.

Notes: The productivity of 20 cultivars from a range of 13 grass species was compared by harvesting four times during each of three successive growing seasons. In the experiment, 120 kg N ha−1, 42 kg P2O5 ha−1 and 42 kg K2O ha−1 were applied annually.Mean annual yield was 3229 kg DM ha−1 and 2147 kg DOM ha−1. Cultivars were arranged in seven groups for comparison. Three of the groups, Lolium, Phleum and ‘others’ (the latter consisted of Festuca arundinacea cv. Dovey and Poa pratensis cv. Bensun A.34) appeared significantly lower yielding than the Dactylis, Festuca (fine-leaved), Agrostis and Holcus groups.In the Lolium group, cv. Gremie outyielded cv. Melle every year. No cultivar of Dactylis was significantly better than any other in its group. Phleum CVS Motim and Eskimo were similar and superior to cv. S.50. Festuca ovina cv. Novina and Agrostis canina cv. Kingstown were marginally the best in their respective groups. The two cultivars of Holcus performed virtually identically. Festuca arundinacea cv. Dovey was a good producer of early spring grass. Poa pratensis cv. Bensun A.34 was generally low yielding and subject to fungal rust attack in autumn. The pattern of seasonal DM production was 16% in early spring (cut in October/November), 39% in mid-season (cut in December), 40% in late summer (cut in February/March) and 5% in autumn (cut in April/May). Quality of the herbage was superior to the main indigenous grass Cortaderia pilosa.It was concluded that although the experiment was conducted under a cutting regime it provided useful guidance for seeds mixture formulation and stock carrying capacity calculations.

Notes: Two silages were made from primary growth perennial ryegrass and ensiled after the application of either formic acid or an enzyme mixture of cellulase and hemicellulase. Silage analysis showed both silages to be well preserved with low pH of 3·70 and 3·62 for the formic and enzyme treatments respectively. Formic acid-treated silage had a higher total amino acid concentration than enzyme-treated silage. The silages were offered to growing steers either as the sole diet or supplemented with rapeseed meal at 60 g or 120 g fresh weight kg−1 silage DM offered, in a 6 × 6 Latin square arrangement.Non-ammonia nitrogen and microbial nitrogen flows at the duodenum (g d−1) were significantly (P 〈 0·05) increased by supplementation of enzyme-treated silage compared with formic acid-treated silage (enzyme, 83·6, 58·7; enzyme + 60 g, 101·7, 75·3; enzyme + 120 g, 112·5, 80·7; formic, 91·9, 63·7; formic + 60g, 88·3, 67·9; formic + 120 g, 95·5, 67·1) respectively. Efficiencies of microbial protein synthesis were increased for supplemented enzyme-treated silage diets and values were reduced for supplemented formic acid-treated silage diets compared with the silage only diets (enzyme, 27·9; enzyme + 60 37·7; enzyme + 120 g, 38·6; formic, 33·7; formic + 60g, 31·2; formic + 120 g, 28·8). Total amino acid flow at the duodenum increased with supplementation of both silages; however, microbial amino acid flow increased significantly (P 〈 0·05) with supplementation of enzyme-treated silage compared with formic acid-treated silage diets. Significantly greater amounts of cystine, methionine, alanine, valine and aspartic acid entered the small intestines of animals receiving supplemented enzyme silages compared with supplemented formic acid silages.

Notes: Laboratory experimentation found smooth and pubescent leaf surfaces to behave as specular (mirror-like) reflectors of ultrasound, whilst ribbed leaves behaved as an array of reflectors. It was concluded that swards composed of species with smooth, erectophile leaves would reflect ultrasound poorly and that this may explain the low sward height measurements returned by the sonic sward stick in the field when compared with the HFRO sward stick. The likely effect of species with planophile leaves such as clover is discussed. The sward surface influencing a sonic sward stick measurement was calculated to subtend a solid angle of about 43° at the transducer, equivalent to an area of about 1000 cm2 with the transducer mounted at a height of 50 cm. However, measurements made over turves of varying sizes or over turves with cores of varying size removed found the sensitivity decreased very rapidly beyond an inner area subtending a solid angle of about 7° this is equivalent to an area of about 30 cm2.

Notes: The mechanisms that terminate meals of cattle grazing lucerne (Medicago sativa L.) are not well defined. Sub-acute bloat may lead to cessation of grazing and, consequently, surface active substances used in the treatment and prevention of bloat, such as poloxalene, may extend grazing meals and increase herbage intake. Twelve mature Angus cows (Bos taurus) were offered 0, 12·5 and 25·0 g poloxalene in 0·5 kg of crushed maize (Zea mays L.) kernels each day, immediately before two consecutive 1-h measured parts of a grazing meal on 21- to 24-day-old lucerne swards with a herbage dry matter (DM) mass (〉 5 cm) of 2·03 t ha−1 and herbage DM mass allowance of 3·55 kg hd−1h−1. Total herbage DM intake was 2·52 kg hd−1 during the first hour and 1·54 kg hd−1 during the second hour of the 2-h grazing meal. Differences in herbage intake were attributable to a cessation of grazing. Mean rates of biting were 26·3 and 14·8 bites min−1 and mean DM intakes per bite were 1·82 and 4·38 g during the first and second part of meals, respectively. Poloxalene treatments caused a small linear decline in grazing time during the first part of meals and a larger increase in grazing time during the second part of meals. Lower rates of DM intake caused by poloxalene were offset by increases in grazing time. It was concluded that poloxalene moderated ingestive behaviour within grazing meals of immature lucerne and this response may have been at least partly due to the relief of sub-acute bloat.

Notes: Two experiments (1a and 1b) were carried out to examine the effects of differences in pre-grazing herbage mass and composition on milk production by cows grazing in early spring. Swards with high (5 · 1t DM ha−1) or low (2 · 9 t DM ha-1) pre-grazing masses in early spring were created by either long or short periods of regrowth during the preceding winter.The low-mass swards contained lower concentrations of grass stem and senescent material, but higher concentrations of clover, than the high-mass swards. Herbage from the low-mass swards was also more digestible.Cows were offered common daily herbage allowances from both swards (26 and 22 kg DM cow−1 in Experiments la and lb respectively). The cows grazing on the low-mass swards produced significantly greater yields of milk, milk fat and milk protein.The results show that herbage from the lowmass swards was of higher feeding value for lactating cows in early lactation. The practical implications for milk production per cow and per hectare are discussed.

Notes: Perennial ryegrass/white clover pastures grazed by sheep and receiving either no fertilizer N (No) or 120 kg N ha−1 year−1 (N0) were maintained with surface heights of 2·5, 3·5 and 5·0 cm for over four years. The treatments were replicated.The white clover (WC) population was greatest in the N0treatment, and declined during the study. Between-year variation in WC was negatively related to rainfall and positively related to temperature, WC as a proportion of the total plant population decreased during the summer in the Nl treatment. The perennial ryegrass (PRG) population was greater in the Nl treatment, declined during the study and both within and between years was positively related to temperature. The population density of the unsown grasses was highest in the N-fertilized treatment and in the swards maintained at the lowest heights (these treatments also had the highest stocking rate); it increased during the study, within-years being positively related to temperature and between-years being positively related to rainfall.The WC stolon extension rate was largely unaffected by N fertilizer application and was greatest in the taller swards. Leaf appearance rate was unaffected by N fertilizer application and sward height; it was positively related to temperature and negatively related to rainfall.Branching rate was greater in the N0 treatment with significant sward height effects confined to a negative relationship with local sward height within treatment plots on one occasion; it was negatively related to rainfall. The ground level red:far red light ratio was negatively related to local sward height. The total live weight of sheep carried in the No treatments was 0·7 of that in the N1 treatments.Expected photomorphogenic responses by we were confined to stolon extension. It was concluded that on the poorly drained clay-loam soil used in this study the effects of sheep, in interaction with climatic factors, had an overriding effect on clover branching rate and the ultimate species composition.

Notes: Three experiments (2a, 2b and 2c) were carried out to examine the effects of different grazing intensities imposed during spring on subsequent herbage composition and milk production measured in summer.Increased intensity of grazing imposed during spring (including the period of reproductive development in ryegrasses) produced swards in early summer with lower pre-grazing herbage masses, which contained higher concentrations of green leaf, clover and digestible nutrients, but lower concentrations of grass stem and senescent material.In the first and second experiment cows were given a common daily allowance of total herbage dry matter (DM). The cows grazing on low-mass swards in early summer produced larger daily yields of milk, fat and protein than those grazing on the high-mass swards.In the third experiment, cows were given a common daily allowance of green leaf DM from three swards which differed in pre-grazing herbage mass and in herbage composition. The allowances of total DM required differed widely between the treatments. There were no significant differences in milk yields between the swards despite the large differences in herbage composition.The practical implications of these results are discussed.

Notes: The fermentation characteristics and chemical composition of 57 first-cut and 30 second-cut samples of grass silages, made in bunker silos on commercial dairy farms in Wales in 1990, and treated with a nominal 61 t−1 of an acid salt-type additive at ensilage, is described. Typical chemical composition of grass cut for ensilage was 156 g kg−1 dry matter (DM) and 28 g kg−1 water soluble carbohydrate (WSC), with 181 g (kg DM) −1 crude protein (CP) and 232 g (kg DM) −1 modified acid detergent fibre (MADF). The effect of additive use was to produce silages with DM 230 g kg−1 pH 3·93, ammonia N 70 g kg−1 total N, with residual WSC 35 g (kg DM) −1, lactic acid 83 g (kg DM) −1, total acids 118 g (kg DM) −1 and butyric acid 0·7 g (kg DM) −1. No significant differences were found between first- and second-cut silages. Silage fermentation was restricted (i.e. lactic acid less than 60 g kg DM−1) in only 20% of the samples.It is suggested that on commercial farms the application rate achieved may be insufficient to produce a restricted fermentation.

Notes: Two experiments are described in which the effect of grazing or defoliating mixed swards at different times over winter and spring on clover content and development was investigated.In the first experiment swards were grazed with sheep (to about 3 cm) for a short period in (a) November, (b) November, January and March, (c) March or (d) not at all, in three consecutive years. All swards were grazed intermittently during the grazing season with cattle and cut for silage once each year. Each plot received either 0 or 50 kg N ha−1 in March.The effect of N fertilizer was to reduce clover content in each summer and clover growing point density in the third year.In two of the three years, treatments involving grazing in March had lower subsequent net annual herbage accumulation compared with the other two treatments and higher clover content in summer of the third year. Reduction in growing point density in all plots during the grazing season was associated with cattle grazing when conditions were wet, suggesting that stolon burial was implicated. Grazing with sheep in November, January and March resulted in significantly more visible (when counted in situ) clover growing points in April in year 2 and more total growing points (counted after dissection of turves) in the third year than the November grazed and ungrazed treatments which had, on occasions, higher grass tiller density.In a microplot experiment, high herbage mass standing over winter was associated with lower potential photosynthesis per unit clover lamina area and lower growing point density in March. Cutting herbage in March to 2-3 cm resulted in higher clover content and higher growing point number per unit stolon length. The latter was significantly correlated with total irradiance and red: far red at the canopy base. Potential photosynthesis of clover was not affected by cutting in March.It is concluded that growing point density can be increased by grazing or cutting during winter or spring. However, in order for these new stolons to contribute to clover yield during the summer, they have to be maintained until then by ensuring that competition from grass is minimized by keeping the sward short in winter and spring and avoiding the burial of stolons during grazing.

Notes: Comparative herbage characteristics and sheep production (ewes and lambs until weaning and lambs thereafter) from swards of Aurora (very early flowering), Frances (early flowering), Talbot (intermediate flowering) and Melle (late flowering) varieties of perennial ryegrass (Lolium perenne) were studied under a continuous variable stocking management based on sward surface height guidelines. The varieties were assessed as grass-only (215 kg N ha−1 fertilizer) and grass/clover (83 kg N ha−1 fertilizer) pastures.Over 2 years (1985-86) total annual lamb production per hectare from grass-only swards of Aurora was 19% more than that from Frances despite similar herbage productivity. Differences between the varieties in lamb output were more pronounced as grass/clover swards, with Aurora producing 29 and 18% more lamb than Melle and Talbot respectively and with Frances also giving 16% more than Melle. Overall lamb production from grass/clover swards was 10% more than that from the grass-only pastures, mainly due to 69% advantage in individual lamb growth rates after weaning. Herbage organic matter digestibility, during the post-weaning period, was higher on grass/clover than on grass-only swards, and similarly with Aurora versus the other varieties. Under a frequent cut simulated grazing regime the relative herbage productivity of the four varieties differed, with Aurora 13% less productive than Frances.The results are discussed in relation to the limitations of assessing performance under cutting, and the significance of the interaction in animal productivity between the two sward types.

Notes: Two silages were made from perennial ryegrass ensiled without wilting in 2-t capacity silos with the application of either formic acid or an enzyme mixture of cellulases and hemicellulases. Effluent losses were monitored over the ensiling period. Subsequent silage analysis showed that the enzyme-treated silage had higher concentrations of residual water soluble carbohydrate, lactic acid and acetic acid, and lower concentrations of cellulose, ADF and NDF. Effluent production was higher with the enzyme silage (formic acid, 211 1 t−1; enzyme, 2671 t−1). The silages were either offered as the sole diet or supplemented with rapeseed meal at two levels (60 or 120 g fresh weight kg−1 silage DM offered) to growing steers equipped with rumen cannulae and T-piece duodenal cannulae. Apparent whole tract digestibilities for DM, OM, N, ADF and NDF were similar for all diets although nitrogen retention (g d−1) was increased with supplementation of both silages (formic acid, 21·1; formic acid + 60 g, 23·5; formic acid+ 120 g, 28·5; enzyme, 22·6; enzyme + 60 g, 25·8; enzyme+ 120 g, 31·6). Rumen pH, ammonia and total volatile fatty acids patterns were similar. Supplementation increased the amount of organic matter apparently digested in the rumen (ADOMR) with formic acid-treated silage but not with enzyme-treated silage. Liveweight gains were similar for both unsupplemented silages (0·49 kg d−1). These increased to 0·55 and 0·65 kg d−1 for formic + 60 and formic + 120 respectively. Liveweight gains for the corresponding enzyme-treated supplemented diets were 0·81 and 0·91 kg d−1 respectively. Liveweight gains on supplemented enzyme-treated diets were significantly (P 〈 0·05) greater than those on formic acid-treated diets.

Notes: Estimates of the diet of resident intact steers grazing four different tropical grass/legume pastures were made by two methods. In the first, oesophageal fistulated (OF) steers were used on three days and the botanical composition of the extrusa determined microscopically. The second method measured the carbon ratio (δ13C) of the faeces of the resident steers over three days, and the percentage legume in the diet was calculated after correction for digestibility differences between the grass and legume components. Estimates of legume percentages in the diet by the two methods differed markedly; OF steers selected a diet containing much more legume than did resident steers, the regression of extrusa estimates on δ13C having a negative slope.This, and other evidence, clearly shows that estimates using OF steers of the diet of resident cattle grazing tropical grass/legume pastures can be most unreliable. Reasons for this unreliability are briefly discussed.

Notes: Lucerne (Medicago sativa), field wilted to 330 g dry matter (DM) kg−1, and whole-plant maize (Zea mays), 383 g DM kg−1, were treated with formic acid (FA) at the rate of 4-5 1 t−1 fresh forage. The effects of FA treatment on proteolysis and amino acid degradation was investigated at several intervals over a 90-d period of ensilage in laboratory silos. Formic acid treatment produced different patterns of pH decline during ensilage of the two forages, suggesting some degree of crop specificity in response to FA treatment. After 7 d of ensilage of lucerne there were increases of 81% in nonprotein nitrogen (NPN), and 104% in free amino acid nitrogen (FAA-N), but with FA-treated lucerne the increases were 39% and 31%, respectively. FA treatment resulted in a reduction in the concentration of most free amino acids in lucerne silage, with the exception of glutamic acid and serine; the branched chain amino acids as well as glycine, tyrosine and proline were significantly (P〈0·05) reduced after 3 d of ensilage. By contrast, FA treatment of maize did not significantly (p〈0·05) affect the NPN content nor was there a consistent pattern in the changes in FAA-N. Formic acid treatment of maize did produce a significant reduction (P〈0·05) in the concentration of most individual free amino acids at 90 d of ensilage. Overall, FA treatment had a more predictable effect on proteolysis and amino acid degradation in ensiled lucerne than in ensiled whole-plant maize.

Notes: Field-wilted lucerne was chopped with a forage harvester at 33 ± 1·5, 43 ± 2·0 and 54 ± 1·8% dry matter, treated and ensiled in laboratory silos during four cuttings in each of two years. Treatments were control (C), sugar addition at 2% of fresh weight (S), inoculum applied at 3 × 105 bacteria g−1 herbage (I), and sugar and inoculum combined (IS). Duplicate silos were opened and analysed after 1, 2, 3, (4 or 5), 7, 14 and 60 d of fermentation. The initial rate of proteolysis of lucerne protein decreased with increasing dry matter (DM) content of the lucerne, and was not influenced by the year, cutting or silage treatment. Inoculation increased (P〈0·05) the rate of pH decline for all silage dry matters, and shortened the lag time prior to pH decline with 33 and 43% dry matter silages. Sugar addition had no effect on rate of pH decline or lag time. Inoculation and sugar addition both lowered final pH, acetic acid, ammonia (NH3), free amino acids (FAA) and soluble non-protein N (NPN) in silages (P〈0·01) and increased lactic acid content with 33 and 43% dry matter silages. Only inoculation was beneficial at 54% DM with no difference between I and IS. The influence of forage characteristics (epiphytic lactic acid bacteria, buffer capacity and sugar:buffer capacity ratio) on treatment effectiveness varied with dry matter content.

Notes: A study was conducted to explore the possibility of a synergistic effect of an inoculum of lactic acid bacteria and sodium bicarbonate in improving the nutritive value of lucerne silage. Twenty Holstein heifers (live weight 183 ± 9·4 kg) were assigned to four dietary treatments consisting of: lucerne uninoculated or inoculated prior to ensilage and then either unsupplemented or supplemented with NaHCO3 (40 g kg−1 dry matter (DM)). The lucerne silage contained 320 g kg−1 DM and constituted 600 kg−1 diet DM. The animals were fed once daily for 90 d and samples of jugular blood were analysed for plasma ammonia and indices of blood acid-base status. Inoculation of Lucerne reduced (P〈0·01) silage pH but had no other effect on silage composition. In the absence of NaHCO3, liveweight gain and organic matter intake were improved by inoculating lucerne prior to ensilage; however, in the presence of NaHCO3, inoculation reduced growth rate but had no major effect on intake. Dietary treatment did not (P〉0·05) affect the concentration of plasma ammonia or measures bf blood acid-base status. The results suggest that NaHCO3 may have nullifled any potential benefit of inoculating lucerne silage to improve its nutritive value for heifers.

Notes: Grass production can be predicted using a simple model whose inputs include daily meteorological variables. Changes in both daily temperature and the soil water balance can be expected as a consequence of anthropogenic increases in the CO2 content of the atmosphere. Possible consequences of such changes for grass production are then predicted using the model. These indicate that, for the UK, patterns of grass production could be shifted significantly. Greater grass growth in the spring would follow from the increase in temperature, particularly on drained land where growth is not constrained by water logging. However, grass growth would be depressed by the mid-season soil moisture deficit, and this again is more marked on drained land, it is concluded that, under a changed climate, the drainage of grassland to enable early season access to the land, together with sound management to optimize output, will be even more important than at present.

Notes: A method of growing cereals with no input of N fertilizer was tested. Two experiments are reported in which white clover (Trifolium repens L.) was used to supply the nitrogen requirements of the cereal. Spring barley, spring oats and winter barley were direct drilled into an established clover crop and grown with the legume as an understorey. The yield of whole crop cereal, for ensilage, and yield of cereal grain were similar to those grown by traditional methods. In the first experiment, clover survived adequately to be used again, but in the second experiment it was killed by a very high slug population. A method of slug control by mob stocking with sheep is discussed. Where clover survived, no weed, insect or disease problems were encountered. The technique offers a possible method of reducing the environmental problems arising from the use of nitrogen fertilizers.

Notes: In two experiments with ryegrass/white clover mixtures, the proportion of clover was measured before and after cuts which removed 8-75% of above-ground biomass. Cutting was found to reduce the proportion of clover leaf area in the crop in both experiments, sometimes by as much as two-thirds, and the proportion of clover dry weight, by up to half, in one of them. That is, the harvested material contained a greater proportion of clover than did the sward before the cut. This disproportionate removal of clover was due to clover having a greater proportion of its leaf near the top of the canopy than grass. It showed that preferential removal of clover occurs as a result of the purely passive selection by a mower, not only as a result of grazing by animals which may be capable of active as well as passive selection.Despite the disadvantage to clover of losing more of its leaf area than grass, and in some cases more of its dry weight also, when the mixture was cut, the clover content of the sward did not decrease during the growing season as a whole. This was because, where no nitrogen fertilizer was applied, clover had a greater relative growth rate (RGR) than its companion grass during the growth periods between cuts and this increased its percentage of the mixture. Even where nitrogen was applied, clover equalled the RGR of grass and maintained its proportion of the crop, except in one instance.

Notes: Seven varieties of white clover (Trifolium repens L.), of varying leaf size from large to small, were sown with perennial ryegrass (Lolium perenne L.) in 1985, at an upland site, and compared over three harvest years under a cutting management (5-6 cuts), and under continuous grazing by sheep. Fertilizer N input totalled 80 kg ha−1 in both the cutting and the grazing trial. The same varieties were included in two official National List (NL) trials sown the same year at a nearby site; these comprised a yield trial with 6-7 cuts and a persistency trial mown very frequently (17 cuts) to simulate intensive grazing.At the upland site the large-leaved varieties, Milkanova and Blanca, were the highest yielding under cutting (mean 3·3 t DM ha−1), and the small-leaved S184 and Kent the lowest yielding (mean 2·3 t DM ha−1). The rankings were reversed under grazing (corresponding yields 1·1 and 2·1 t DM ha−1). The medium-leaved varieties Donna, Menna and Grasslands Huia behaved similarly to the large-leaved varieties. Ranking order in the cutting trial was similar to that in the NL trial.Ground covers after three harvest years differed significantly only under grazing, when the small-leaved varieties had a 2-3 times greater cover than the larger-leaved varieties. A poor separation of the varieties in the NL persistency trial suggests that defoliation was not sufficiently severe to simulate intensive grazing.These comparisons indicate that the performance of clover varieties under the cutting regimes used should not be extrapolated to continuous sheep grazing.

Notes: Two contrasting decision rules for adjusting stock density to control the sward height of continuously grazed grass swards were tested and developed. One rule calculated the adjustment as a percentage of the existing stock density (Percentage Rule); the other related the adjustment to estimates of the bulk density of the grazed horizon and individual animal intake (Absolute Rule). Both decision rules related the adjustments to the change in sward height over the previous week and to the deviation from the target value. The decision rules were tested by continuously grazing lactating ewes and then dry ewes after weaning with a target sward height of 4 cm on 0·33-ha plots with stock density adjusted by varying animal numbers. The Percentage Rule failed to increase the stock density sufficiently rapidly when grass growth was accelerating, leading to increasing deviation in sward height from a 4 cm target value. The Absolute Rule succeeded in controlling sward height once the bulk density term had been correctly adjusted. Pre-emptive adjustment of stock density in anticipation of a change in grass growth rate marginally improved the control that was achieved by the Absolute Rule.

Notes: In three successive years, sward height was maintained at 3, 5, 7 or 9 cm on grass swards receiving a total of 300 kg N ha−1 in six equal monthly dressings from April, and on grass/clover swards receiving 50 kg N ha−1 as a single dressing in early spring. From turnout in April until weaning in July, 64 ewes and their lambs (mean litter size 1·5) were continuously grazed at the four sward surface heights on the two sward types. White clover content of grass/clover swards remained low throughout the experiment ranging from 0·2 to 7·4% of the herbage mass. During the first two years, lamb gains averaged over sward types were 204, 260, 285 and 308 g d−1 up to weaning, while in the third year gains were 238, 296, 296 and 260 g d−1 on 3, 5, 7 and 9 cm swards respectively. Ewes lost live weight on 3 cm swards but apart from this sward height had little effect on performance. During the autumn, weaned lambs gained — 27, 87, 147 and 167 g d−1 on 3, 5, 7 and 9 cm swards respectively. Sward type had only a small effect on the performance of lambs up to weaning but in the autumn, mean gains of weaned lambs were lower on grass/N swards (73 g d−1) than on grass/clover swards (115 g d−1). Relative to 3 cm swards, carrying capacities of 5, 7 and 9 cm swards were 0·76, 0·57 and 0·52 respectively from turnout to weaning and 0·66, 0·52 and 0·44 respectively during autumn. Grass/clover swards carried 0·67 of the ewes carried by grass/N swards from turnout to weaning and 0·51 of the live weight carried by grass/N swards during autumn.The reaction of the two sward types to sward height did not appear to differ but in the third year there was evidence of a reduction in white clover content when swards were grazed at 9 cm. The data suggest that lamb growth rates will increase as sward height increases up to 9 cm and the evidence for this was stronger with weaned lambs in autumn than with suckling lambs in spring.

Notes: Anatomical structure and fibre chemistry influence the digestibility of forage grasses. The objective of this study was to evaluate the anatomical structure, digestibility, and fibre composition of leaf blades from a high alkaloid and two low alkaloid cultivars of reed canarygrass (Phalaris arundinacea, L.) and one cultivar of tetraploid hybrid ryegrass (Lolium hybridum, Hausskn.). Cultivars were grown in a greenhouse in a randomized complete block design with four replications. Leaf blades were either cut into 10-mm sections or dried and milled to disrupt anatomical structure.Reed canarygrass had smaller cells and airspaces and slower tissue digestion than ryegrass. The in vitro disappearance of ryegrass sections in buffered rumen fluid was 60% greater (P〈0·01) than that of reed canarygrass after 6, 12 and 24 h of digestion. By contrast, the in vitro disappearance of milled ryegrass was similar to or less (P〈0·05) than that of reed canarygrass. In vitro dry matter digestibility and fibre composition of the grasses were similar except for acid detergent fibre, which was greater (P〈0·01) in ryegrass than in reed canarygrass. Reed canarygrass cultivars were similar in anatomical structure, digestibility, and fibre composition. It was concluded that the digestion of reed canarygrass, relative to ryegrass, was reduced by the compact arrangement of tissues and that alkaloid content did not influence the digestion of reed canarygrass cultivars.

Notes: Four silages were prepared from grass treated with additives designed to produce different extents of fermentation in the silo. The additive treatments were: formic acid at 5 l t−1; a bacterial inoculant (Ecosyl, ICI plc); the inoculant plus molasses at 20 kg t−1; and a noadditive control. All silages were well preserved. Formic acid severely restricted the extent of fermentation, the concentration of lactic acid being only 50% of that seen for the other treatments, all of which were similar in lactic acid concentrations.The silages were offered ad libitum, either as the sole component of the diet or together with three supplement treatments to 16 British Friesian cows, in four 4 treatment × 4 period Latin squares with periods of 28 d duration. The supplements were: a barley-based mixture at 5 kg d−1 (B); a high-fat, high-protein product at 2 kg d−1 (FPI) and at 3 kg d −1 (FP2); both FP treatments were given with 1 kg d−1 of molassed sugarbeet pulp. A preliminary experiment, using three lactating, rumen-cannulated cows in a 3×3 Latin square design with 28-d periods, provided information on rumen digestion when the supplements were given with a separate, non-experimental silage.In the preliminary experiment, neither of the FP treatments influenced the molar proportion of the major rumen volatile fatty acids compared with treatment B; nor were there any depressive effects of the FP treatments on silage intake compared with treatment B.In the main experiment, the intake of silage with the inoculant treatment was less than that with the other treatments, the effect being generally significant (at least P〈0·05) for all three supplements. When the silages were given unsupplemented, there were differences in the concentration (P〈0·001) and yield (P〈0·01) of milk fat, both of which were lowest for the no-additive control and highest for the formic acid silage. When supplement B was given, the concentration and yield of milk fat were lowest for the no-additive control and the concentration and yield of milk protein were highest for the formic acid silage. For all silages both FP treatments tended to depress silage intake and reduce the concentration of fat and protein in milk compared with treatment B.Although there were clear indications of differences in nutritional characteristics between the silages, there was little evidence that the differences between silages influenced the responses to changes in the composition of the supplements.

Notes: Relative sheep production from Aurora (very early flowering), Mellra (late-flowering tetraploid) and Aberystwyth S23 (late flowering) perennial ryegrass (Lolium perenne L.) varieties was compared during harvest years 4-6 (1988-90) as grass only (200 kg N ha−1) and grass/clover (75 kg N ha −1 in 1988, 0 kg N ha−1 in 1989 and 1990) at Bronydd Mawr Research Centre (310-363 m) in mid-Wales. The pastures were continuously stocked with Beulah Speckled Face ewes and their Suffolk cross lambs from spring to mid-July. From late July to early November only the weaned lambs grazed the swards.Mean (1988-90) total annual lamb production per hectare from Aurora and Meltra was 70% and 16% more than that from S23. However, the difference between both varieties and S23 was much greater as grass/clover (Aberystwyth S184 small-leaved type) than as grass-only swards. Differences between the grasses in individual lamb growth rates were most pronounced during the post-weaning period, when that on Meltra was 38% and 23% more than on Aurora and S23 respectively.Mean annual lamb output from grass/clover swards was only 70% of that from grass-only swards during the 2 years when the former swards received no fertilizer N. Averaged over the 3 years (1988-90) individual lamb liveweight gain post weaning was 38% higher on grass/clover than on grass-only swards.The results are discussed in relation to those for the first 3 harvest years (1985-87). It is concluded that, although Aurora was less persistent than both late-flowering varieties, its superiority in providing an average of 29% more lamb output than S23 during the critical spring period (up to early June) would be of considerable practical significance in upland sheep systems, as would be the overall superiority of the tetraploid Meltra over S23.

Notes: Replicated field trials were carried out at 23 sites in England and Wales between 1986 and 1988 examining the response of first-cut grass silage to different levels of early winter- or spring applied potash on dry matter (DM) yield and herbage composition. Residual effects at the second cut were measured. In 1986/87 and 1987/88, the effect of additional potash at second cut was examined.Yield responses at first cut were measured at 13 sites (P〈0·05). Optimum potash rates (K-opt) ranged from 0 to over 160 kg ha−1, the highest rate tested. The mean rate of response up to K-opt at responsive sites was 10·4 kg DM (kg K2O)−1. Herbage K% increased with potash rate regardless of the requirement for maximum economic yield. Increasing potash rate reduced herbage Mg% by less than 0·020% which was less than the effect of soil Mg level. An increase of 50 mg 1−1 in soil Mg (0-7·5 cm depth) increased herbage Mg by 0·034%. Early winter application of potash was generally as effective as spring application though it gave slightly lower herbage K and higher herbage Mg concentrations. Offtake of potash (K2O) at first cut was on average 12 kg ha−1 more from spring than from early winter application.Herbage analysis for N:K ratio was the best indicator of potash requirement. Regression analysis of the N:K ratio of herbage in control (nil potash) treatments against K-opt at first cut gave an r2 value of 51·4% (***). For herbage total K%, r2 was 39·7% (**) and for soil K (0-7·5 cm depth) it was 21·3% (*). Taking account of soil K below 7·5 cm depth was important at some sites, particularly those with a history of arable cropping and associated soil cultivation.Residual effects of a single early winter or spring application were measured, but additional potash applied for second cut was generally more effective. Optimum rates of potash for second cut were not determined.

Notes: Substantial annual fluctuations in the performance of arable silage mixtures, comprising Minerva forage pea and Goldmarker barley, were observed from ten annual sowings between 1977 and 1986, Total dry matter (DM) yield varied between 2·5 and 11·5 t ha−1. Dry matter content also ranged widely from 10·3% to 20·0% and there was a large variation in the proportion of peas in the DM (0·44 to 0·90). Almost 80% of this yield variation was due to the fluctuation in pea performance and over 60% of all yield variation was related to the variation in sunshine hours and air temperature.In 1983 and 1984 differences in seed rate of between 20 and 140 kg ha−1 of Minerva and 80 and 160 kg ha−1 of Goldmarker influenced the forage composition at harvest, with the pea component capable of outgrowing and suppressing the other species when sown at over 80 kg ha−1. Very high yields of peas were associated with increasing stress on the undersown grass re-seed and were considered undesirable.It was concluded that sowing rates of between 120 and 160 kg ha−1 for barley and a maximum of 60 kg ha−1 for peas would, in most years, provide the best compromise between attaining good arable silage yields and avoiding excessive dangers of damage of undersown grass re-seeds.