摘要:

AbstractThe influence of N in slurry or in mineral fertilizers on herbage yield and nitrogen fixation by white clover grown in mixed swards was investigated. Two levels of N in cattle slurry were compared with a range of mineral N fertilization. The percentage of N derived from symbiosis (% Nsym) was measured by the15N‐isotope dilution method. The measurements were made in spring 1987 in two 4‐year‐old field trials, and included two out of five harvests.The % Nsymwas approximately 90% without N fertilization. It decreased in response to both mineral N and N in slurry but did not fall below 63%. The sum of two harvests revealed that 51·2 kg N ha−1were fixed in the absence of N fertilization. With 75 kg mineral N ha−1or 50 m3cattle slurry ha−1, the yield of fixed N decreased to 17·2 and 24·9 kg ha−1, respectively. When compared on the basis of the fertilizer effect on dry matter yield and N concentration of perennial ryegrass, the decrease in yield of N fixed due to treatment with cattle slurry was less than that due to mineral N fertilizer. This was owing to the smaller extent of the depression in the proportion of white clover in the sward when the same amount of N was applied in cattle slurry, as compared with mineral fertilizer, although % Nsymresponded similarly to both types of

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb02186.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractIn each year from 1984‐5 to 1987‐8 the effect of leatherjackets on yield of improved upland pasture was assessed at Redesdale Experimental Husbandry Farm in Northumberland. Chlor‐pyrifos at 0.72 kg ha−1was applied in November or December to half the plots; these and the untreated plots received one of four fertilizer rates (0, 40, 80, 120 kg N ha−1). All rates increased yield by a mean of about 24 kg DM kg N−1.There was a significant correlation (Y (t DM ha−1) = 0‐21 + 0‐00168 ×, r = 0‐99 (P= 0.001)) between yield response to chlorpyrifos and leatherjacket numbers m−2in November/ December. Treatment thresholds for leatherja

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb02187.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractOver a 24‐week period during the 1986 summer, three groups of January‐ to March‐calving dairy cows were either grazed conventionally (G) or grazed between morning and afternoon milkings and housed overnight and offered grass silage (Si) or a straw/concentrate mixture (St)ad libitum.The straw/concentrate mixture contained proportionately, 0‐33 long barley straw, 0·28 ground barley, 0·12 soya bean meal, 0·25 molaferm and 0·22 minerals. The metabolizable energy (ME) and crude protein (CP) contents of the silage fed in weeks 1‐8 and weeks 9‐24 were 9‐5 and 10−6MJ kg MD−1and 160 and 191 g kg DM−1respectively. The straw mix had an ME content of 10−1MJ kg DM−1and CP content of 134 g kg DM−1. Partial storage feeding with silage or a straw/concentrate mixture led to a decrease in estimated herbage DM intake. The feeding of the straw/concentrate mixture increased total DM intake, but the estimated total ME intake was similar for treatments G and St. The intakes (kg DM d−1) for treatments G, Si and St were respectively, herbage 11·7,6·8,4·1; total l3·5,13·6,15·0; total ME intake (MJd−1) 163, 155, 163.Animal performance was, for treatments G, Si and St respectively: milk yield (kg d−1) 19·2, 17·5, 19·1 (s.e.d. 0‐87); milk fat content (g kg−1) 36·9, 37·6, 37.1 (s.e.d. 1.22); milk prote

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb02188.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractIn a pot experiment the pH of a hill peaty soil was adjusted to cover the range 3.8 to 6.8 with Ca(OH)2. Yield and N content of the harvested plant material was greatest at pH 6.8 in pots sown with onlyLolium perenne, and greatest at soil pH 6.1 in pots sown withTrifolium repensandL. perenne. T. repensestablished only at soil pH between 4·3 and 6·1. A small reduction in sward yield and a large and highly significant decrease in total N recovered by the harvested material, which occurred with increase in soil pH from 3·8 to 4·3, was attributed to a combination of increased N immobilization in the soil microbial biomass and to the poor performance of both sown and self‐propagating indigenous species around p

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb02189.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractPlots of an established perennial ryegrass sward (cv. Talbot) fertilized with 100 or 300 kg N ha−1were harvested with one of three plot mowers; an Agria with 38‐mm finger spacing and an Allen Mayfield with 38‐mm finger spacing or 78‐mm finger spacing. The choice of mower was arranged factorially with four post‐harvest treatments: no post treatment; a second (cleaning) cut using the same mower and cutting in the same direction as the first (sampling) cut; a cleaning cut using the same mower, but in the opposite direction to the sampling cut; and a cleaning cut using a rotary mower. Sward productivity as organic matter (OM) was measured over four harvests at 6‐ to 7‐week intervals. The Agria mower resulted in 12·3 and 15‐9% more OM yield than the Allen Mayfield fitted either with knife‐bars at a similar spacing, or with wider‐spaced fingers, respectively. Yield of OM in the subsequent cut was reduced when a cleaning cut was taken; particularly when it was taken in the opposite direction to the sampling cut or when

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb02190.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Land Use and the European Environment Edited by M. Whitby and J. Ollerenshaw

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1990.tb02191.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY