ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00493.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00494.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00495.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00496.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00497.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Over 13 years, 12 cwt/ac of ground rock phosphate (29% P2O5) were applied to an old grass sward, either completely in the first year or in equal amounts in each of the first 4 years; alternatively, 18 cwt superphosphate/ac were applied either in 3 equal amounts at 4–yearly intervals, or in equal amounts annually over the first 12 years.In the first year, the larger dressing of superphosphate gave the best response, measured as fresh herbage cut in mid–July each year, but during the next 7 years all methods of application gave similar yields. Dressings of rock phosphate gave progressively poorer response after 7 years and plots so treated were not significantly better than the control in the final year. At the end of the experiment, plots receiving annual applications of superphosphate yielded most herbage and those which had received superphosphate at 4–yearly intervals still showed a significant response. Phosphate in rock phosphate applied as a single dressing was two–thirds as effective over an 8–year period as that in superphosphate applied annually.The small difference over 12 years in phosphate uptake from 3 dressings of superphosphate compared with its equivalent in annual applications suggested that little phosphate fixation was taking place. The fact that a single dressing of rock phosphate was able to maintain yields and phosphate uptake close to that obtained from annual applications over 7 years supports this and suggests that the failure to utilize one third of the phosphate in rock phosphate was mostly due to initial ins

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00498.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Timothy and bromegrass were studied in pure sowings in a glasshouse, and each in a mixture with lucerne, dominated by the grass–fraction in the first crop year, in the field. In the glasshouse both species were cut 3, 5, or 6 times at a 2–in. and 6 times at a 3/4–in. stubble height. In timothy, cutting 6 times gave lower DM but higher protein yields than less frequent cutting. In bromegrass close cutting gave higher DM yields than lax cutting. The following results applied to both species: root weight decreased with increasing severity of defoliation, final tiller density was very low under close cutting, and a complete application of N at the time of sowing was superior to a split application.In the field, the first cut was taken on 5 dates at intervals of 1 week, the second cut 6 or 8 weeks after the first cut, and the third cut 7 weeks after the second cut (for bromegrass mixture only). DM yield was generally the higher the later the first cut was taken and the longer the subsequent rest period. However, the opposite applied for best sustainment of yield. The 1 1/2–in. stubble treatments outyielded the 3 1/2–in. treatments. Generally, production of CP was influenced more by DM yield than by % content. Reduced removal of tiller primordia in the second cut led to higher third–cut yields, but at the cost of total yield. Difficulties in the control of shoot apex removal encountered in both glasshouse and field ar

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00499.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The responses ofPhalaris tuberosaL. to cutting to 1/2‐ and to 3‐in. at 3 levels of nitrogen (0, 23 and 92 lb/ac after each cut) were investigated in two irrigated, small‐plot trials. A technique involving the use of sheet‐iron borders embedded in the soil to contain root systems, irrigation water and fertilizer was developed. The 3‐in. cutting height gave greater dry‐matter yields than J in., the difference reaching significance only with applied N. Plant mortality was significantly greater for the 1/2‐in. cutting height at each N level. N significantly increased DM yield at both cutting heights, the greatest yield being at the higher application rate. Plant mortality at both cutting heights was significantly reduced by applied N. The results are discussed in relation to the most suitable grazing management for sustained growth of irrigatedP

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00500.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

The altitudinal sequence of soils occurs lower on the north than on the south face of the Brecon Beacons where the highest slopes of the north face are occupied by shallow, strongly leached rankers. Except on lower slopes,Vacciniun, CallunaandNardusdominate the flora associated with each soil type. Unlike their distribution elsewhere,RhytidiadelphusandHypnumare associated with gleyed soils. It is suggested that exposure and inaccessibility have limited hill grazing. The vegetation on the peaty gleyed soils is associated elsewhere with drier soils, formerly extensive on the Beacons, and is preserved despite a changing edaphic environment. Some potentially nutritious pastures on the north face are too exposed to be grazed by sheep during winter, butVacciniumpastures on some lower slopes supply useful winter protein.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00501.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Seven species or varieties of grass, and a mixture of 3 of them, were sown in pure swards, treated with 4 levels of nitro‐chalk (0, 17·5, 35, and 70 Ib N/ac/cut) and cut 4 or 5 times each year. Each species and the mixture were also sown with white clover, and the effect of fertilizer N on the yield of N in each grass was compared with the effect of clover on the yield of N harvested from the grass/clover swards.The regression line for response in yield of N with increasing levels of fertilizer N showed slight, but significant, upward curvature. The grasses differed in their uptake of N from the soil, S37 cocksfoot and S48 timothy showing relatively high uptakes, and the ability of each grass to take up fertilizer N was usually related to its uptake of N from the soil. Differences in the yield of dry matter between the species, at a similar level of N, are discussed, and it was concluded that perennial ryegrasses were most efficient andAgrostis tenuiswas least efficient in using the N taken up in the production of DM.In general, there were no significant differences between the yields of N of the grass/clover mixtures; the N yields of the grass components were significantly different and tended to be inversely related to the N yields of clover.Grasses which gave high yields of N with fertilizer were also high yielding when grown in association with clover. Pure grass swards required more than 200 Ib fertilizer N/ac/yr in order to yield the same amount of N as the grass/clover swards. The amount of N estimated to have been derived by grass from clover (indirect effect of clover) increased each year; it was highest with S37 cocksfoot and lowest with Irish perennial ryegrass, averaging 46 and 23 Ib N/ac/yr, respective

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1967.tb00502.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY