摘要:

AbstractThe effect of cow slurry N on productivity and white clover content was compared with that of mineral fertilization in a natural grassland sward. Fertilizer was applied at two different N rates as split applications of ammonium nitrate, or as cow slurry (145 or 290 kg N ha−1in the first year and 120 or 240 kg N ha−1In the second year)‐ In the first year, fertilizer N produced higher dry matter (DM) yields than the slurry treatments. Nitrogen efficiency and clover content reduction were higher for the mineral treatments, the efficiency being lower for the higher rate of N application. In the second year, N supplied by the slurry gave the same productivity, N efficiency and white clover content reduction as that from the mineral N fertilization; higher efficiency in the second year being due to favourable weather conditions and low white clover contents. The high N efficiencies of the slurry compared with the fertilizer N treatments were attributed to the dilution of the slurry and to split applications over the year. Yield differences between treatments were due mainly to the grass component of the sward. Competition between grasses and other species, and white clover for mineral N resulted in a reduction in the white clover content in those treatments in which more N was supplied, whether it came from the mineralization of slurry or from the fertilizer N ap

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02031.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractMechanical and chemical treatments to accelerate the drying of cut lucerne were evaluated under laboratory conditions. Plant material was treated with a 016 M solution of potassium carbonate (K2CO3) and/or lightly pressed between a pair of smooth rollers (roll‐conditioning).Drying times to 33% moisture content (MC), expressed on a dry weight basis (dwb), were reduced by 49% by roll‐conditioning, 76% by K2CO3) treatment and 77% by the combined K2CO3+ roll‐conditioning treatment. The main benefit from combining the two forms of treatment was an improved uniformity of drying; when whole shoots were at 61% MC (dwb) the difference between leaf and stem moisture contents was reduced by 28% (roll‐conditioning), 38% (K2CO3) and 54% (K2CO3+ roll‐conditioning) relative to the untreate

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02032.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractDiploid and tetraploid perennial ryegrass swards were managed under an intensive silage system over 3 years. The swards were subjected to five tractor wheel pass treatments to simulate combinations of silage operations in the field from cutting, tedding, lifting and fertilizing. Wheel tracking was applied uniformly over the swards after June, July, August and October cuts each year.Tractor wheel passes caused mean reductions in herbage dry matter (DM) yield during successive years of 14%, 6% and 9% compared with their absence, and frequent or delayed wheel passes affected yield more adversely than infrequent or undelayed wheel passes. Nitrogen and mineral concentrations in herbage and nutrient offtakes were also generally reduced but organic matter digestibility (OMD) was unaffected. Soil assessments each autumn showed that soil bulk density increased in the wheel‐pass treatments, particularly when frequently applied. The two sward types responded in a similar manner to the wheel‐tracking treatments, probably because they had similar cushioning capability, the disadvantage of the tetraploid in terms of fewer tillers in relation to the diploid being compensated for by larger tiller size. Soil compaction, with its adverse effect on sward growth vigour, and direct wheel damage to young regrowth will be lessened by minimizing wheel traffic on silage swards and undertaking operations over short rather than long peri

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02033.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractDairy farming systems are important sources for the emission of a number of materials that include various forms of nitrogen (NO3−, N2O and NH3) with potential environmental impact. The present paper is a systems synthesis study and assesses the likely impact of changes in management on N flows and losses. These include tactical fertilizer adjustment, slurry injection, maize silage production and the use of white clover as an alternative to fertilizer N. Implications for greenhouse gases (N2O and CH4) and support energy have also been considered. Substantial reductions in inputs and total and proportional losses by all die options considered were predicted by this study. Thus, using a tactical approach to fertilizer application and injecting slurry or using 50% maize silage reduced overall N losses from 160 (under conventional management) to 86 and 109kg Nha−1respectively. Combining both possibilities reduced losses further to 69 kg ha−1. Although use of white clover, especially at low contents in the sward, was the most effective regime to reduce losses, this was at some cost to production so that losses per livestock unit (LU) did not always differ from those under other managements. Changing the N management had consequences for greenhouse gas emission with an estimated maximum 70% reduction in N2O release. The effects on CH4emissions were relatively small. Substantial reductions in support energy costs were also obtained: these arose mainly from the reduction in fertilizer N use, which represented 66% of the total support energy in the original s

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02034.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractAn experiment was designed to examine the effects of partially replacing extensively fermented grass silage with varying proportions of fresh grass (0, 0–33, 0–67 and 100) on rumen fermentation, degradation of dry matter (DM) and rate of outflow of liquid and particulate phases from the rumen with four mature Limousin steers. The fresh grass had a higher pH and water‐soluble carbohydrate and lower ammonia‐N and lactic acid concentrations than the silage. Partial replacement of silage with fresh grass resulted in a reduction in rumen ammonia concentration, and in the proportion of rumen propionate, i‐butyrate andn‐valerate and an increase in the proportion of rumen acetate and in both die particulate and liquid outflow rates from the rumen. These changes in rumen fermentation parameters could account for increases in animal performance in situations in which grass silage is partially replaced with

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02035.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractCattle slurry (50 m3ha−1equivalent to 68 kg N ha−1) was applied to grassland plots 70 d (early application) and 34 d (late application) before ensiling and the retention and survival of slurry and epiphytic micro‐organisms on the growing herbage were examined and compared with those on herbage from corresponding fertilizer‐treated plots. The populations of lactic acid bacteria, enterococci and enterobacteria on herbage increased dramatically after slurry application. Thereafter, numbers of lactic acid bacteria declined, although they were always higher than on untreated herbage. Number of enterobacteria also declined but were higher on chopped grasses at ensiling [106colony‐forming units (CFU) g−1fresh matter (FM)] than they were on hand‐cut. unchopped herbages at all previous sampling times. Clostridia numbers were lowest on untreated and highest on slurry‐treated herbage, particularly after the late application (>103CFU g−1FM). Herbage was harvested 70 d and 34 d after slurry application, chopped and ensiled in laboratory silos. All herbages, irrespective of treatment, had low dry matter (DM) values (ranging from 149 to 170 g kg−1FM) and fairly low water‐soluble carbohydrate (WSC) concentrations (130 g kg−1DM or less). The initial rate of pH decline up to 4 d was most rapid in slurry‐treated herbages, with all pH values falling to4. 5. accompanied by a marked decline in lactic acid concentration. Lactic acid‐fermenting Clostridia increased in numbers, reaching peak values of 107CFU g−1FM by day 21, remaining high until opening, and were probably responsible for increases in butyric acid levels in all silages, with the highest concentrations occurring in those prepared from slurry‐treated herbages. The results suggest that, although some faecal lactic acid bacteria may have beneficial effects in the early stages of fermentation, Clostridia from slurry can survive on herbage for extended periods. The results indicate that the potential for growth of Clostridia in silage may be independent of source or size of the initial population even at tow pH, if

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02036.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractA perennial ryegrass/white clover sward, which had been grazed for over 2 years, was cut at 1‐, 2‐, 3‐ or 6‐week intervals from 18 April to 28 November 1986. Two rates of fertilizer N application in spring, 0 and 66 kg N ha−1, were compared. Perennial ryegrass growth was studied in three 6‐week periods, beginning on 18 April, 18 July and 17 October. Clover growth was studied in the same three periods and described by Fisher and Wilman (1995)Grass and Forage Science,50, 162–171.Applied N increased the number of ryegrass tillers m−2, the rate of leaf extension and the weight of new leaf produced tiller−1and m−2per week. Increasing the interval between cuts reduced the number of ryegrass tillers m−2and increased the rate of leaf extension, weight tiller−1and the weight of new leaf produced tiller−1week−1. Increasing the interval between cuts increased the weight of new ryegrass leaf produced m−2where N had recently been applied, but otherwise had little effect on the weight of new leaf produced m−2. Applying N favoured the grass in competition with the clover in every respect, whereas increasing the interval between cuts only favoured the grass, compared with clover, where N had recently been applied; where N had not been applied, the ratio of ryegrass tillers to clover growing points in the sward was very little affect

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02037.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThree small plot experiments were conducted to investigate the effects of species of grass and forbs, defoliation regime, inclusion of white clover and forb blend on the herbage dry matter (DM) yield, botanical composition and mineral content of swards managed with zero fertilizer inputs. The results of all three experiments were characterized by decline in herbage production and large variations in treatment effects over the harvest period.When sown singly with a standard grass mix the species that competed well with grasses and produced annual forb herbage yields greater than 20 t DM ha−1were black knapweed, oxeye daisy, ribwort plantain, burnet, birdsfoot trefoil, chicory, kidney vetch, red clover and white clover. When sown singly with a standard forb mix, grass species significantly affected the annual yield of total (P<005). grass (P<001) and forb (P<0.001) herbage. The species that most surpressed the yield of forbs were common bent, Yorkshire fog and perennial ryegrass. Those that allowed for the highest yield of forbs were rough meadow grass, sweet vernal grass and crested dogstail. Averaged over the three harvest years, defoliation regime did not significantly affect herbage production, but the inclusion of white clover in mixtures increased the yield of grasses (P<0.01) The use of rosette‐type forb blends increased forb yield (P<0.01), compared with erect‐type blends.The effects of treatments on herbage N and mineral contents and yields were inconsistent. However, there was some evidence to support the view that the presence of forb species in swards can result in greater contents of minerals in herbage, compared with grass‐only

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02038.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractDevelopment of white clover stolons (Trifolium repens) was compared when grown in rejected areas and in adjacent defoliated areas over 28 days in May ‐ June in continuously stocked grass/white clover swards. In the cut areas more branches were borne on stolons with more but shorter internodes and shorter petioles than in the rejected areas. Red (R)/far red (FR) ratio at the base of the cut sward was significantly higher than in the rejected sward.Five experiments were carried out in which red light‐emitting diodes (LEDs) supplied supplementary irradiation at the node of the youngest fully expanded leaf on white clover stolons growing in association with dense canopies of perennial ryegrass. Axillary bud/branch length was the only significantly affected aspect of development that was measured, irradiation enrichment increasing length by about three‐fold over a 2–4 week period. One of the experiments involved identification of the site of perception of the R/FR effect. Natural and supplementary light were excluded from the stolon (by covering with a 2‐cm layer of black beads), petiole (by wrapping in aluminium foil), both or neither and showed that exposure of the stolon/ petiole base to supplementary light was necessary to stimulate axillary bud growth.It is concluded that the relative content of red light, and possibly absolute level, in irradiance at the base of the canopy in rejected areas is implicated in the young branch growth and that release of the buds can be achieved by defoliation, presumably due to increasing the red light content; however, the effect of increased photosynthetically active radiation (PAR) reaching stolons and young leaves cannot be discounted as an addition

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02039.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe intakes of rush and grass by goats grazing rush‐infested reseeded pasture (rush ground cover, 5.9%) were measured in three periods between July and September in one year, usingn‐alkanes as dietary markers. Diet composition and intakes were measured at intertussock sward heights maintained at 3–4 cm and 5–6 cm and at an intertussock sward height maintained at 3–4 cm where the rushes had previously been grazed by goats to reduce rush green stem height to 0.75 of that of ungrazed tussocks.There was no effect of intertussock sward height or initial rush green stem height on the dietary proportion (overall mean 0.51) or dry matter (DM) intake of rush but there was an effect of period, which was related to changes in sward conditions over the experiment. Rush intake was positively related to the amount and accessibility of green rush stems and grass intake to intertussock sward height. Digestibility of DM of the diet, measured usingn‐alkanes, was high (overall mean 0.71), suggesting that the nutritive value of the rush is greater than previously estimated fromin vitrodigestibility measurements. Under these conditions, it appears that the goats select a mixed diet and the results are consistent with animals selecting food items to maximize their rate of nutr

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02040.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY