bluuebunny/crossref_metadata_2025_split huggingface dataset:
Yield response of improved upland pasture to the control of leatherjackets under increasing rates of nitrogen
Authors: FRENCH N. , NICHOLS D. B. R. , WRIGHT A. J. 
Published: April 2006

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−1 was 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−2 in November/ December. Treatment thresholds for leatherjacket numbers are given.
The influence of the carbohydrate fraction and additives on silage quality
Authors: PETTERSSON K. LUNDÉN , LINDGREN S. 
Published: April 2006

AbstractRespiration losses, effect of sugar content, formic acid addition and inoculation were evaluated in relation to initial fermentation and silage quality in three experiments. Changes in the content of fermentable substrate during post–harvest respiration and initial fermentation were studied in the laboratory. Soluble carbohydrates were estimated as glucose, fructose, sucrose, fructans and starch by an enzymatic method.About 70% of the sugars remained after 30 h of conventional wilting, as opposed to less than 50% in a chopped sample kept in the dark. During the first days of fermentation the metabolic activity was very intensive. Sugars, which accounted for 10% of the dry matter, were fermented within 4 d. There were indications, mainly in clover silages, that substances other than water‐soluble carbohydrates were used as energy sources.Low‐sugar crops were obtained by shading the fields. After 3 d the sugar in the grass had decreased to half of the original content. This effect was less pronounced in clover. The amount of available substrate and dry matter (DM) content had a major influence on silage quality. In an unwilted crop at least 25 g of water‐soluble carbohydrate was needed per kg of fresh material to obtain an acceptable silage quality in the controls, while 20 g was sufficient in inoculated silage. Formic acid addition makes the fermentation less sensitive to water–soluble carbohydrate content. Inoculation of willed silage increased lactic acid production and decreased the pH. There was also less variation in silage quality.
The effects of contrasting cutting regimes on the components of clover and grass growth in microswards
Authors: GRANT SHEILA A. , BARTHRAM G. T. 
Published: April 2006

AbstractMicroswards of white clover and perennial ryegrass were subjected to one of four treatments: weekly cutting to 3·5 cm, weekly cutting incorporating a period of no cutting for 6 weeks starting 27 April (early rest), weekly cutting incorporating a period of no cutting for 6 weeks starting 8 June (late rest), or cutting every 3 weeks. Two sward types were used: a mixture of white clover cv. Milkanova with perennial ryegrass cv. Melle, and white clover cv. Kent with perennial ryegrass cv. Melle. Growth measurements (leaf appearance, branching/tillering and stolon internode length) were confined to the first three treatments with records collected during contiguous 21‐d measurement periods. Vertical height increments of clover and grass and red:far‐red light ratios at the sward bases were also recorded at frequent intervals. At the end of the experiment population densities and unit weights were recorded for all treatments.Significant treatment effects on the rate processes were largely confined to the 21‐d period immediately after weekly cutting of rested swards had resumed. On previously rested compared with weekly cut swards, clover leaf appearance rates were increased by 40% and branching rates by 164%. During the same period, grass leaf appearance rates were reduced by 50% and net tillering changed from positive to negative values. Though the rate responses were transient, effects were still apparent at harvest in September, when population density and content (proportion by population density and weight) of clover were significantly higher in the late rest treatment. The variety Kent showed a consistent, though usually nonsignificant, higher leaf appearance and branching rate compared with Milkanova, and in September was characterized by a higher population (7400 m−2 compared to 3200 m−2) of smaller units (27 compared to 46 mg/apical meristem) than Milkanova.The results are discussed in relation to defoliation effects and the role of light quantity and quality as they influence the component growth processes. Attention is drawn to the importance of canopy structure and the climatic and/or phenological differences in the relative seasonal behaviour of clover and grass, together with varietal variation within species in influencing responses to management manipulations.
The relationships between stolon characteristics, winter survival and annual yields in white clover (Trifolium repens L.)
Authors: COLLINS ROSEMARY P. , GLENDINING MARGARET J. , RHODES I. 
Published: April 2006

AbstractFive white clover populations of Swiss origin and three bred varieties were grown in binary mixtures with two perennial ryegrass varieties, Aurora and S23. The seasonal yields of clover and grass plus clover were measured under a cutting regime during the second and third years after establishment. A series of destructive detailed sward measurements was made during the late autumn to spring period preceding each harvest year. In this way changes in the amounts of stolon, leaf plus petiole and numbers of growing points were monitored during the winter.There were large differences in clover yield between populations in both years. These were evident from the first (spring) harvest in each year. Higher‐yielding clovers in spring tended to produce higher annual clover yields. No grass × clover interaction was evident at any harvest. Large differences between clovers were also apparent in the morphological characteristics measured, with the Swiss material generally having greater amounts of stolon, leaf plus petiole and numbers of growing points present in early spring. It is proposed that these factors contribute to the high spring yield in the Swiss populations. Loss of stolon length over each winter was less in the Swiss material, indicating that its good spring growth was not obtained at the expense of winter hardiness. Annual clover yield was found to be significantly positively correlated with the amount of stolon present in spring, exemplifying the importance of stolon survival over the winter.
Response to late season nitrogen of upland swards in Wales
Authors: SKINNER R. J. , ALLEN J. W. 
Published: April 2006

AbstractDuring 1984 and 1985, trials at sixteen sites throughout Wales measured the yield response in upland swards from applying 40 and 80 kg N ha−1 at three dates, 20 August, 4 September and 18 September. All sites were between 230 m and 345 m above sea level. Grass yields were measured by cutting plots during October and November.Nitrogen increased the herbage dry‐matter (DM) yield at all sites in both years. The yield response per kg N applied varied between sites. Mean yield response for the two years declined from 16·2 kg DM kg N−1 with 40 kg N ha−1 applied on 20 August to 8·9 kg DM kg N−1 with 80 kg N ha−1 applied on 18 September. In general there was a decline in response to N with increased rate and delay in time of application. The results indicate that responses above an optimum of 9 kg DM kg N−1 can be obtained well into September. A general rule that 1 kg N can be economically applied per 4 summed day degrees air temperature >6 °C remaining in the autumn up to 30 November is suggested.Delay in application and increasing N rate increased crude protein in the herbage but had only small effects on modified acid detergent (MAD) fibre and sugar. Generally, grass quality was good. Sward density assessed during the spring after nitrogen had been applied appeared to have been unaffected by the treatments.
A model of aerobic fungal growth in silage.
Authors: PITT R. E. , MUCK R. E. , PICKERING N. B. 
Published: April 2006

AbstractA simulation model of yeast and mould growth in aerobically deteriorating silage was tested and analysed. The model predictions of aerobic stability were compared with actual stability data from published experiments and were accurate when maize silage composition and initial yeast and mould counts were known. The time‐course of deterioration was simulated for various initial temperatures and yeast and mould concentrations and exhibited primary, secondary, and tertiary heating in some cases; however, the model was limited in its ability to predict temperature history during deterioration because of the simplified treatment of heat transfer. In simulations, the relative importance of yeasts and moulds depended mainly on initial fungal concentrations, whereas the relative importance of mesophiles and thermophiles depended primarily on initial temperature. The model predicted that the period of silage aerobic stability ends when fungal concentrations reach approximately 0·001 g g−1 silage. Temperature, water‐soluble carbohydrate concentration, fungal populations, and fermentation product concentrations in interaction with pH had the greatest direct effects on predicted aerobic stability. The model results suggest that aerobic stability is greatest when the pre‐ensiling forage is highly buffered, of low dry matter content, and contains sufficient water‐soluble carbohydrates to allow fermentation to the lowest possible pH with no residual water‐soluble carbohydrates.
Effect of winter grazing date on yield components of Lolium perenne (L.)/Trifolium repens (L.) hill pasture
Authors: Jaindl R. G. , Sharrow S. H. , Meyer H. H. 
Published: April 2006

AbstractPerennial ryegrass/white clover pastures were grazed at different times in the winter to study the effect of time of grazing on subsequent plant growth. In 1983–84, 1984–85, and 1985–86, pastures were grazed to a residual of 400 kg dry matter ha‐1 by sheep once in early December (D), January (J), February (F), March (M), or April (A) and compared with an ungrazed control (C). Rates of herbage accumulation on C in the winter were low, averaging 6, ‐9, and 2 kg dry matter ha‐1 in December, January, and February, respectively. Little forage production occurred during the month immediately following winter grazing. Herbage accumulation rate then increased sufficiently to replace the forage removed from winter‐grazed paddocks by early spring. By May, herbage mass on grazed treatments was similar to C except for D and A which averaged 20 and 47% less forage than C, respectively (P<0·01). Herbage accumulation rates of D were unique among winter grazing treatments in never exceeding those of C. By May 1986, D yielded less perennial ryegrass compared with C (P<0·05). Grazing reduced the number of leaves per ryegrass tiller for 1 to 2 months following grazing. By May, J, F and M had numerically more tillers m‐2 and more leaves per tiller than C. Similar May yields of J, F, M, and C resulted from fewer but larger and slightly less leafy tillers of ungrazed compared with winter grazed plants.
The effect of glucose oxidase on the preservation of grass silage
Authors: Rauramaa A. L. , Setälä J. J. , Tommila A. E. A. 
Published: April 2006

AbstractFive experiments were carried out to investigate the effects of glucose oxidase (GO) on the preservation of grass silage in the absence of micro‐organisms. In the first experiment, GO was tested in a 3% glucose solution. At the level of 1190 U GO l‐1 the pH value decreased to 3·94 in 1 h and to 3·02 in 24 h. At the level of 11·9 U l‐1 the pH decreased to 3·45 in 24 h.The second experiment was performed by packing chopped grass into glass jars, sterilizing in an autoclave and adding GO. One day later the pH value had decreased to 4·65; 1·60% gluconic acid was found in the dry matter.In the other three experiments grass was sealed in polythene bags and sterilized by gamma‐irradiation. GO was found to cause a faster decrease in pH. Removing air from the silage by compaction decreased the GO activity. The addition of cellulase delayed the GO functioning for one day. Lactobacillus inoculant had no effect. Evidence was obtained that GO may affect the profile or activity of the original microflora of grass silage.
Potential impacts of climate change on patterns of production and the role of drainage in grassland
Authors: ARMSTRONG A.C. , CASTLE D.A. 
Published: April 2006

AbstractGrass production can be predicted using a simple model whose inputs include daily meteorological variables. Changes in both daily temperature and the soil water balance can be expected as a consequence of anthropogenic increases in the CO2 content of the atmosphere. Possible consequences of such changes for grass production are then predicted using the model. These indicate that, for the UK, patterns of grass production could be shifted significantly. Greater grass growth in the spring would follow from the increase in temperature, particularly on drained land where growth is not constrained by water logging. However, grass growth would be depressed by the mid‐season soil moisture deficit, and this again is more marked on drained land, it is concluded that, under a changed climate, the drainage of grassland to enable early season access to the land, together with sound management to optimize output, will be even more important than at present.
Factors affecting sonic sward stick measurements: the effect of different leaf characteristics and the area of sward sampled
Authors: HUTCHINGS N. J. 
Published: April 2006

AbstractLaboratory experimentation found smooth and pubescent leaf surfaces to behave as specular (mirror‐like) reflectors of ultrasound, whilst ribbed leaves behaved as an array of reflectors. It was concluded that swards composed of species with smooth, erectophile leaves would reflect ultrasound poorly and that this may explain the low sward height measurements returned by the sonic sward stick in the field when compared with the HFRO sward stick. The likely effect of species with planophile leaves such as clover is discussed. The sward surface influencing a sonic sward stick measurement was calculated to subtend a solid angle of about 43° at the transducer, equivalent to an area of about 1000 cm2 with the transducer mounted at a height of 50 cm. However, measurements made over turves of varying sizes or over turves with cores of varying size removed found the sensitivity decreased very rapidly beyond an inner area subtending a solid angle of about 7° this is equivalent to an area of about 30 cm2.
Out‐of‐season management of grass/clover swards to manipulate clover content
Authors: LAIDLAW A. S. , TEUBER N. G. , WITHERS J. A. 
Published: April 2006

AbstractTwo experiments are described in which the effect of grazing or defoliating mixed swards at different times over winter and spring on clover content and development was investigated.In the first experiment swards were grazed with sheep (to about 3 cm) for a short period in (a) November, (b) November, January and March, (c) March or (d) not at all, in three consecutive years. All swards were grazed intermittently during the grazing season with cattle and cut for silage once each year. Each plot received either 0 or 50 kg N ha−1 in March.The effect of N fertilizer was to reduce clover content in each summer and clover growing point density in the third year.In two of the three years, treatments involving grazing in March had lower subsequent net annual herbage accumulation compared with the other two treatments and higher clover content in summer of the third year. Reduction in growing point density in all plots during the grazing season was associated with cattle grazing when conditions were wet, suggesting that stolon burial was implicated. Grazing with sheep in November, January and March resulted in significantly more visible (when counted in situ) clover growing points in April in year 2 and more total growing points (counted after dissection of turves) in the third year than the November grazed and ungrazed treatments which had, on occasions, higher grass tiller density.In a microplot experiment, high herbage mass standing over winter was associated with lower potential photosynthesis per unit clover lamina area and lower growing point density in March. Cutting herbage in March to 2‐3 cm resulted in higher clover content and higher growing point number per unit stolon length. The latter was significantly correlated with total irradiance and red: far red at the canopy base. Potential photosynthesis of clover was not affected by cutting in March.It is concluded that growing point density can be increased by grazing or cutting during winter or spring. However, in order for these new stolons to contribute to clover yield during the summer, they have to be maintained until then by ensuring that competition from grass is minimized by keeping the sward short in winter and spring and avoiding the burial of stolons during grazing.
Growth and photosynthesis of tall and short cultivars of white clover with tall and short grasses
Authors: WOLEDGE JANE , DAVIDSON KERRY , DENNIS W. D. 
Published: April 2006

AbstractA comparison was made of canopy structure, photosynthesis and dry weight production, during growth periods in spring and summer, of a large‐leaved and a small‐leaved cultivar of white clover (Blanca and S184), grown in mixtures with perennial ryegrass or tall fescue. Both clovers had leaves in the topmost, best‐lit layer of the canopies, even when sward surface height reached 40 cm in early June. Except early in the spring growth period, both clovers had a greater proportion of their leaf area near the top of the canopy than did their companion grass. Both clovers had a greater relative growth rate than the grass, increasing their percentage of the total crop dry weight during both spring and summer growth periods. Differences between clover cultivars were relatively minor and did not affect their dry weight in either measurement period. During the first growth period there was more clover dry weight with tall fescue than with ryegrass. There were no effects of clover cultivar on grass dry weights.
Some effects of herbage composition, as influenced by previous grazing management, on milk production by cows grazing on ryegrass/white clover pastures. 2. Milk production in late spring/summer: effects of grazing intensity during the preceding spring period
Authors: HOOGENDOORN C. J. , HOLMES C. W. , CHU A. C. P. 
Published: April 2006

AbstractThree experiments (2a, 2b and 2c) were carried out to examine the effects of different grazing intensities imposed during spring on subsequent herbage composition and milk production measured in summer.Increased intensity of grazing imposed during spring (including the period of reproductive development in ryegrasses) produced swards in early summer with lower pre‐grazing herbage masses, which contained higher concentrations of green leaf, clover and digestible nutrients, but lower concentrations of grass stem and senescent material.In the first and second experiment cows were given a common daily allowance of total herbage dry matter (DM). The cows grazing on low‐mass swards in early summer produced larger daily yields of milk, fat and protein than those grazing on the high‐mass swards.In the third experiment, cows were given a common daily allowance of green leaf DM from three swards which differed in pre‐grazing herbage mass and in herbage composition. The allowances of total DM required differed widely between the treatments. There were no significant differences in milk yields between the swards despite the large differences in herbage composition.The practical implications of these results are discussed.
The effects of sward height and nitrogen fertilizer application on changes in sward composition, white clover growth and the stock carrying capacity of an upland perennial ryegrass/white clover sward grazed by sheep for four years
Authors: BARTHRAM G. T. , GRANT S. A. , ELSTON D. A. 
Published: April 2006

AbstractPerennial ryegrass/white clover pastures grazed by sheep and receiving either no fertilizer N (No) or 120 kg N ha−1 year−1 (N0) were maintained with surface heights of 2·5, 3·5 and 5·0 cm for over four years. The treatments were replicated.The white clover (WC) population was greatest in the N0treatment, and declined during the study. Between‐year variation in WC was negatively related to rainfall and positively related to temperature, WC as a proportion of the total plant population decreased during the summer in the Nl treatment. The perennial ryegrass (PRG) population was greater in the Nl treatment, declined during the study and both within and between years was positively related to temperature. The population density of the unsown grasses was highest in the N‐fertilized treatment and in the swards maintained at the lowest heights (these treatments also had the highest stocking rate); it increased during the study, within‐years being positively related to temperature and between‐years being positively related to rainfall.The WC stolon extension rate was largely unaffected by N fertilizer application and was greatest in the taller swards. Leaf appearance rate was unaffected by N fertilizer application and sward height; it was positively related to temperature and negatively related to rainfall.Branching rate was greater in the N0 treatment with significant sward height effects confined to a negative relationship with local sward height within treatment plots on one occasion; it was negatively related to rainfall. The ground level red:far red light ratio was negatively related to local sward height. The total live weight of sheep carried in the No treatments was 0·7 of that in the N1 treatments.Expected photomorphogenic responses by we were confined to stolon extension. It was concluded that on the poorly drained clay‐loam soil used in this study the effects of sheep, in interaction with climatic factors, had an overriding effect on clover branching rate and the ultimate species composition.
Preliminary trials using a white clover (Trifolium repens L.) understorey to supply the nitrogen requirements of a cereal crop
Authors: JONES L. 
Published: April 2006

AbstractA method of growing cereals with no input of N fertilizer was tested. Two experiments are reported in which white clover (Trifolium repens L.) was used to supply the nitrogen requirements of the cereal. Spring barley, spring oats and winter barley were direct drilled into an established clover crop and grown with the legume as an understorey. The yield of whole crop cereal, for ensilage, and yield of cereal grain were similar to those grown by traditional methods. In the first experiment, clover survived adequately to be used again, but in the second experiment it was killed by a very high slug population. A method of slug control by mob stocking with sheep is discussed. Where clover survived, no weed, insect or disease problems were encountered. The technique offers a possible method of reducing the environmental problems arising from the use of nitrogen fertilizers.