摘要:

ABSTRACTThe importance of predicting grass N yield lies in its controlling influence on grass DM output and thus on animal production. Results from 88 experiments studying the use of fertilizer N on cut grass swards show that the major part (97%) of the variation in grass N yield could be explained in terms of fertilizer N rate, an estimate of soil N and an interaction between the two. From this, it appears that high fertilizer N recovery is associated with a high uptake of soil N and vice versa.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00638.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

ABSTRACTTwo successive grazing experiments were conducted over 12 weeks on perennial ryegrass pastures with 50 and 44 young cattle to study the effect of N fertilizer when applied at a daily rate of 1 or 3 kg N/ha. At each level of N two stocking rates differing hy 20% were imposed. At the liigher N level and stocking rate, three frequencies of grazing were imposed.At the stocking rates imposed N tended to reduce the daily liveweight gain per head, but increased the total liveweight gain per ha by from 0.79 to 1.58 kg/kg N. A 20% increase in stocking rate depressed gain per head in both years. In the first year it did not improve gain/ha, hut in the second year gain/ha was increased by 12–17%.There was a tendency for performance per animal and per ha to increase as the grazing cycle was lengthened. In 1969 the highest yield in the whole season was 1880 grazing days and 1260 kg gain/ha.The overall response to N fertilizer was similar to that recorded in other reports, but it is possible that a lack of K had limited pasture growt

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00639.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

ABSTRACTNet photosynthesis per unit area of ground surface was determined at saturating light energy levels inDactylis glonwrataswards over a wide range of leaf area indices (LAI). The relationship between net photosynthesis and LAI was influenced by the particular defoliation regime to which the sward was subjected. In most instances net photosynthesis and LAI were linearly related, with defoliation regime influencing both the slope and intercept of the regression. However, a defoliation regime which left leaves below 3 inches (7.5 cm) resulted in a curvilinear relation. The net photosynthesis‐LAI relationships were compared with the DM production of the swards on which they were obtained. Differences in these relationships did not entirely explain the differences in sward yield. The significance of these findings is discussed with reference to the theories of light interception and pasture growt

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00640.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

ABSTRACTAlfalfa leaf‐cutter (Megachile rotundataF.) bees were used to pollinate lucerne plants in glasshouse compartments. This method was particularly useful in a plant–breeding programme where rapid multiplication was required.Apparatus is described and some results are presen

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00641.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

ABSTRACTEstimates of forage production and consumption were made, using dry‐weight differences between samples from protected and grazed areas. Two sizes of cage for protecting areas from grazing were compared in four forages: brome grass (Bromus inermisLeyss.)/Iucerne (Medicago sativaL.); crested wbeatgrass (Agropyron crista‐tumL.)/lucerne; intermediate wbeatgrass (A. intermedium(Host.) Beauv.)/Iucerne; and Russian wild‐rye (Elymus junceusFisch.).Production, over a three‐year period, ranged from 1985 to 6286 kg/ha when estimated from 0.84 m2cages. Consumption ranged from 1584 to 5878 kg/ha. Yield estimates wben using 2.51 m2cages averaged 8% less than estimates from 0.84 m2cages.The number of caged sites needed in each plot to estimate a 95% confidence interval for annual production were 14 for four replicates, and over 30 for fewer replicates. Requirements for consumption estimates were similar. To estimate production within a 90% confidence interval 19, 10 and 4 caged sites were required from two, three, and four replicates, respectively. Consumption estimates within tbis confidence interval required 22, 10, and 5 samples from two, tbree, and four replicates, respectively.Caging requirements were tbe same for all combinations of plot size and forage species. Large cages increased precision sligbtly wben used on Russian wild‐rye, probably because the forage was in rows 0.9

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00642.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

ABSTRACTThe construction and use of a lightweight plastic harness for total faecal collection from young male lambs and wethers is described. The presence of this harness does not appear to interfere with growth and normal behaviour; it is therefore suitable for indoor‐ and‐field experime

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00643.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00644.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00645.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00646.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1971.tb00647.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY