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1.
Swards based on a mixture of SI 70 tall fescue and S215 meadow fescue were very early in spring, gave high yields for conservation in mid-season and, rested from mid-August, gave good grazing in November-December. Under this treatment, the tall fescue assumed dominance, and the swards were persistent and remained productive. The digestibility of the tall fescue swards was always higher than that of swards based on cocksfoot with which they were compared. During spring and autumn the former sward was better grazed by stock, but the position was reversed in mid-summer. Cattle grazing tall-fescue-dominant swards made better liveweight gains than those grazing cocksfoot swards during November-December. 相似文献
2.
M. G. Agnusdei S. G. Assuero† R. C. Fernández Grecco J. J. Cordero† V. H. Burghi†‡ 《Grass and Forage Science》2007,62(1):55-65
Two experiments were carried out on a tall fescue sward in two periods of spring 1994 and on a tall wheatgrass sward in autumn 2001 and spring 2003 to analyse the effect of sward surface height on herbage mass, leaf area index and leaf tissue flows under continuous grazing. The experiment on tall fescue was conducted without the application of fertilizer and the experiment with tall wheatgrass received 20 kg P ha?1 and a total of 100 kg N ha?1 in two equal dressings applied in March (autumn) and end of July (mid‐winter). Growth and senescence rates per unit area increased with increasing sward surface height of swards of both species. Maximum estimated lamina growth rates were 28 and 23 kg DM ha?1 d?1 for the tall fescue in early and late spring, respectively, and 25 and 36 kg DM ha?1 d?1 for tall wheatgrass in autumn and spring respectively. In the tall fescue sward, predicted average proportions of the current growth that were lost to senescence in early and late spring were around 0·40 for the sward surface heights of 30–80 mm, and increased to around 0·60 for sward surface heights over 130 mm. In the tall wheatgrass sward the corresponding values during spring increased from around 0·40 to 0·70 for sward surface heights between 80 and 130 mm. During autumn, senescence losses exceeded growth at sward surface heights above 90 mm. These results show the low efficiency of extensively managed grazing systems when compared with the high‐input systems based on perennial ryegrass. 相似文献
3.
A. H. Charles 《Grass and Forage Science》1969,24(2):111-118
The annual yield of tall fescue was higher than that of Italian ryegrass in the third year after sowing, but the total yield of herbage from grass plus clover swards was similar.
In both the second and third year after sowing, the yield of herbage in the spring grazing was higher when fescue was used as the sown grass. The method of establishment of both tall fescue and Italian ryegrass affected the total and seasonal yield in the second and third year after sowing, but the magnitude of these effects was not nearly as marked as it was earlier in the life of the leys. In the second year after sowing, swards of both Italian ryegrass and tall fescue had a higher yield of total herbage and of white clover, and a lower ingress of unsown species, when established without a cover crop and grazed frequently in the year of sowing.
The inclusion of red clover did not increase total yield of DM in the second and third year after sowing, and it slightly decreased the yield of the tall fescue mixture in the third year following sowing when N was applied. S170 tall fescue was readily grazed by sheep in spring and autumn.
The apparent recovery of applied N varied with the mixture sown, and the management given during establishment. 相似文献
In both the second and third year after sowing, the yield of herbage in the spring grazing was higher when fescue was used as the sown grass. The method of establishment of both tall fescue and Italian ryegrass affected the total and seasonal yield in the second and third year after sowing, but the magnitude of these effects was not nearly as marked as it was earlier in the life of the leys. In the second year after sowing, swards of both Italian ryegrass and tall fescue had a higher yield of total herbage and of white clover, and a lower ingress of unsown species, when established without a cover crop and grazed frequently in the year of sowing.
The inclusion of red clover did not increase total yield of DM in the second and third year after sowing, and it slightly decreased the yield of the tall fescue mixture in the third year following sowing when N was applied. S170 tall fescue was readily grazed by sheep in spring and autumn.
The apparent recovery of applied N varied with the mixture sown, and the management given during establishment. 相似文献
4.
The milk-production potential of different sward types was measured in each of the four seasons of the year in a replicated experiment in south-west Victoria, Australia. Dairy cows were offered ad libitum allowances of a 'short-term winter' sward, based on Italian ryegrass (treatment STW), a 'long-term winter' sward, based on a winter-active tall fescue (treatment LTW), a 'long-term summer' sward, based on a summer-active tall fescue (treatment LTS) and a Control sward (perennial ryegrass) in four seasons (days in milk in parentheses): spring (November dairy cows, 124), summer (February, 227), autumn (May, 234) and winter (August, sixty-four). A 'short-term summer' sward, based on chicory and white clover (treatment STS), was also included in summer. There was a significant season × treatment interaction caused by a more gradual decline in milk yield from peak for cows grazing treatment LTS compared to the Control treatment in the transition period from spring to summer. In summer, cows grazing treatment STS produced more milk (1·41 kg fat plus protein per cow d−1 ) than cows grazing all other treatments (0·92 kg per cow d−1 ) because of the superior nutritive value of herbage of pre-grazing pasture and higher apparent dry-matter intakes. Swards based on alternative species to perennial ryegrass are capable of supporting milk production that is at least comparable over an annual cycle. 相似文献
5.
A. H. Charles 《Grass and Forage Science》1965,20(4):241-247
Tall fescue S170 and Italian ryegrass S22, slow- and rapid-establishing grasses, respectively, were sown either with white clover or with a mixture of red and white clovers, with or without a companion- or cover-crop, and with or without nitrogen. Swards established without a cover-crop were grazed frequently or cut infrequently; swards undersown with the oat crop were grazed once in the autumn. In the year of sowing tall fescue/clover mixtures produced yields similar to those of Italian ryegrass/clover swards. Tall fescue proved sensitive to competition, even from red clover, during establishment and sowing under a cover-crop is therefore not recommended. The yield of red- and white-clover was increased when sown under a cover-crop and when cut infrequently, compared with frequent grazing by sheep. The growth of white clover was greatly reduced by adding red clover to the mixture, particularly under a cover-crop and when defoliation was infrequent, but red clover increased total yield. The effect of N applied to the seed-bed varied with the method of establishment. Cereal yield was reduced under dry conditions by undersowing with a mixture containing red clover. 相似文献
6.
Yield profile characteristics of tall fescue (Festuca arundinacea Schreb.), cv. Retu, were compared with those of meadow fescue (Festuca pratensis Huds.). The study was conducted in Finland and was based on official variety trial data recorded between 1980 and 1998 at 17 trial sites between latitudes 60° and 66°N. The crops were managed according to silage‐cutting regimes. The pattern of yield formation of the tall fescue cv. Retu differed significantly from that of meadow fescue cultivars, both within a growing season as well as in sward age. Tall fescue cv. Retu established slowly, and the dry‐matter (DM) yield from the first cut, made in the first year of harvest, was significantly lower than that for meadow fescue. In the second and third years, the DM yield from the first cut did not differ between tall fescue and meadow fescue. Tall fescue produced significantly higher DM yield as regrowth (second and third cuts) than meadow fescue. The sward age significantly affected total DM production. In first‐year swards, there were no significant differences in total DM yield between tall fescue and meadow fescue but, in the second‐ and third‐year swards, tall fescue produced significantly higher DM yields than meadow fescue. The difference in yield profile between tall fescue and meadow fescue was similar in all the environments included in the study. DM yield for the first cut (kg DM ha–1) for tall fescue cv. Retu, in comparison with meadow fescue cultivars, was 2495 vs. 3099 (P < 0·001), 3735 vs. 3741 (NS, P=0·94) and 3553 vs. 3468 (NS, P=0·30) in the first‐, second‐ and third‐year swards respectively. The respective DM regrowth yields (second plus third cut) were: 6059 vs. 5416 (P < 0·001); 5445 vs. 4221 (P < 0·001); and 5580 vs. 4113 (P < 0·001) in first‐, second‐ and third‐year swards. Total DM yields per season for tall fescue vs. meadow fescue were (kg DM ha–1) 8554 vs. 8515 (NS, P=0·69), 9180 vs. 7962 (P < 0·001) and 9133 vs. 7581 (P < 0·001) in first‐, second‐ and third‐year swards respectively. Over the three‐year sward rotation period, which is common in Finland, tall fescue produced on average 12% higher DM yield than meadow fescue. Both tall fescue and meadow fescue suffered little winter damage in Finnish conditions; the differences between cultivars of the two species were small. The results indicated that tall fescue cv. Retu is a productive and persistent forage species suited to Finnish growing conditions. 相似文献
7.
M. C. Raeside M. A. Friend R. Behrendt A. R. Lawson S. G. Clark 《Grass and Forage Science》2012,67(3):411-425
Tall fescue (Festuca arundinacea Schreb.) is currently seldom used in the high‐rainfall (>600 mm) zone of south‐eastern Australia. To determine its potential to improve forage availability during the summer‐autumn feed‐deficit period, a field plot‐scale experiment with sheep evaluated a Continental cultivar of tall fescue (cv. Quantum) at Hamilton, Victoria, between September 2006 and January 2009. Four grazing treatments represented set stocking or rotational grazing at the two‐, three‐ or four‐leaf stage, in a completely randomized design with three replications. Grazing treatment effects on tall fescue tiller population dynamics, forage accumulation rates and consumption, sward nutritive value and botanical composition were measured. Results showed tall fescue can persist and support year‐round grazing by sheep, subject to water availability for summer growth from summer rain or on moisture retentive heavy soils. During the summer‐autumn (December–April) vegetative phase, grazing at the three‐leaf stage optimized forage consumption, with no difference in feed value or botanical composition between the grazing treatments during these months. During the reproductive phase (September–November), feed value was highest under set stocking and declined with the production of each successive leaf. Grazing at the three‐ or four‐leaf stage prevented winter weed invasion, but winter forage consumption was low in these treatments. Set stocking or grazing at the two‐leaf stage improved winter forage consumption rates, but these swards were invaded by winter growing weeds. 相似文献
8.
Four experiments are described in which various defoliation methods and frequencies were imposed on grass/white-clover swards. Clover was not reduced in any of these hy increasing the length of growth period or hy cutting at a late stage of growth, but intensive sheep grazing reduced clover compared nitb cutting and taking a silage cut in a grazing sequence improved clover yield. These results do not support the contention that cutting a mixed sward for hay or silage suppresses clover because of competition for light: with a ‘big white’ type of clover infrequent defoliation may cause no more shading than frequent. Alternatively, any additional shading may be compensated for by an increase in clover growth, stimulated hy the longer growth period. It is suggested that, in practice, competition for nutrients and moisture also contrihute towards clover suppression when swards are cut for hay or silage. 相似文献
9.
Cornelia Grace Tommy M. Boland Helen Sheridan Eugene Brennan Rochelle Fritch Mary Bridget Lynch 《Grass and Forage Science》2019,74(3):437-449
Dry matter (DM) production of multispecies swards compared to perennial ryegrass (Lolium perenne; PRG) swards under intensive grazing warrants investigation as it is relatively unknown. A 5 × 2 factorial experiment, with five sward types and two defoliation methods, was used to investigate the effect of grazing versus cutting on dry matter (DM) production of multispecies and PRG‐only swards. Five sward types were established namely: a PRG‐only sward, receiving 250 kg N ha?1 year?1 (PRG250), and a PRG‐only sward (PRG90), a two‐species sward with PRG and white clover (Trifolium repens; PRGWC), a six‐species sward (6S) and a nine‐species sward (9S), each receiving 90 kg N ha?1 year?1. Cutting plots measured 1.95 × 10 m and grazing plots measured 10 × 10 m. All plots were harvested concurrently every 21–30 days from April‐November for two years (2015 and 2016). A strip from the grazing plots was cut for DM yield determination prior to turning in cattle for grazing. There was an interaction between sward type and defoliation method (p < .01), whereby there was no effect of defoliation method on the PRG‐only swards, however, the annual DM production of PRGWC, 6S and 9S swards reduced under grazing compared to cutting (p < .001; on average 1,929 kg DM/ha lower). Multispecies swards had lower DM production under grazing compared to cutting, while the DM yield of PRG‐only swards was unaffected by defoliation method. 相似文献
10.
A. H. Charles 《Grass and Forage Science》1970,25(1):30-36
The effects of preeropping with Italian ryegrass and tall fescue mixtures on marrow-stem kale (1st test crop) and barley (2nd test crop) were measured. Application of N to the grass/clover swards reduced the yield of DM, P, K, Na, Mg, crude protein and also the percentage crude protein in the kale test-crop. Following the tall fescue swards, the yield of DM, P, Na, Ca, Mg and E, crude protein and percentage crude protein in the kale were lower than after the Italian ryegrass swards. These effects were particularly evident in the kale stem. Interactions occurred which involved the method used to establish the herbage mixtures, the application of N to the swards and of fertilizers to the kale. These effects were complex, but the method of sward establishment could clearly affect the following kale crop grown several years later. The influence of grass swards on the second test-crop (spring barley) was much smaller than on kale. Precropping with Italian ryegrass or using a cover crop during grassland establishment reduced 1000-grain weight of barley. The crude protein percentage in barley grain was reduced by the compound fertilizer applied to the previous kale crop, particularly when no cover crop had been used during establishment of the herbage mixtures. The converse of these effects was recorded in the crude-protein percentage of the straw of the barley test-crop. 相似文献
11.
Is the nutritive value of tall fescue (Festuca arundinacea Schreb.) related to the accumulated forage mass?
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The aim of this work was to investigate whether neutral detergent fibre (NDF) and dry‐matter digestibility (DMD) are related to tall fescue accumulated forage mass (AFM) and to assess the relevance of environmental variables to predict the nutritive value of tall fescue swards. Three experiments were carried out in Pergamino, Argentina. To obtain swards with different amounts of AFM, two N levels and two irrigation regimes were applied in the spring after sowing and the autumn of the next year. In spring and autumn, AFM, NDF and DMD were measured every 10–12 days. In spring, NDF increased from 503 to 604 g kg?1, DMD decreased from 684 to 558 g kg?1 and AFM increased from 0·64 to 2·82 t DM ha?1. In autumn, NDF decreased from 543 to 442 g kg?1, DMD increased from 591 to 681 g kg?1 and AFM increased from 0·35 to 1·10 t DM ha?1. The results show that the nutritive value of tall fescue through the year is not related to the accumulation of dry matter of the sward. Nutritive value is determined by the reproductive stage in late spring and early summer, the fate of photosynthates at different times of the year and the synthesis of non‐digestible compounds. 相似文献
12.
The effects of autumn management and nitrogenous manuring on the production of early spring grass were studied from 1954 to 1957 on farms throughout England and Wales.
The most important management factor influencing spring yields was the application of spring nitrogen. In the early spring 6 to 10 lb. of dry matter were produced per lb. of nitrogen applied. Autumn nitrogen increased herbage yields in the auttimn by 8 to 17 lb. of dry matter per lb. of nitrogen applied.
Italian and perennial ryegrass responded well to autumn nitrogen but it was important to graze off the extra growth fairly quickly to prevent the sward becoming too open. The yield of ryegrass swards which received spring nitrogen were very much higher if they were grazed during the previous September and October than if they had been rested during those months.
In two years neither the autumn management nor alumni fertilizer appeared to influence the spring yields of cocksfoot, timothy or meadow fescue swards, in one year, however, when autumn growth was poor, autumn nitrogen and resting resulted in slightly better yields on these swards in the following spring.
It is suggested that resting swards during September and October to build up "reserves" is relatively unimportant in relation to the yields of grass in the following spring. 相似文献
The most important management factor influencing spring yields was the application of spring nitrogen. In the early spring 6 to 10 lb. of dry matter were produced per lb. of nitrogen applied. Autumn nitrogen increased herbage yields in the auttimn by 8 to 17 lb. of dry matter per lb. of nitrogen applied.
Italian and perennial ryegrass responded well to autumn nitrogen but it was important to graze off the extra growth fairly quickly to prevent the sward becoming too open. The yield of ryegrass swards which received spring nitrogen were very much higher if they were grazed during the previous September and October than if they had been rested during those months.
In two years neither the autumn management nor alumni fertilizer appeared to influence the spring yields of cocksfoot, timothy or meadow fescue swards, in one year, however, when autumn growth was poor, autumn nitrogen and resting resulted in slightly better yields on these swards in the following spring.
It is suggested that resting swards during September and October to build up "reserves" is relatively unimportant in relation to the yields of grass in the following spring. 相似文献
13.
Factors affecting grazing preference by sheep in a breeding population of tall fescue (Festuca arundinacea Schreb.)
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M. Cougnon R. Shahidi J. Schoelynck I. Van Der Beeten C. Van Waes P. De Frenne M.‐C. Van Labeke D. Reheul 《Grass and Forage Science》2018,73(2):330-339
A disadvantage of tall fescue (Festuca arundinacea Schreb.) is its low voluntary intake, resulting in suboptimal performance under grazing. Ideally, selection for this trait is done using grazing animals, but their use in plant breeding programmes is costly and laborious. Repeatable, stable and quantifiable traits linked to animal preference could ease tall fescue breeding. We established a trial to find relationships between the grazing preference of sheep and sward‐ and plant‐related traits. Seventeen genotypes were studied in swards. Sheep grazing preference, pre‐grazing sward height (SH), leaf softness, leaf blade length, width, colour and shear strength, and concentration of fibre, silica, digestible organic matter (DOM) and water‐soluble carbohydrate (WSC) were quantified throughout the growing season. The traits with the strongest correlation with sheep preference were DOM, SH, leaf colour, leaf width and WSC. Leaf softness, silica content and leaf shear strength were not correlated with sheep preference. We conclude that DOM is the trait that offers the best prospects for contributing to progress in tall fescue plant breeding for both intake and feeding value. 相似文献
14.
Two cutting treatments were applied to a cocksfoot sward, and the changes in fructosan and soluble–sugar contents of the roots, stubble and herbage were studied over a complete year.
Both the soluble-sugar and fructosan contents of roots were at a low level throughout the experiment. The total soluble carbohydrate in the roots never exceeded 4%. It is concluded that cocksfoot roots are not important storage regions for soluble carbohydrates.
The total soluble carbohydrate in herbage varied with season and reached a maximum of 10%. It was not affected by cuuing treatment.
In stubble the total stubble-carbohydrate content fluctuated markedly with season and reached a maximum of 18% in October; it was generally higher on the infrequently-cut swards than on those cut frequently. The soluble-sugar content was small and changed little with season or cutting treatment; the fructosan content, however, varied from 2 to 16–6% and accounted for most of the changes in the soluble-carbohydrate content. Stubble is apparently the major storage region for soluble carbohydrates in cocksfoot.
Under sward conditions, the quantity of soluble carbohydrates in the stubble of cocksfoot may have a positive effect on the herhage growth immediately after winter defoliation. However, when swards are actively growing in spring, other factors, such as tiller size and number, may be equally important in determining the amount of herbage recovery growth. 相似文献
Both the soluble-sugar and fructosan contents of roots were at a low level throughout the experiment. The total soluble carbohydrate in the roots never exceeded 4%. It is concluded that cocksfoot roots are not important storage regions for soluble carbohydrates.
The total soluble carbohydrate in herbage varied with season and reached a maximum of 10%. It was not affected by cuuing treatment.
In stubble the total stubble-carbohydrate content fluctuated markedly with season and reached a maximum of 18% in October; it was generally higher on the infrequently-cut swards than on those cut frequently. The soluble-sugar content was small and changed little with season or cutting treatment; the fructosan content, however, varied from 2 to 16–6% and accounted for most of the changes in the soluble-carbohydrate content. Stubble is apparently the major storage region for soluble carbohydrates in cocksfoot.
Under sward conditions, the quantity of soluble carbohydrates in the stubble of cocksfoot may have a positive effect on the herhage growth immediately after winter defoliation. However, when swards are actively growing in spring, other factors, such as tiller size and number, may be equally important in determining the amount of herbage recovery growth. 相似文献
15.
H. M. Roberts 《Grass and Forage Science》1965,20(4):283-289
Leafy grass varieties S24 perennial ryegrass, S26 cocksfoot, S215 meadow fescue and S51 timothy were cut in October and at various growth stages in spring; S53 meadow fescue was grazed at similar periods. Sub-plots were given different applications of N. The control plots had similar manurial treatments but were not defoliated. The seed yield of S24 following October cutting was significantly lower than the control in the first harvest year and significantly higher in the second; the mean yields over 2 years, as a result of cutting at this stage and before ear formation in March, were very similar to those of the control treatment. The mean yields from 3 harvest years for S26, S215 and S51 were generally improved by cutting in October and before ear formation, but cutting after ear formation reduced the number of heads and the seed yields. Extra N applied in conjunction with the defoliation had no significant effect on the number of seed heads or on seed yield. Double grazing of S53 in Sept. and Dec. reduced significantly its seed production in both harvest years. Application of N in spring gave a greater response than a similar application in autumn. 相似文献
16.
Implications of nitrogen fertilizer applications and extended grazing for the N economy of grassland
The response of swards which have been previously grazed to N fertilizer applied in early February was studied in two experiments in Northern Ireland. The effect of N fertilizer applied at a range of dates in autumn and spring on swards for out-of-season utilization was studied in a further experiment. Deep soil coring was also undertaken, subsequent to grazing with dairy cows, in grazed and protected areas in November and March to investigate the effect of out-of-season grazing on soil mineral N levels.
Dry-matter (DM) yield response to early spring N application in previously grazed swards was low, with no effect on DM yield in February or March. Progressively delaying N application (and commencement of herbage accumulation) in autumn from 8 September until 18 October reduced herbage availability in late autumn and early spring but increased leaf lamina content. The greater the amount of herbage accumulated to 1 December, the lower the tiller density in the following April.
N fertilizer had a greater impact on soil mineral N in spring than in late autumn/early winter, suggesting that fertilizer N was more prone to loss in the latter. Soil mineral N was not significantly affected by out-of-season grazing.
It is concluded that in well-fertilized, previously grazed swards response to N for out-of-season herbage is low and the probability for N loss is increased. Herbage quality will decline and the sward may be damaged if about 2 t DM ha−1 or more of harvestable herbage accumulates for use in winter or in early spring. 相似文献
Dry-matter (DM) yield response to early spring N application in previously grazed swards was low, with no effect on DM yield in February or March. Progressively delaying N application (and commencement of herbage accumulation) in autumn from 8 September until 18 October reduced herbage availability in late autumn and early spring but increased leaf lamina content. The greater the amount of herbage accumulated to 1 December, the lower the tiller density in the following April.
N fertilizer had a greater impact on soil mineral N in spring than in late autumn/early winter, suggesting that fertilizer N was more prone to loss in the latter. Soil mineral N was not significantly affected by out-of-season grazing.
It is concluded that in well-fertilized, previously grazed swards response to N for out-of-season herbage is low and the probability for N loss is increased. Herbage quality will decline and the sward may be damaged if about 2 t DM ha
17.
Tall fescue is an important temperate grassland species globally, but in many regions the effects of drought, heat and poor grazing management, reduce its persistence in summer. Furthermore, poor ground cover and low tiller population density (TP) in winter result in low radiation capture and thus limited potential to increase the low growth rates at that time. Knowledge of the effect of fertilization, defoliation managements and establishment methods on demography of tall fescue would help to improve sward management for better persistence and winter growth. Accordingly, an experiment was carried out in Pergamino, Argentina, to study the effects of two N‐ fertilizer levels, two grazing frequencies and two seeding row arrangements upon tall fescue TP demography. Herbage mass, tiller appearance (TA) and death rates were measured over 3 years. Seasonal fluctuations in TA and death rates determined well‐defined periods of increase and decrease in TP density. Maximum values were found at the end of winter and minimum ones at the end of spring, after the reproductive period. Nitrogen shortage and high herbage mass limited TA. Tiller death rate followed TA rate and was affected by nitrogen supply and defoliation frequency in the same way that TA was. Sowing arrangement affected tiller demography at the beginning of the experiment. 相似文献
18.
S. J. Cowlishaw 《Grass and Forage Science》1960,15(1):6-11
An experiment was carried out in two parts to investigate lack of persistency of white clover in a meadow fescue/white clover sward when grazed by poultry. It was found that poultry manure was responsible for a considerable part of this depressing effect. Grazing by poultry in the autumn and winter was nearly as effective in reducing the clover conlent of the sward as grazing for the whole year, autumn grazing being particularly harmful. Autumn and winter grazing alone increased the number of sown grass tillers and reduced Poa tririalis tillers in comparison wilh all-the-year-round grazing. Range and fold grazing at a high stocking rate (312 per acre in the first winter) both had the same effect on the sward. The effects of drought and continual close mowing on white clover persistence are discussed. Fertilizers containing calcium, potassium and phosphorus might counteract the depressing effect of poultry grazing and manure on white clover. 相似文献
19.
A study was made to determine the effects of grazing to a height of 1 in. when the swards reached heights of 3 and 9 in. on the dry matter production, LAI, tillering and rate of leaf production of new and old tillers in the spring–summer and autumn–winter seasons of 3 pasture species growing in association with white and red clovers. In both seasons the herbage yield under 9–1 management was higher than that under 3–1 and was significantly greater in the spring-summer season. Differences in DM production between cocksfoot, tall fescue and Ariki ryegrass failed to reach significance.
Light utilization under the 2 management systems was considered to be inefficient. In the autumn-winter period there was a linear relationship between the LAI and DM production in all treatments.
The rate of leaf production per tiller was significantly higher in cocksfoot than in ryegrass and tall fescue in both seasons.
New tillers had a significantly higher rate of leaf production than old tillers in the spring-summer period, but not in autumn-winter. The numbers of grass tillers and rooted nodes of clover were significantly higher under 3–1 than under 9–1 and were influenced by season. 相似文献
Light utilization under the 2 management systems was considered to be inefficient. In the autumn-winter period there was a linear relationship between the LAI and DM production in all treatments.
The rate of leaf production per tiller was significantly higher in cocksfoot than in ryegrass and tall fescue in both seasons.
New tillers had a significantly higher rate of leaf production than old tillers in the spring-summer period, but not in autumn-winter. The numbers of grass tillers and rooted nodes of clover were significantly higher under 3–1 than under 9–1 and were influenced by season. 相似文献
20.
Three experiments were carried out on perennial ryegrass‐dominant swards to provide a basis for recommendations for the limits to (a) building up and timing of utilization of a herbage ‘bank’ for out‐of‐season grazing and (b) duration and intensity of early spring grazing in the United Kingdom and Ireland. In experiment 1, the effect of regrowth interval (from 7 September, 20 October, 17 November or 15 December) in autumn on herbage accumulation, leaf turnover and on subsequent spring growth was investigated. Swards regrown from early September reached maximum herbage mass (about 3 t ha–1 DM) and leaf lamina content in mid‐November, by which time senescence rate exceeded rate of production of new leaves. New leaf production and senescence rates were greater in swards remaining uncut until December than in those cut in October or November. Time of defoliation up to December had no effect on spring herbage mass in the subsequent spring. Defoliating in March reduced herbage mass in late May by less than 20%. Experiment 2 investigated the progress in herbage growth and senescence in swards regrowing from different times in late summer and autumn to produce herbage for utilization beyond the normal grazing season. Treatments in a randomized block design with three replicates were regrowths from 19 July, 8 August, 30 August and 20 September. Based on a lower ceiling of leaf and total herbage mass being reached with progressively later regrowths, beyond which leaf senescence generally exceeded leaf production and herbage mass declined, it was concluded that currently recommended rotation lengths for this period should extend from 3 weeks in late July to 8 weeks for swards previously grazed in mid‐September. In both experiments, leaf senescence commenced earlier (by one leaf‐age category) than previously published estimates and so brought forward the time at which senescence rates balanced leaf growth rates. In experiment 3, designed to evaluate the effect of daily grazing period and intensity in early spring on herbage regrowth, dairy cows grazed successive plots (replicates) for 2 or 4 h each day at two intensities (target residual heights of 5 or 7 cm) in March to mid‐April. Regrowth rate was similar in all treatments including the ungrazed control, despite soil moisture content being relatively high on occasions. Tiller density was significantly reduced in May by grazing plots in early or mid‐April. It is concluded that in autumn there are limits to which rotation lengths should be extended to produce herbage for out‐of‐season grazing owing to attainment of ceiling yields. Although utilization in early spring may reduce herbage availability in spring, out‐of‐season utilization need not reduce herbage growth rates in early spring. 相似文献