摘要:

AbstractAbove ground production of a typicalCortaderia pilosadominant sward in the Falkland Islands was estimated over one growing season by summing significant positive increments in DM production of various sward components and by sequential cutting to ground level. The standing crop was characterized by a high proportion of standing dead matter at all times of the year. Net herbage production was estimated as 2200 kg ha‐1and 1440 kg ha‐1by the ‘difference’ and “sequential culling” techniques, respectively. The pattern of leaf growth was determined on another site by regular linear measurements of a population of physiologically similarC. pilosaleaves. There was very little early season growth and most of the DM was produced in a short period in the middle part of the growing season. The poor early season growth was attributed to adverse climatic conditions. A significant increase in green matter digestibility in October and November was masked by the low digestibility and high contribution to the overall DM by the standing dead component of the herbage.The implications of these findings are briefly discussed in relation to the increased utilization of C. pilosa by improved pasture management, including burning and possibly reseeding areas with improved species. Tissue turnover studies combined with more knowledge of sheep nutrition cycles would enable grazing systems to be developed on a sounder basis than

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01816.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractObservations made between 1980 and 1982 showed that dipterous stem‐borers were more common in grazed than cut swards. The two forms ofOscinellafrit were particularly prevalent in grazed swards butO. vastatorwas more evenly distributed and dominated the larval populations of the cut sward in 1981. The population dynamics of all species were probably affected by the number of days on which weather was suitable for high stem‐borer adult activity. It was also found that stem‐borer larval numbers could expand rapidly after periods suitable for high adult activity even when adult numbers had been low for long periods. Despite low numbers of O. vastator being present in winter 1981, their numbers increased markedly and built up to a large population which peaked in September

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01817.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe effects of three levels of potash, phosphate and lime fertilizers on the yield and mineral content of white clover (Trifolium repens) and on soil nutrient levels were studied in a field experiment over 7 years. The aim of the experiment was to define an optimum fertilizer programme for breeding nurseries and experimental fields.Potash was the main factor limiting production: clover yield was negligible after 2 years where no potassium was applied. Phosphate increased yields after the third year, while liming had no significant effect on clover yield.The soil potassium status improved with the repeated application of potash over the 7–year period, but no consistent pattern was discernible for the phosphate treatments. There was a slight increase in soil pH with liming.Application of phosphate increased the phosphorous content of herbage, but had no effect on other plant constituents for the first 2 years. Subsequent applications increased the calcium and sodium contents. Potash reduced the content of all constituents other than potassium as the treatment levels increased. Lime had little effect on plant constituents other than calciu

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01818.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThis paper describes the derivation of a series of equations for estimating mean grass production on cut swards under different fertilizer nitrogen, soil and climatic regimes. Using data from the National Grassland Manuring Trial GM20 for a late flowering perennial ryegrass, equations have been estimated for the individual cuts. On the basis of data from cutting trials at Hurley, equations for extrapolating yields under cutting strategies with different first cut dates and regrowth intervals have been derived. The resultant model for predicting yields has then been tested against data obtained from two separate cutting trials. Although in individual cases significant differences between predicted and observed mean yields were noticed, in general the predicted yields were a reasonable approximation to observed yields. Comparison of the predicted yields with those derived from an earlier study by the authors indicated an improvement in the accuracy of prediction.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01819.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractPlants of three varieties of Phleum pratense L. from different latitudes (cv. Engmo, 69°N; cv. S48, 52°N; cv. Motim, 52°N) were grown from the five‐leaf stage at 12°C under continuous illumination or 8‐h days at essentially identical daily inputs of radiant energy. The responses to daylength extension (increase in plant dry weight, plant height and leaf dimensions and reduction in the number of tillers per plant and in tissue dry matter content) were common to all three varieties and although the enhancement in plant dry weight and in leaf size was greater in the Engmo plants, this was principally the result of poorer growth and smaller leaf size in 8‐h days. Marked differences between Engmo and the other varieties in the partitioning of dry matter within the plant were the consequence of differences in the rate of reproductive development. For example, compared with S48 and Motim, first spike emergence and 50% anthesis in the Engmo plants were delayed by 22 and 14 days, respectively, and 40% of the Engmo plants did not become reproductive even after 110 days of long‐day treatment. Furthermore, by the time that 50% anthesis of the mainstem spike had been reached by the long‐day plants of each variety, significant differences in tiller numbers and tiller fertility had developed between the varieties from high and lower latitudes. These findings and the results of previous studies of Poa pratensis,Dactylisglomerata and Bromus inermis are discussed in relation to the adaptation of high‐latitude grasses to the Scandinav

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01820.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe coefficients of the dry‐weight‐rank (DWR) method ('t Mannetje&Haydock, 1963) can be predicted from the general occurrence of the geometric series relationship between abundance and rank of species in a pasture using either an estimate of the percentage contribution of the first ranked species, or from the ratio of the contribution of two spec

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01821.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA field experiment with mixed swards of perennial ryegrass and while clover carded out in 1982–83 using small cut plots is described. With perennial ryegrass, lime slightly decreased annual dry matter (DM) production in 1982 (the sowing year) but increased it in 1983 (the first harvest year) by about 1 t ha‐1. Applications of N and P produced small increases in DM in 1982 and greater increases in 1983. In the latter season annual DM production varied from an average of 3·5 to about 10 t ha‐1with 0 or 480 kg N ha‐1applied in three equal‐sized dressings throughout the growing season. Application of 40 kg P ha‐1in 1982 increased DM production by about 2·5 t ha‐1in 1983 but higher rates had little effect. Fifteen mg extractable P kg‐1soil seemed sufficient to support levels of production normally expected from ryegrass pastures in upland Scotland, Applications of K did not affect DM production. N increased tiller weight and sward height of ryegrass; lime and P tended to increase tiller weight but this effect was not statistically significant. Leaf appearance and tiller number were not affected by treatments.The white clover content of the pasture was decreased 10‐fold by application of N and increased by lime and P (1·45 and 1·46‐fold. respectively). The DM response to P was most apparent in limed soil and was also affected by the siting of the plots in the experimental area. Effects of lime and P on growth of white clover were to increase the number of stolon growing points and root nodule numbers per unit area.The results emphasize the importance of lime and P fertilizer for establishment and growth of pasture in this soil and the differences between white clover and ryegrass in t

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01822.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA comparison was made of stocking rates of 4·7, 5·6 and 6·4 cows ha‐1during the first 7 weeks (period 1) of the grazing season. Each group of British Friesian cows was continuously stocked on a day and a night field. In the subsequent periods 2 and 3 (each lasting 7 weeks) the three groups were maintained at the same stocking rate within periods (4·2 and 31 cows ha‐1, respectively). The differential stocking rates were achieved by the addition and removal of cows.The stocking rates applied in period I had no significant effects on milk yield, milk composition, liveweight change or condition score, in any period. Milk production ha‐1over the three periods totalled 12390,13 978 and 14986 kg, and the estimated utilized metabolizable energy totalled 773, 81·5 and 86·6 GJ ha‐1for low, medium and high stocking rates, respectively.Increased stocking rate in period I was associated with a decrease in sward height in periods 1 and 2. This led to an increase in herbage metabolizable energy, and crude protein contents, and to an increase in tiller population density. The lowest stocking rate gave greater live individual tiller weights throughout the experiment and a longer interval between defoliation of individual tillers in period 1.The results indicate that high stocking rates in the spring are not necessarily detrimental to overall summer performance of spring calving dairy cows. However, high stocking rates in the early season ensure a high level of herbage utilization and milk output ha‐1in that period. Although this practice leads to a reduced sward height in mid season, the sward has less rejected area, a higher tiller population density and a higher digestibility than swards stocked a

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01823.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractNutrient losses during the in‐silo period were determined following the ensiling of grass using three differing harvesting systems. The treatments were either (a) harvesting herbage directly by means of a flail harvester (unwilted flail, UF) or (b) pre‐mowing of herbage with a rotary drum mower and lifting using a precision chop forage harvester with wilting (WP) and without wilting (UP). Herbage was harvested and ensiled over the period 26–29 May 1982, and a good fermentation was achieved with all three silages. Losses of dry matter (DM), organic matter (OM) and crude protein (CP) during the in‐silo period were greatest with the UF system, intermediate with the UP system and lowest with the WP system. Gross energy losses followed the same trend with losses (as a percentage of ensiled levels) of 18·6, 9·8 and 4·4% for the UF, UP and WP systems, respectively. Gross energy loss as effluent accounted for 24% and 22% of total gross energy ensiled for the UF and UP treatments. Patterns of effluent flow differed between the two unwilted silages with a higher peak flow rate with the UF material. Total effluent production at 354 ml (kg DM ensiled)‐1was greater for the UF material than for the UP material (288 ml (kg DM ensiled)‐1). Nutrient loss through surface waste was similar for all three silages whereas gross energy losses arising through residual respiration, fermentation and gaseous loss amounted to 149%, 6·7% and 31% of that ensiled for the UF, UP and WP silages, respectively. The results of this study, taken in conjunction with those of an earlier study where field losses were assessed, indicate that recovery of gross energy during silage making was very similar for the UP and WP systems and only marginally greater than that recovered wit

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01824.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect of goat slurry on species composition and herbage production as compared to inorganic fertilizer was studied in a natural grassland dominated by warm and cool season perennial grasses in Macedonia, Greece. Goat slurry was applied in early spring every 1 or 2 years at a rate of 40 t ha‐1being equivalent to about 160 kg N ha‐1and 100 kg, P2O5ha‐1. Inorganic fertilizer was also broadcast in early spring at a rate of 80 kg N ha‐1and 100 kg P2O5ha‐1every 2 years. Measurements of the basal cover of the dominant species or groups of species and herbage yields were taken for 6 years at the end of the growing period in June, while in the seventh year the experiment was grazed with goats. It was found that goat slurry improved species composition more than the inorganic fertilizer by depressing the less palatable warm season grasses and favouring the subdominant cool season grasses and legumes. Goat slurry significantly increased herbage yields in most of the years. It is suggested that the optimum rate of goat slurry is 40 t ha‐1every 2 years as this encourages plants most preferr

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1986.tb01825.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY