摘要:

The response of clover‐free grass swards to fertilizer N when cut repeatedly at grazing and silage stages of growth was measured in four experiments at North Wyke. There was variation between years in the yield obtained at a given fertilizer N rate (Fn) and this was attributable to differences in soil‐N supply. By estimating soil‐N supply from the N‐yield of the non‐fertilized plots (Zn), total N inputs (Tn) were assessed. Over a number of reported experiments it was found that grass‐N yield (Gn) was related to Tn by the equation Gn=0.57 Tn, where Tn=Fn+l.7 Zn. The level of grass‐DM yield depended on stage of growth at cutting, as well as on total N supply. These results, and others examined from the literature, suggest that while total N input is the main determinant of grass‐DM yield, account must be taken of the time available, before defoliation, for the N taken up to be utilized in DM production. The use of Tn values has allowed the collating of N responses obtained over a range of sites, seas

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01051.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Pure stands of S24 ryegrass and S37 cocksfoot were grazed by groups of 6–8 cows for 5 periods spread over 3 years. Three periods were in the spring and two in the summer. The ryegrass was 4–5 percentage units more digestible than the cocksfoot and generally contained more soluble carbohydrate. In the spring periods, the organic‐matter intakes and milk yields of the cows were much the same for the two herbage species, but in the summer they were both higher for the ryegrass. There were no important differences in milk composition due to herbage species, or in the liveweight changes of the

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01052.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Seed of S24 perennial ryegrass of two weight ranges, 0.9–2.1 and 2.5–3.6 mg, were sown in soil at depths of 1.25, 2.5, 5.0 and 7.5 cm. Seedling growth was studied during the 3 weeks following germination.Seeds of both weight ranges germinated equally well at soil depths down to 7.5 cm. However, the number of shoots that emerged was reduced as the sowing depth increased. At similar depths of sowing, seedlings from the heavy seed were heavier and developed more leaves and tillers than those from light seed. Deeper sowing reduced seedling weight and the rate of leaf‐ and tiller‐production. After emergence, the relative growth rates of the seedlings which grew from seed of both weight ranges were similar at those depths of sowing which permitted the highest proportion of emerged shoots to seeds sown. This indicates that the weight advantage gained by the seedlings that developed from heavy seed during their non‐photosynthetic stage of growth was maintained, and was not increased by a greater relative growth rate after photosynthesis began.The implications of the findings are discussed in relation to plant breeding, commercial seed production and sward esta

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01053.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

The annual yield of tall fescue was higher than that of Italian ryegrass in the third year after sowing, but the total yield of herbage from grass plus clover swards was similar.In both the second and third year after sowing, the yield of herbage in the spring grazing was higher when fescue was used as the sown grass. The method of establishment of both tall fescue and Italian ryegrass affected the total and seasonal yield in the second and third year after sowing, but the magnitude of these effects was not nearly as marked as it was earlier in the life of the leys. In the second year after sowing, swards of both Italian ryegrass and tall fescue had a higher yield of total herbage and of white clover, and a lower ingress of unsown species, when established without a cover crop and grazed frequently in the year of sowing.The inclusion of red clover did not increase total yield of DM in the second and third year after sowing, and it slightly decreased the yield of the tall fescue mixture in the third year following sowing when N was applied. S170 tall fescue was readily grazed by sheep in spring and autumn.The apparent recovery of applied N varied with the mixture sown, and the management given during establishment.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01054.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

The effect of partial evacuation of air from polyethylene containers, at the time of sealing, on the chemical composition and nutritive value of silage was determined. Four containers of 500‐kg capacity were filled with herbage harvested from each of four swards, namely, S170 tall fescue, Syn I tall fescue, Tetila Tetrone Italian ryegrass and an S24 perennial ryegrass/S100 white‐clover mixture. All the containers were sealed immediately after filling and half of them were evacuated. The silages resulting from these treatments were offeredad lib.to store sheep and the intake and digestibility of the dry matter determined. The evacuation of the silos had no significant effect upon the chemical composition of the silage produced. The intake and digestibility of the dry matter in the silages were not significantly influenced by evacuat

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01055.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Two experiments were carried out to measure the yield, canopy structure and light interception of S23 and Ba 6280 perennial ryegrass in monoculture and mixed culture. The mixed culture outyielded both monocultures only under frequent cutting and a high fertilizer regime. Measurements of canopy structure and light profiles within the canopies under these latter treatments indicated that the greater residual leaf area after defoliation in S23 and in the mixture may have resulted in their superior production compared with Ba 6280. The fact that a greater percentage of the intercepted light energy was distributed over the most photosynthetically efficient tissue may explain the higher production of the mixture when compared with S23 in monoculture.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01056.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

During June to September 1966 grazing activities of four randomly selected individuals in a herd of 17 non‐lactating, free‐ranging cattle were observed on an Irish hill‐farm of approximately 15 hectares which provided a choice of four distinct vegetative associations. A marked preference forHolcus‐Poa‐Anthoxanthum‐Agrostissward was noted. Grazing did not take place at night. During daylight it occupied three distinct periods, ceasing shortly after sunset and beginn

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01057.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

The summer‐donnancy period among collections ofPhalaris tuberosaL. from the eastern Mediterranean region when grown at Davis, California, ranged from 30 to 127 days. Plants from the more arid sites of origin tended to exhibit the longer dormancy. There were exceptions, however, and these, together with the diversity of behaviour in this material, suggest that genotypes with a potential for increased summer growth may be selected for use on rangeland

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01058.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

This experiment confirmed earlier experience that dalapon applied at doses between 2 and 5 lb a.e./ac (2.242 and 5.605 kg/ha) in early July can suppressAgrostis stoloniferaandHolcus lanatusgrowing in perennial ryegrass pasture. The long‐term control ofPoa trivialiswas not achieved, partly because of a widespread emergence of seedlings shortly after spraying. Dalapon caused a reduction in the total herbage harvested diuring the 14 weeks after spraying, but the yield subsequently increased above that of the unsprayed sward. A substantial increase in the yield of ryegrass occurred. Nitrogen caused a general increase in the yield of herbage and the proportion of ryegrass, but neither N nor dalapon used alone was as efficient in improving yield as their use in combination. Treatment with dalapon resulted in an increase in the number of ryegrass tillers per unit area in the April following spraying, as well as in the yield and ground cover of this specie

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01059.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

The eflFects of various systems of winter‐grazing management on pasture production in the following spring and summer were studied in four trials in the Pentland Hills, Scotland. Winter grazing reduced the yield of herbage in spring, but growth in May and June was primarily influenced by the level of nitrogen application in spring, irrespective of winter‐grazing treatme

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1969.tb01060.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY