摘要:

The effect of 4 or 5 forms of nitrogenous fertilizer on the yield and botanical composition of a perennial ryegrass/white clover sward was examined in 3 different years. The uptake of N by the grass was also estimated. Ammonium nitrate (as Nitro‐Chalk), ammonium sulphate and urea gave similar yield increases, although in one year, when high rainfall followed the application of fertilizer, urea was slightly inferior. Gas liquor gave variable responses in the 3 years. Nitroform, a urea‐formaldehyde, was generally less effective than the other forms of fertilizer. The uptake of N from Nitro‐Chalk, sulphate of ammonia and urea did not vary greatly from year to year although the uptake of soil N by the untreated control did.Response to N in the yield of dry‐matter varied from year to year. This variation was due partly to differences in the amount of clover present and partly to differences in the extent to which N taken up by the grass was used for the synthesis of dry‐matter.The white clover content of the sward was not greatly reduced in spring by the application of the fertilizer, and there were no consistent differences between the effects on clover of the forms of the fertilizer. A reduction was apparent in the summer but not in the autumn.It may be necessary to increase replication above the level of 3 to 6 which is frequently employed in field experiments if more precise quantitative estimates of response and of the relative efficiency of various forms of nitrogenous fertilizer are

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00471.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

In 2 experiments nitrogenous fertilizer was applied at 3 levels (0, 46 and 92 lb N/ac) to a permanent pasture and a ryegrass/clover ley and the swards were harvested before ear emergence and conserved as either artificially dried grass or tetrapod hay. Apparent dry matter digestibility and voluntary food intake of the conserved herbages were measured with sheep.N caused a small but significant depression in apparent DM digestibility but did not affect voluntary food intake. It increased yields of DM and digestible DM significantly.The DM digestibility and voluntary food intake of hay were always significantly lower than those of the corresponding dried grass. Voluntary food intake of all fodders was directly related to herbage digestibility and inversely related to herbage crude fibre content.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00472.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

An experiment is described in which cocksfoot, grown for production of seed, was cut annually for 3 years in either autumn, winter or spring. No significant increases in yield of seed/ac were obtained from any treatment compared with an uncut control, and a cut in late April in one year seriously reduced the yield of seed. Additional N applied after a defoliation in October did not increase the yield of seed compared with that from plots which were cut at the same time but not fertilized. The production of tillers was not affected by cutting on any date. The percentage fertility of tillers was increased by cutting in the first year, when the number of tillers was smallest; the fertility was less consistently affected in the second year, and was generally unaffected in the third year. The weight of seed produced per ear was usually reduced by the cutting treatments. In the third year of the experiment it was shown that the penetration of light to the base of the shoots was increased substantially by defoliation, but it is deduced that maximum interception of light by the whole plant is more important for the production of seed than increasing by cutting that proportion which penetrates to the base of the plant.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00473.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

An experiment is described in which timothy, grown for production of seed, was cut once annually on dates ranging from 23 October to 24 May. New tillers in selected plants were labelled at monthly intervals during autumn and winter for 2 years, to determine the pattern of production of tillers and to assess the reproductive development of categories of tillers. The majority of tillers were produced in autumn, but production was continuous throughout the winter. There was a big increase from the first to the second year in the total number of tillers produced, but neither the pattern nor amount of tiller production was affected by cutting. The%of fertile tillers was highest in the oldest tillers, and was affected little by the increase in the number of tillers from the first to the second year; cutting had little effect on the % fertility except where floral primordia were removed by the cut on 24 May. In all treatments at least 90% of the ears at harvest were produced by tillers initiated the previous autumn. The penetration of light to the base of the plants was increased considerably by cutting, but it is concluded that interception of light by the whole plant is more beneficial than an increase in the penetration of light into the plant and a concomitant reduction in the total interception of light by the plant.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00474.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

About half an acre (0·40 ha) of the salt marsh grassSpartina townsendii(s. l.) was cut from a Bristol Channel marsh using a small tractor modified for use on estuarine marshland. The cut grass was ensiled with molasses in a plastic silo.Chemical analyses were carried out on samples of fresh grass and silage. Silage was fedad libitumto Halfbred × Suffolk wether sheep. Intake, digestibility values and crude protein content were similar to those of medium quality ha

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00475.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

The effects were studied of nitrogen and phosphorus fertilizers on the production of perennial ryegrass at high altitudes in Kenya. N had little influence on production during establishment but increased it markedly during the second and third years. The effect of P was less and was related to the amount of N applied. The response to applied N in terms of dry matter production, and the recovery of the N applied, compared favourably with data from trials elsewhere. It is apparent from the results that temperate grasses can be productive at high altitudes in Kenya and provide a considerable potential for pasture production.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00476.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

As a preliminary step in the development of improved bred varieties an examination has been made of the factors which contribute to the success or failure of white clover (Trifolium repens) in hill land reseeding. Severe restrictions are placed on clover performance and N fixation in many hill areas in Britain by the poor climate, the low pH and exchangeable base status of the soils and the low frequency of effective indigenousRhizobiumstrains.Agronomic solutions to some of these problems exist, but experience in mid‐Wales suggests the need for new bred varieties with improved adaptation to the prevailing conditions, particular attention being directed to the limitation of N fixation by low soil temperatur

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00477.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

An experiment was designed to compare morphological development, light interception and time interval as possible criteria for the defoliation of timothy, brome‐grass and cocksfoot. The morphological criterion included: (a) a first harvest before stem elongation and a second harvest after initiation of axillary bud development at the base of each tiller (b) a harvest immediately after stem elongation. Light was compared on the basis of 95 % and 80 % interception of the incident radiation by the foliage. Two‐, 4‐ and 6‐week intervals were used in the time series. Increased yields of up to 2600 lb DM/ac were obtained in timothy and bromegrass fertilized at 275 lb N/ac/yr when morphological treatment (a) was used in preference to (b); cocksfoot yields were not influenced. The greater the time interval between harvests or the greater the light interception before harvest, the greater was the yield. Advantages and disadvantages of the 3 criteria are di

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00478.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Among the many problems of pasture establishment in Rhodesia, those which appear the most serious are: (a) poor seed germination, leading to patchy and weak seedling growth; (b) erratic rainfall, in which heavy storms are followed by hot, dry periods; (c) soil crusting, which forms a surface layer impenetrable from below by the seedling, and from above by rainwater; (d) weed competition, where rank and copious weed growth suppresses establishment of pasture seedlings. Suggestions are made as to how these problems might be overcome.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00479.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Little is known about the possible differential responses to Nitrogen fertilizer in varieties within grass species. Two trials were conducted to study interactions between varieties and level of N. The dry‐matter yields of 3 varieties of perennial ryegrass were compared in 4 cuts/yr at 3 levels of N fertilizer. Four cocksfoot varieties under the same cutting management were compared at 2 levels of N. In a total of 20 comparisons, the variety effect was significant on 10 occasions, and the N effect significant in all 20 sets of data. The interaction of variety and N level was significant in only one case suggesting that all varieties in each trial responded similarly to increasing levels of N fertilize

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00480.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY