摘要:

ABSTRACTAn experiment was carried out on a grass/white‐clover sward at North Wyke to evaluate the use of mixtures of inorganic and organic nutrient sources to simulate the nutrient effect of animal excreta, both with and without overall PK fertilizer. Grazing with sheep and the return of excreta from caged sheep both increased herbage yields, as did artificial return treatments. Artificial return treatments giving 75% of the nutrient level returned by excreta gave yields comparable with grazing. The effect of the simulated return treatments was not influenced by PK application. Grazing gave a very different botanical composition to that from the treatments in wbich natural or simulated excreta were returned to cut swards.Mixtures simulating excreta may replace the nutrient effect of the grazing animal, but not its physical effect, in some forms of grassland experimentation. They are not recommended for fertilizer trial

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01200.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTExperiments were conducted on ryegrass swards using different amounts of N fertilizer applied as a single early dressing (S) or in repeated applications during the season (R). Over three years, the yield from R was generally higher, but under dry conditions (using plot covers) S gave the greater yield. The latter result is ascribed to the bigb yield obtained from S at the first cut, at which time N uptake was not limited by a lack of soil water.Irrigation at less than the full requirement resulted in lower total yields but it increased water‐use efficiency by up to 70% (R) and 94% (S

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01201.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTA great number of experiments with varying dates of N application to grassland showed that the most suitable time of applying spring N in tbe Netberlaods varies, as a result of weather conditions, from year to year from mid‐February to mid‐April. In such experiments the best time of spring N application, which needs to be known in advance, can only be determined after the grass bas been harvested and weighed. The results of these experiments supported the opinion that the best application date coincides with the banging of grass growth. However, at that time it was not possible clearly to define the begimiing of grass growth.When in 1959 a measuring disc was put into use the beginning of grass growth could be precisely determined and it was then found that the beginning of grass growth was closely correlated to a certain accumulated temperature from 1 Jan. from which the date of the beginning of grass growth can be predicted. This date is the most suitable one for applying spring N to grassl

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01202.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTGrass production was measured at 24 sites in the Strathdon area of West Aberdeenshire. The mean total yields of DM from two cuts taken from unfertilized plots in 1967 and from three cuts taken in 1968 were 3014 and 3864 kgJha, respectively. Yields from soils formed on basic parent material were 30–40% more than yields from soils formed on more acidic material; and well‐managed swards yielded over 40% more than poorly‐managed ones. Aspect did not affect yields significantly, nor did elevation within the range 260–440 m.NItrochalk applied at the rate of 75 kg N/ha in 1968 increased the DM yield by an average of 35% but the efifect of 75 kg P2O5/ha, applied as triple superphosphate, was not significant at the 10% level. The benefits from N declined, wbereas those from P tended to increase, with elevation. There was no significant NP interaction overall, but tbe response from this treatment was better than from N alone on sites with acidic parent material.In 1968, 46% of the total yield was obtained by the end of June and only 10% after the end of August. Whereas yield declined with elevation in May–June, it increased during J

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01203.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTThree grass silages, all made in mid‐Jnne from the same herbage, were compared in a 12‐week winter‐feeding experiment with 12 Ayrshire cows. The silages were fedad lib. witha supplement of moist barley and gronndnut cake. Silage A was made from unwilted berbage with no additive, silage B from identical berbage treated with 1/2 gal of formic acidJton (2.24 L/tonne) of berbage, and silage C from the herbage after wilting for 28 b. the DM contents of silages A, B and C were 20.5, 21.1 and 31.8%, respectively, and the contents of digestible organic matter in the DM were 58.9, 68.8 and 67.8%. Silage and total DM intake were bigbest on the treatment containing silage B. the mean dafly milk yields on the treatments with sflages A, B and C were 35.1, 38.0 and 34.3 Ib (15.9, 17.2 and 15.6 kg), respectively and the solids‐not‐fat (S.N.F.) contents of the milk averaged 8.53, 8.54 and 8.50%. It is concluded tbat silage B, the unwilted silage with formic‐acid additive, was superior to botb the untreated and the wilted silage as a feed for

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01204.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTAn experiment was set up to measure the production from donally propagated micro‐swards of four contrasting ryegrass genotypes, grown in monocultures and in all possible combinations of mixed cultures consisting of two, three and all four genotypes. Water and nutrients were supplied frequently in non‐limiting quantities and the swards were subjected to two cutting frequencies.The yield ranking of the monocultures and mixed cultures diifered at the two cutting frequencies. Under infrequent cutting, though not under frequent cutting, two mixtures, each containing two genotypes, were more productive than their highest yielding components in monoculture. The physiological basis of this apparent synergy is hriefly discussed and it is suggested that the increased yield may he due to more efficient light utilization hy the mixtures. In general, yields of other mixtures, including those consisting of 3 or 4 genotypes were intermediate between the highest and lowest yielding components in monoculture.The agronomic and plant‐breeding implications of the results are disc

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01205.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTThe N content of pasture species (Trifolium repensL. andLolium perenneL.) was much less affected hy drying temperatures over the range 70° to 100°C, and hy the density of packing of the pasture sample, than was the amount of hrown colour resulting from these treatments. The DM content of faeces was measured with equal accuracy at temperatures of 80° and 100°C and in samples which varied in weight over a four‐fold range. The N lost while drying faeces at 80°C was considerable, with large variations in the amount lost by different animal species fed on particular diets. The results confirm that analyses of the N content of faeces should be carried out before

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01206.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTPlant DM production from naturalNardusandFestuca–Agrostispastures under two cutting regimes ranged from 1023 to 2265 kg/ha. The amounts of mineral N and P produced during the incubation of these plant materials, and from sheep faeces derived from them, were measured under a range of temperature and moisture conditions. These amounts, together with the N liberated in urine, and the increase in inorganic P concentration which resulted from the conversion of feed to faeces, were used to calculate the range in ‘potentially available’ plant nutrients derived from decomposition pathways in the presence and absence of sheep. Factors which infiuence the actual availability of nutrients for plant growth are considered and the results discussed in relation to the role of the grazing animal in the soil‐plant–aaimal nutri

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01207.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTResidual response to an initial application of nitrogen was measured in 3 years and was found to be quite large, e.g. a response of 8 Ib DM per extra Ib N at the first harvest, when applying 125 Ib N/ac (140 kg/ha) rather than‘75 Ib (84 kg/ha) and allowing 6 weeks' growth, was increased to 21 Ib DM when yield from residual cuts was taken into account. Response was large in relation to the amount of N estimated to have been left behind after the first harvest. Marginal recovery of N, already quite high at the first harvest, was increased to a little over 90% when yield from residual cuts was taken into account Recovery, however, was lower than this when 10 weeks' growth was allowed before the first harvest, and it seems that, in this case, some N may have been lost from the system. A supplementary experiment suggested that the residual effect of N on DM yield could be obscured to some extent by fresh applications of

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01208.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTFour varieties of perennial ryegrass, (S24, S321, S23 and Endura), were grown in monoculture and in all possible binary mixtures. Three spatial arrangements of varieties within mixtures were used. Total DM yields were recorded from nine harvests during 1969 for mooocultures and mixtures and for the mixture components.The arrangement of varieties within mixtures had no effect on the total DM yield of the mixtures. Monocultures and mixtures did not differ significantly in yield at any harvest or in annual total, bnt there were differences between monocultures at some harvests. No differences between mixtures were detected.The experiment took the form of a competition diallel in which monocultures corresponded to the parents in a genetic diallel and mixtures to the crosses between these parents. There was a significant interaction hetween the rows (i.e. main variety effects) and the columns (i.e. associated variety effects) of the diallel table only at the first harvest. The change in the competitive ability of the four varieties throughout the season was examined. The relative ranking order of varieties for competitive ability altered as the season progressed.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1970.tb01209.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY