摘要:

AbstractAn examination was made of the effects of different spring treatments on the growth of white clover in a ryegrass/white clover sward. Plots were either cut once (in February, March or April) or twice (in February and April) or left uncut. Nitrogen was applied to half of the plots in each instance. The clover was sampled at intervals of approximately 3 weeks from February to June to determine numbers of leaves and growing points and weights of plant parts. Rates of leaf appearance were also observed and estimates were made of total herbage mass from ground‐level cuts.Percentages of white clover in the herbage were higher in unfertilized than in fertilized plots and in defoliated than in undefoliated plots. The percentage increases that followed defoliation were usually maintained into later regrowth, showing that clover content was not automatically reduced as herbage mass increased. Increases in growing points were recorded after the beginning of April in defoliated unfertilized plots but not in undefoliated fertilized plots or in plots fertilized and defoliated twice during the spring period, in which numbers fell substantially.Inverse relationships were found between rates of leaf appearance, or the number of green leaves retained per stolon, and herbage mass, whereas heights of clover and grass leaves and the percentage of dry matter allocated to petiole rather than leaf in the clover increased with increasing herbage mass.We suggest that the observed differences between spring treatments in clover percentage result primarily from their differential effects on the formation and death of tillers and growing points in the early stages of regrowt

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01959.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractEffects of sowing date, fungicide seed treatments, and the head smut fungus Ustilago bullata Berk, on establishment, herbage, and seed production of prairie grass cv. Grasslands Matua (Bromus willdenowii Kunth) were measured in autumn‐ and spring‐sown field trials in New Zealand.Autumn seedling establishment from thiram‐treated seed relative to untreated seed was increased by 27% from the earliest sowing (early March), and by 65% from the latest sowing 8 weeks later. Infestation of seed with ustilospores of U. bullata reduced seedling establishment at all but the latest autumn sowing. Fungicide seed treatments had little effect on spring seedling establishment, but V. bullata infestation of seed reduced establishment compared with healthy seed, particularly after late sowings (early November).Herbage production was greater from early than from late sowings in both autumn and spring, and was less in plants grown fromU. bullatainfested seed than in plants from healthy seed. Enhanced autumn establishment from thiram‐treated seed led to improved herbage production when plants were young, but this effect disappeared about 18 weeks after late autumn sowing. Overall herbage production from spring sowing was more than twice that from autumn sowing.A 6‐week delay in autumn sowing led to a 58% reduction in seed production the following summer.Early autumn and spring sowings, together with adequate control of seedling diseases, are likely to give optimum herbage and seed production from prai

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01960.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractGrassland in Britain is a plagioclimax vegetation type. All lies on land originally cleared from forest and, without some form of management, would revert to forest through a process of natural succession. Traditionally managed, unsown grasslands nonetheless resemble more natural grasslands in other parts of the world and contain a substantial proportion of our native flora and fauna. They are also often important for recreational activities. Agricultural intensification over a long period has led to a loss in their extent, species and amenity. Reconciling agricultural and environmental objectives in grassland management is very difficult because increased fertility and production invariably leads to species loss. Current overcapacity in the agricultural industry is leading to the switching of some agricultural support from food production to countryside management. As a result some arable and intensively managed grass is being managed more extensively. However future production technologies may be so efficient that very many fewer stock are required with the result that much marginal grassland may revert once again to forest.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01961.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractWhite clover, (cv. Haifa) and subterranean clover (cv. Seaton Park) were grown in binary replacement series mixtures in the field at proportions of 100:0, 90:10, 50:50. 10:90 and 0:100, and cut every four weeks over three growing seasons from 1985 to 1987 at Scone, New South Wales (NSW) (32°S).Relatively low plant densities minimized competition in 1985, but in subsequent seasons Haifa and Seaton Park competed vigorously for the same resource;.; usually having relative crowding coefficients greater than 1.0, and relative yield totals greater than 1.0 in spring of 1986 and 1987, and autumn 1987. This over‐yielding appeared to be due to some complementarity of leaf morphology and canopy architecture.Haifa severely depressed seed production of Seaton Park in mixtures. Haifa regenerated as an annual in 1986, but as a perennial, from surviving stolons, in 1987 owing to lower maximum temperatures and better rainfall distribution in late summer and autumn of 1987.It is concluded that white clover can survive severe competition from subterranean clover as a seedling, and if moisture allows, may severely depress seed production from subterranean clover, regardless of whether plants are annual or perennial in origin. Spatial separation may minimize competition in average years but competition effects may be severe in seasons with sufficient summer rainfall for perennation of white clover, and seasonal autumn rainfall for germination of subterranean clov

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01962.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractHerbage production and quality of swards of brome grass (Bromus carinatus. Hook and Am) were compared with other commonly sown grasses at two sites in Scotland. At Ayr, the comparison was with perennial ryegrass (Lolium perenneL.), cocksfoot (Dactylis glomerataL.) and timothy (Phleum pratenseL.) under 6‐cut (experiment 1) and 4‐cut (experiment 2) regimes over 3 years with 360 kg ha−1fertilizer N applied annually in each experiment. At Edinburgh, brome grass was compared over 3 years with perennial ryegrass and cocksfoot under a 7‐cut system given 3(X)‐35O kg N ha−1year−1(experiment 3) and with perennial ryegrass, cocksfoot and Italian ryegrass (Lolium multiflorumLam.) under a 4‐cut system given 250–325 kg N ha−1annually (experiment 4).Over the 3 years, brome grass gave 1.18, 6.19 and 1.3% less dry matter (DM) production than the other grasses in experiments 1, 2 and 3 respectively; in experiment 4, it was 1 % less productive than Italian ryegrass but 1.2% more productive than the other grasses. The organic matter digestibility (OMD) of brome grass was lower than that of perennial ryegrass but higher than timothy at Ayr, similar to perennial and Italian ryegrasses at Edinburgh but markedly superior to cocksfoot at both sites. N concentrations in brome grass were higher than in the ryegrasses but lower than in cocksfoot. Mineral composition data showed brome grass to be high in P and K, low in Ca and Mg and very low in Na compared with corresponding concentrations in the other grasses.The variable performance of this brome grass species (B. carinatus) against commonly used grasses in the reported experiments, together with similar evidence from the literature, leads to the conclusion that it is unlikely to be suitable for widespread use in the UK; nevertheless, it has shown some promise in droug

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01963.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThis study evaluated the relationships between legume proportion and dry matter (DM) yield, N yield, and herbage N concentration for three binary legume‐grass mixtures In Uruguay. Two identical trials were established, one in 1983 (Trial 1) and another in 1984 (Trial 2) and were evaluated for 2 years. Treatments were white clover (Trifolium repensL.) (WC), red clover (Trifolium pratenseL.) (RC), and birds‐foot trefoil (Lotus corniculatusL.) (BT), each grown with tall fescue (Festuca arundinacea Schreb.) (TF) at four legume proportions, plus pure stands of TF. In Trial 1, annual DM yields of RC‐TF were greater than yields of WC‐TF or BT‐TF and in Trial 2 RC‐TF and BT‐TF yielded more than WC‐TF. The N concentration of either the legume or TF components usually was greater for WC‐TF than other mixtures in both trials. Annual DM yields in Trial 1 were optimized by legume proportions of 47 to 59% for WC, 62 to 67% for RC‐TF, and 57 to 100% for BT‐TF; and N yields were optimized by 70% of WC or RC, and by 100% BT. In Trial 2, which had greater soil‐N availability than Trial 1, optimum DM or N yields were achieved at lower WC proportions than in Trial 1. Changes in legume proportion did not affect legume N concentrations, but N concentration of TF in mixture was always positively and linearly related with legume proportion. It is concluded that DM yields for the first 2 years after seeding were greater for RC‐TF and BT‐TF than for WC‐based mixtures. Herbage DM and N yields of WC‐TF were optimized by lower legume proportions than for RC‐TF and BT‐TF. The N concentration of TF increased linearly with increasing prop

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01964.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractHerbage quality, yields, tiller and plant populations of ‘Grasslands Matua’ prairie grass and ‘Caramba’ tetraploid Westerwolds ryegrass were investigated in a 2‐year field trial on a sandy soil. Plots were either harvested frequently (five to six cuts per year) or infrequently (four cuts). During the first year, herbage was separated into leaf, vegetative and reproductive pseudostem, and analysed separately.With very mild winters and adequate water supply, swards had good persistence and production for 2 years. Total yield in the first year (10.5 t DM ha−1) was similar for both species. Yields in the second year were (t DM ha−1) 13.4 and 18 for Matua and 11.1 and 13 for Caramba under frequent and infrequent cutting respectively. Leaf contributed 58% to yields and reproductive pseudostem 35%. Infrequently cut plots had: 23% higher dry matter yields, primarily due to higher yields of reproductive pseudostem; higher yields of most chemical components and higher contents of water‐soluble carbohydrates and cell walls; lower digestibility and nitrogen content. Cell wall content was consistently higher in Matua but otherwise herbage quality was similar for the two species. It is suggested that prairie grass should be considered as a replacement for spring‐sown Westerwolds ryegrass on sandy soils i

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01965.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSmall swards of white clover and perennial ryegrass were established in Perlite in a heated glasshouse, as either monocultures or mixtures of equal plant numbers. On 26th March, 1984 the swards were moved outside and their growth studied over the period to 29th May. All swards received a basal level of nitrate N to simulate soil mineralization and two‐thirds received additionally the equivalent of 80 kg N ha−1. Over the experimental period (26th March‐29th May) clover maintained its proportion of total mixture dry weight In swards given ‘fertilizer’‐N and increased its proportion in those given only ‘basal’ N, However, clover declined as a percentage of total mixture dry weight during the first period of the experiment when total leaf area index (LAI) and ambient temperatures were low, and increased its percentage later when temperature and LAI had risen. Changes in tiller and stolon growing point numbers were not good indicators of changes in dry weight. Relative yields and relative replacement rates also were not good indicators of relative performance in mixture. Where ‘fertilizer’‐N was applied, clover derived less of its nitrogen from that source than grass although their uptakes per unit shoot dr

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01966.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractAn experiment was conducted to examine the effect of concentrate supplementation on the performance of suckling lambs while grazing at variable levels of herbage allowance. Twenty‐four ewes suckling twin lambs were allocated 55 d after lambing between four grazing treatments (two levels of herbage allowance × two levels of supplementation) in a 2×2 factorial design. The sward consisted of Tall Fescue and was grazed rotationally.Daily herbage organic matter (OM) allowances were 57.0 (H) and 38.5 (L) g OM kg LW−1above 1·5 cm cutting height. Lambs were either supplemented (S)ad libitumwith high‐moisture whole maize grain or unsupplemented (U).Supplement intake during the 60‐d grazing period was 16 kg DM and 17.5 kg DM respectively for LS and HS lambs. The effect of supplementation on lamb growth rate differed significantly between allowances: at the low allowance level, supplementation increased growth rate (287 g d−1vs 226 g d−1), whereas it had no effect at the high level (277 g d−1vs 276 g d−1). Growth rate of unsupplemented lambs was significantly reduced at the low level of allowance compared to the high level (226 g d−1vs 276 g d−1). The effect of sward height on time spent grazing by unsupplemented lambs is described during the

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01967.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA field plot experiment was carried out on an established grassland sward from 1983–88 inclusive to examine the effects of time of application, chemical form of nitrogen (N) and cattle slurry dry matter (DM) content on yield and efficiency of N use. Four forms of fertilizer N (a semi‐organic fertilizer, a combined 2.1:1 (w/w) semi‐organic/calcium ammonium nitrate (CAN) fertilizer, CAN and urea, each supplying 300 kg N ha−1year−1, were applied with or without unseparated or separated cattle slurry at 93 and 73 g kg−1DM respectively, both supplying approximately 150 kg N ha−1year−1. All fertilizers and slurries were applied in three equal dressings (February/March, May/June and July/August). The efficiency of use of fertilizer and slurry N was evaluated by measuring DM yield, N uptake and apparent recovery of N in herbage at all harvests during each growing season.Fertilizer N application significantly increased (P0.05) on first harvest and total herbage yields, nor on N uptakes by herbage at the first harvest in any year. The performance of urea and of CAN was more variable at the second and third harvests relative to that of the semi‐organic or combined 2.2:1 (w/w) semi‐organic/CAN sources which had similar efficiencies of N use. Lower DM production was associated with reduced uptake of N. Values for mean overall apparent recovery of N ranged from 57.9 ± 2.67% for the semi‐organic fertilizer to 50.2±3.05% for CAN.Unseparated cattle slurry and separated cattle slurry produced similar herbage yields and N responses that were lower and more variable than with fertilizer N. The overall mean apparent recovery of N from unseparated cattle slurry was 25.5 ± 5.03% compared to 5.0 ± 4.74% for separated cattle slurry. Efficiency of N use was highest with spring applications and least with mid‐season applications. Recoveries ranged from −29% for separated cattle slurry applied in June 1984 to 56% for unseparated and separated cattle slurry applied in February 1988 and June 1987 respectively. No interactions were recorded between cattle slurry and fertilizer N in terms of DM production or N uptake by herbage.The results of this study support the use of a fertilizer N source, selected on a least‐cost basis, in combination with slurry to promote spring herbage production. For subsequent production, N should be supplied in fertilizer form only. The use of urea is risky under low rainfall conditions. Mechanical separation did not improve th

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb01968.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY