摘要:

AbstractGrass swards were cut at intervals of 2, 3, 4, 5, 6 and 8 weeks and received 336 or 673 kg ha−1nitrogen the higher level being applied as a single or as split dressings. Reducing cutting interval from 8 to 2 weeks reduced mean DM yield by 37% from 14·2 to 9·0 t ha−1and digestible DM yield by 24% from 9·4 to 7·2 t ha−1. The response to the extra N at the highest level of application was greatest under the most frequent cutting regimes. Application of N did not affect the digestibility of DM. Results are discussed in relation to the comparative effects of frequency of cutting at different seasons of the year and at different le

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01431.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIn 1972 and 1973 fields of perennial ryegrass in the West of Scotland were surveyed for ryegrass mosaic virus (RMV). Visual determinations of foliar symptoms were made in the field and leaf samples were collected for diagnosis of the virus by electron microscopy and by sap transmission to S22 Italian ryegrass.In 1972, ninety‐eight fields were surveyed and virus‐like symptoms were observed in 59%, but tests showed that only 21% were infected with RMV. In the more extensive 1973 survey, 201 fields selected on a stratified random basis were examined and whilst 45% had virus‐like symptoms only 5% proved to be infected with RMV.Symptoms were most readily seen in fields which had a high percentage of long, lush perennial ryegrass. Analysis of data collected in 1973 on management practices did not reveal any obvious association between the incidence of virus‐like symptoms and the cutting and grazing regimes, the grazing animal used or the level of nitrogen

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01432.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe performance of timothy in mixtures with perennial ryegrass was assessed under a simulated intensive grazing management over two harvest years in 1974–75. Three seed rates of S23 perennial ryegrass were factorially combined with three rates of Scots timothy and compared with pure stands of each grass. All were sown with Huia white clover. When cut six times at monthly intervals and with an annual N input of 350 kg ha−1, there were no significant differences in total DM production in either year. The 2‐year mean DM yield for the nine mixtures and six pure swards was 9·77 t ha−1(range 9·34–10·16). Compared with the pure ryegrass swards, in both years the ryegrass‐timothy mixtures produced earlier spring growth but were significantly lower yielding at the second cut. Over the first five cuts the proptortion of timothy in the three mixtures with 22·4 kg ha−1ryegrass seed averaged 26% in the first year and 37% in the second. Corresponding calculated mean DM yields of timothy were 2·75 and 3·00 t ha−1.It is concluded that an early timothy variety is capable of competing with a late‐heading perennial ryegrass in frequently cut swards managed to simulate intensive grazing. The strong development of timothy in the dry summer of 1975 suggests that in mixtures of late perennial ryegrass varieties, an early variety of timothy should be beneficial for its spring

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01433.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIn field trials in 1971–73, perennial ryegrass cv. S23 and S24 were given up to 200 kg ha−1nitrogen (N) and dry weight, seed yields and seed yield components measured. Optimum levels of applied N ranged from 80 kg ha−1, where livestock had grazed the crop in the establishment year or where residual N levels were about 70 kg ha−1, to 120 kg ha−1where residual N was low. Application of more than 120 kg ha−1did not increase yields further because of increased lodging and increased production of vegetative tillers. Seed set was 37–55% in S24 and 25–29% in S23 and was decre

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01434.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractAn Italian ryegrass (cv. RvP), a tetraploid hybrid ryegrass (Sabrina), and an early heading timothy (Scots), were compared under 3‐cut silage plus aftermath, 5‐cut early bite‐hay‐aftermath and 6‐cut simulated grazing managements over 2 harvest years 1974–75. Annual nitrogen applications totalled 375 kg ha−1N for the silage and grazing systems and 325 kg ha−1for the early bite‐hay‐aftermath treatment.In 1974, the first harvest year, RvP and Sabrina outyielded Scots timothy. In the dry summer of 1975 the drought tolerance and persistency of Sabrina was superior to RvP, but both grasses gave low yields (approx. 10·0 ha−1DM under the conservation managements) and showed a marked fall in production compared with the first year, by RvP of 35% and by Sabrina of 25%. Scots timothy in the second year equalled the ryegrass in total DM yield under the hay management system. Over the 2 years RvP and Sabrina gave similar yields, which were 10% better than Scots timothy, under all managements.RvP and Sabrina are equally suitable for silage production, but second and third silage cuts of RvP require shorter regrowth periods than Sabrina for good quality herbage. Sabrina will also provide le

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01435.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractA field experiment was conducted during the winter seasons of 1972–73 and 1973–74 to study the effects of rates of application (0, 100, 200 kg ha−1) and sources of nitrogen (ammonium sulphate, calcium ammonium nitrate, urea, sulphur‐coated urea and sulpha‐thiazole‐treated urea) on nitrate‐N concentration in oat (Avena sativaL.) forage. N application increased the nitrate‐N concentration, the effects being more marked when the rate was increased from 100 to 200 kg ha−1than when it was raised from 0 to 100 kg ha−1. The highest nitrate‐N concentration in the dry matter (>0·16%) was obtained when calcium ammonium nitrate was applied at 200 kg ha−1N. Sulphur‐coated urea gave the lowest nitrate‐N concentration. In one year treatment of urea with sulphathiazole reduced nitrate‐

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01436.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractFour sheep in a 4 × 4 Latin Square experiment were offeredad libitumgrass meal pellets alone or supplemented with lactic acid at 600, 800 or 1000 mmol per kg dry matter (DM) intake, either mixed into the feed or continuously infused intraruminally for 6‐d periods. When added to the feed lactic acid did not significantly affect DM intake but when infused intraruminally it significantly reduced DM intake especially at the highest rate of infusion.In a second 4 × 4 Latin Square experiment, four sheep were offeredad libitumgrass meal pellets alone or supplemented with lactic acid mixed into the pellets at 900, 1200 and 1500 mmol per kg DM for 15‐d periods. There was a small reduction in intake on the three lactic acid treatments but this was not significant.In a third experiment the effects of intraruminal infusion with lactic acid was studied further with four sheep which received infusions of lactic acid at a fixed daily rate of 40 mmol per kg W−0·75per d or of an equal volume of distilled water for 3‐d periods while being offered grass meal pelletsad libitum. Infusion with lactic acid resulted in reduced DM intake but the effect was less consistent than in Experiment 1.In all three experiments lactic acid supplementation had little effect on the pH and total volatile fatty acid concentrati

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01437.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractDifferences between field temperature and floating temperature during determination offect apparent leof relative water content (RWC). When floating temperature was lower or higher than field temperature, RWC appeared higher or lower, respectively, than when the temperatures were the same. Discrepancies averaged 0·24% RWC per TC temperature difference for wheat and perennial ryegrass, and 0·33% for the less xeromorphic white clover and potato. These averages might reasonably be used in future for correcting values obtained with these or similar specie

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01438.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractPlots of perennial ryegrass were cut in September, October, November and December 1975, and soil surface temperature, leof extension rates, appearance rates and lengths were measured between September 1975 and April 1976.Cutting on progressively later dates in the autumn reduced leof extension rates and leof lengths throughout the following winter and spring, whereas leof appearance rates were reduced for only about 1 month ofter cutting.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01439.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Book reviewed in this article:Diseases of Grasses and Forage Legumes in Ireland. By C. J. O'Rourke.Tropical Pasture and Fodder Plants.By A. V. Bogdan.A Comparison of Yield and Soil Conditions During 20 Years of Grazed Grass and Arable Cropping.By E. A. Garwood, K. C. Tyson and C. R. Clement.Whole Crop Forages. Relationship Between Stage of Growth, Yield and Forage Quality in Small‐Grain Cereals and MaizeBy A. J. Corrall, A. J. Heard, J. S. Fenlon, Cora P. Terry and G. C. Lewi

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01440.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY