摘要:

An hypothesis relating to the circulation of nitrogen between soil, plants and animals in fertilized grassland is presented. It embodies the results of small‐plot experiments and grazing trials on serai grassland in South Africa. Where the value of land is low in comparison with the cost of fertilizer, it is essential that the maximum response be obtained from fertilizer as well as from excretal N. The assumption that 80% of herbage N is returned as excreta, of which 25% is recovered by the grasses in the first season and 25% in the second season, appears to be in accord with liveweight data. Using average values of soil N and fertilizer recovery under local conditions, it is argued that applying 30 lb N per acre (with an initial heavy dressing) should provide higher percentage recoveries of fertilizer N than fixed annual dressings of 60 Ib N per acre. In grazing trials over five years, in which these systems are compared, the apparent recoveries of fertilizer N in animal liveweight were respectively 22.4% and 11.6%.A distinction is drawn between theinitial build‐upof nitrogen in circulation and thelong term maintenanceof a nitrogen level providing maximum recovery of fertilize

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01174.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Leaf and tiller development along the main shoot of cocksfoot, ryegrass, timothy,Hordeum bulbosum, meadow fescue, S170 tall fescue and an Algerian tall fescue are described. Comparisons between plants grown at two levels of applied nitrogen, and in a heated and an unheated glasshouse, from January to April, 1961, showed that timothy, cocksfoot and, to a lesser extent,H. bulbosumand ryegrass, generally developed leaves faster than the fescues. Numbers of live leaves per shoot, and numbers of actively‐elongating leaves per shoot declined in a similar varietal order. Despite this, the large leaves of the fescues resulted in their having a leaf area per main shoot equal to, or exceeding that of, the other grasses for most of the experiment. In general, rate of leaf appearance, number of live leaves, number of actively‐elongating leaves and leaf length were increased by a high level of N and high temperature, but high tesnperature reduced leaf width and, in some instances, tiller numb

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01175.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Extensive replicated plot experiments were carried out at Henley Manor Farm from 1956–1961 to obtain accurate measurements of herbage production and response to nitrogenous fertilizers under West of England conditions. 356 plots were used; use of the herbage by both cutting and grazing was studied. The principal results are: Grass/ clover swards (containing approx. 35% clover) grown without nitrogenous fertilizer averaged 75 cwt dry matter per acre per annum. Application of nitro‐chalk to initially grass/clover swards reduced the clover content of the herbage. About 133 lb N/annum was required by an all‐grass sward to equal the production of a grass/clover sward without N. Attempts to increase production of grass/clover swards by using N for early growth and relying on clover for mid‐season growth were unsuccessful in 2 out of 3 years. Swards (initially grass/clover) gave significant increases in total dry‐matter production from regular use of the lowest level of N (26.0 or 34.7 lb N/acre/cut or graze) in 44 out of 49 cases. Extremely high yields were obtained from the heaviest use of N (104.2 lb N/acre/silage cut). 52.1 lb N/acre/cut or graze was the optimum rate of application on ail‐grass and grass/clover swards. Up to about 350 lb N/acre/annum the dosage‐response curve was very nearly straight for all‐grass and grass/clover swards. On the grazed plots herbage left ungrazed amounted on average to only 6% of the total. The health of all stock on the high nitrogen plots (as well as all others

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01176.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Pure swards of S22 Italian ryegrass, H.1 hybrid ryegrass, S170 tall fescue, S48 timothy, S215 meadow fescue and Germinal cocksfoot were each harvested at several stages of maturity during first growth in the spring, and in the subsequent regrowths. Each batch of herbage was fed to sheep in a digestion trial under conditions of voluntary intake. Results from the first growth herbages showed the expected fall in digestibility with increasing maturity. However, the digestibility of S22, H.1, S170 and S48 began to fall well before ear emergence, whereas the digestibility of Germinal fell only slowly up to the time of ear emergence, as had been found previously with S24 and S23 ryegrass and S37 cocksfoot. The rate of fall of digestibility in H.1 and S48 (0.4 units/day) also appeared to be lower than with the perennial ryegrasses and cocksfoot (0.5 units/day). The monthly regrowths within each herbage were of similar digestibility, but the mean digestibility of regrowths differed between herbages, being highest for S215 and lowest for Germinal and S170. The grasses with highest digestibility in the early Spring, in particular S22 ryegrass, were not, however, always the most digestible in the subsequent regrowths. The numbers of sheep fed on each herbage were insufficient to show whether there were significant differences in voluntary intake between different herbage species of the same digestibility. It is suggested that an intake/digestibility relationship, based on data from more animals, should be developed for each herbage species. Only if different relationships are found can it be concluded that factors other than level of digestibility have an effect on intake.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01177.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Assessments of animal preference (measured as mean % herbage removed) were made on varieties of cocksfoot in Yorkshire and in Scotland, and parallel chemical analyses were carried out. A similar range of varieties were examined at progressive stages of spring growth at Cambridge.In vitrodigestibility tests were made also. In the Yorkshire trials, a significant positive relationship was established between soluble carbohydrates and animal preference and a negative correlation between fibre and animal preference. In Scotland, the relationship between soluble carbohydrate and animal preference was less pronounced. Animal preference in the spring was for the early varieties which have thick and succulent stems up to the stage of ear emergence. In the aftermath animal preferences were less marked.In trials at Cambridge, the early varieties, notably Scotia, were higher than the late varieties both in digestibility and in soluble carbohydrates. This tendency was also present in Scotland but was less pronounced.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01178.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The dry‐matter intake of silage was increased when the silage had a higher dry‐matter content and when the time of access to the silage was increased from 3 to 24 h. Concentrate supplementation had a greater influence in depressing the intake of hay than that of silage. Only a small difference was observed in the replacement of hay by concentrates when the concentrates were given with two hays of different dry‐matter digestibility. Concentrates with a relatively high protein content depressed roughage intake to a lesser extent than concentrates with a low protein co

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01179.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Twin steer calves were used to compare the effects of early weaning indoors with those of rearing on the bucket at pasture. Calves born in the autumn and reared indoors joined their twins at pasture when about 6 months old; those born in the spring were approximately 12 months old when turned out.There was little difference between the performance of indoor‐ and outdoor‐ reared calves born in the autumn. Usually, the spring‐born calves indoors were about 150 lb heavier than their twins at 12 months of age. This difference normally disappeared by the end of the grazing season and twins became fit for slaughter at the same time. No difference could be found in carcass conform

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01180.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The effects of sowing from 10 to 50 lb/acre of tall‐fescue seed on plant establishment and on the annual and seasonal distribution of DM yield of tall fescue and its companion grasses were measured through two growing seasons. Increasing the seed rate increased plant numbers per unit area and decreased per cent establishment. Adding Scots timothy as a companion grass depressed both plant number and per cent establishment. S37 cocksfoot and New Zealand perennial ryegrass reduced both still further. Total annual dry‐matter production was relatively unaffected by varying either the seed rate or the companion grass. The contribution of tall fescue to total production was highest when sown alone and was successively reduced by timothy, perennial ryegrass and cocksfoot. When sown alone there were only slight differences in contribution of tall fescue due to seed rate. With any companion grass the contribution from tall fescue increased with increasing seed rate. Early growth was not reduced by modifying seed rate but was reduced by all the companion grasses. It is concluded that increasing the seed rate of tall fescue above 30 lb is not justified, that Scots timothy can be sown at 3 lb/acre with tall fescue without affecting total production or early growth of the mixture, with the advantages of control of unsown species and improved palatability of the herb

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01181.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The water activity of juice available for fermentation, after breakdown of the cell walls during the ensiling of plant material, depends largely on the moisture content of the sample. Water activity increases with moisture content, but probably never becomes so high as seriously to limit lactic‐acid fermentation, although high moisture contents have other detrimental effects. With low moisture contents, the limited availability of the juice rather than its lowered water activity is most probably the factor primarily responsible for poor lactic‐acid product

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01182.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1964.tb01183.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY