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1.
Two red clover ( Trifolium pratense ) cultivars, Red Head (tetraploid) and Kuhn (diploid), were sown at a seed rate of 13 kg ha−1 either alone or in mixture with Italian ryegrass ( Lolium multiflorum ) cv. RvP sown at seed rates of 10, 15, 20 or 30 kg ha−1 . RvP was also sown alone at a seed rate of 30 kg ha−1 and received nil or 300 kg ha−1 fertilizer a−1 fertilizer N. All plots were established using the barley cultivar Midas sown at a seed rate of 100 kg ha−1 as a nurse crop.
Neither clover cultivar nor ryegrass seed rate significantly influenced either dry matter harvested or botanical composition over the 3 harvest years. On average over all years the grass-clover mixtures produced 75% of the yield of the N-fertilized RvP, 125% of the clover monocultures and 225% of the unfertilized RvP. The red clover contribution to the total dry matter harvested of the mixtures averaged 45–60%. The dry matter concentrations of the mixtures were considerably higher than those of the pure clover stands. In the third year yields were markedly reduced in comparison with those in the first and second years.
It was concluded that Italian ryegrass can be a suitable companion grass for red clover. Its superior yielding capacity over other grasses such as perennial ryegrass or timothy under a conservation management can be coupled to advantage with red clover to give a sward which Is essentially stable, at least over a 2- to 3-year cropping period, although giving slightly reduced yields in the third year. Italian ryegrass-red clover mixtures, without the use of fertilizer N, can produce high DM yields of good quality herbage. 相似文献
Neither clover cultivar nor ryegrass seed rate significantly influenced either dry matter harvested or botanical composition over the 3 harvest years. On average over all years the grass-clover mixtures produced 75% of the yield of the N-fertilized RvP, 125% of the clover monocultures and 225% of the unfertilized RvP. The red clover contribution to the total dry matter harvested of the mixtures averaged 45–60%. The dry matter concentrations of the mixtures were considerably higher than those of the pure clover stands. In the third year yields were markedly reduced in comparison with those in the first and second years.
It was concluded that Italian ryegrass can be a suitable companion grass for red clover. Its superior yielding capacity over other grasses such as perennial ryegrass or timothy under a conservation management can be coupled to advantage with red clover to give a sward which Is essentially stable, at least over a 2- to 3-year cropping period, although giving slightly reduced yields in the third year. Italian ryegrass-red clover mixtures, without the use of fertilizer N, can produce high DM yields of good quality herbage. 相似文献
2.
J. FRAME 《Grass and Forage Science》1990,45(1):57-64
Red fescue ( Festuca rubra L.) cvs Reptans, Dawson and Ruby, perennial ryegrass ( Lolium perenne L.) cvs Perma and Sprinter, crested dogstail ( Cynosurus cristatus L.) cv. Southlands, smooth meadow-grass ( Poa pratensis L.) cvs Parade and Arena, Yorkshire fog ( Holcus lanatus L.) commercial types I and II, creeping bent ( Agrostis stolonifera L.) cv. Penncross and rough meadow-grass ( Poa trivialis L.) cvs Omega Øtofte, Dasas and Sabre were each sown with white clover ( Trifolium repens L.) cv. Donna and the productivity of the fourteen mixtures assessed under simulated grazing (six harvests per year) for 3 years. A single fertilizer-N rate (50 kg ha−1 ) in early spring was applied to all treatments each year.
Over the 3 years, mean annual dry matter (DM) production of the swards ranged from 5·25 t ha−1 (creeping bent) to 8·71 t ha−1 (red fescue cv. Reptans), with the species ranking order of: red fescue > perennial ryegrass > crested dogstail > smooth meadow-grass > Yorkshire fog > creeping bent. Rough meadow-grass only persisted over the first harvest year. Mean annual organic matter digestibility (OMD) values of the swards ranged from 0·712 (creeping bent) to 0·782 (ryegrass cv. Sprinter). Mixtures with the lowest proportion of grass (crested dogstail and smooth meadow-grass) generally gave the highest proportions of white clover. The creeping bent mixture had exceptionally low production of both components.
Red fescue, crested dogstail and smooth meadow-grass showed compatibility with clover and, therefore, have potential for use in grass/clover swards. Yorkshire fog had lower compatability with clover. Some breeding effort to improve selected characteristics of promising species, e.g. improvement of low OMD in red fescue, seems warranted. 相似文献
Over the 3 years, mean annual dry matter (DM) production of the swards ranged from 5·25 t ha
Red fescue, crested dogstail and smooth meadow-grass showed compatibility with clover and, therefore, have potential for use in grass/clover swards. Yorkshire fog had lower compatability with clover. Some breeding effort to improve selected characteristics of promising species, e.g. improvement of low OMD in red fescue, seems warranted. 相似文献
3.
Established swards of two diploid and two tetraploid red clover varieties sown pure received 0, 75, 150, 225 or 300 kg ha?1 N fertilizer and were cut three times in June, August and October 1971. The total yields of herbage DM for red clover varieties ranged from 8.01 to 11.32 t ha?1; swards sown with tetraploids Hungaropoly and Hera Pajbjerg were superior by 25% in DM yield and 23% in CP yield. The red clover contribution to these total yields of DM ranged from 6.05 to 10.69 t ha?1; tetraploid clovers outyielded diploids by 42% in DM yield and 39% in CP yield. The mean effect of N level on yield and on compositional attributes was slight. Total yields of herbage DM, averaged over all varieties, ranged from 9.50 to 10.22 t ha?1 and of total herbage CP from 1.76 to 1.91 t ha?1. The influence of N level on the red clover contribution was negligible. DM yields ranged from 8.54 to 8.72 t ha?1 and CP yields from 1.60 to 1.64 t ha?1. Superiority of tetraploid clovers over diploids was again confirmed. Red clover swards sown pure can give high yields without the application of fertilizer N. 相似文献
4.
The effect of growth regulators on the yield and quality of red clover ( Trifolium pratense L.) was assessed in two growing seasons. An early-flowering cultivar (Florex) and a late-flowering one (Altaswede) were treated with the growth regulator, daminozide butanedioic acid [mono (2,2-dimethylhydnizide)] or mefluidide [ N -(2,4-dimethyl-5{[(trifluoromethyl)sulphonyl]amino}phenyl) acetamide], either in early (mid-May) or late (late May) season and at low rate [daminozide, 4kg active ingredient (a.i.) ha−1 ; or mefluidide, 0·13 kg a.i. ha−1 ] or twice the low rate (high rate), and compared with no treatment. Red clover yielded two- to three-fold more dry mater (DM) in the first than in the second harvest, and growth regulator treatments did not redistribute yields more evenly between the two harvests. Growth regulator effects on the yield and composition of red clover were mainly confined to the first cut herbage. Daminozide increased first-cut and annual yields of DM and in vitro digestible DM (TVD); the latter was increased particularly for Altaswede, as compared with the untreated red clover. Mefluidide decreased first-cut yields of DM and IVD for Florex only, but the annual yields for both cultivars were unchanged by this treatment. Changing the rate or time of growth regulator application did not affect DM or IVD yield in red clover. The treated red clover contained less water-soluble carbohydrate in the first cut than did the untreated crop. The high rate of daminozide, when applied early, decreased neutral detergent fibre and increased IVD contents in the first-cut red clover compared with the other combinations of rate and time. Altaswede produced as much DM annually and had a higher IVD content than Florex when these cultivars were cut on common dates, twice during the short growing season in Atlantic Canada. 相似文献
5.
Replicated plots of Hungaropoly red clover were sown on a sterilized area in May 1975 alone (seed rate 11 kg ha-1 ) or with one of six cultivars of perennial ryegrass (seed rate 3·5 kg ha-1 ) viz. Cropper and S24 (early heading), Barlenna and Hora (medium heading) and Melle and Perma (late heading). In 1976 and 1977 primary growth was cut at one of four dates ranging from mid-May to mid-June and thereafter plots were harvested twice each year.
Varying the time of first cut did not have a significant effect on total dry matter (DM) yield in either year despite differences in means of cutting treatments on annual red clover yields of the order of 6–9%.
In some companion grass treatments total DM yield in 1976 was increased and total red clover yield and percentage red clover contribution were reduced relative to swards sown only with red clover. In 1977 a similar but non-significant trend was found. Swards containing early ryegrasses had higher total herbage DM yields but lower red clover yields and contents than all other swards at the first harvest in both years.
Delay in date of taking the first harvest in 1976 reduced DM digestibility in the first cut and increased it in the second in both years.
It is suggested that by cutting early and increasing the number of harvests from three to four per year, differences in the content of red clover between the first and second cut might be reduced, and it is concluded that more benefit is derived from red clover when medium or late heading ryegrasses are used as companion grasses. 相似文献
Varying the time of first cut did not have a significant effect on total dry matter (DM) yield in either year despite differences in means of cutting treatments on annual red clover yields of the order of 6–9%.
In some companion grass treatments total DM yield in 1976 was increased and total red clover yield and percentage red clover contribution were reduced relative to swards sown only with red clover. In 1977 a similar but non-significant trend was found. Swards containing early ryegrasses had higher total herbage DM yields but lower red clover yields and contents than all other swards at the first harvest in both years.
Delay in date of taking the first harvest in 1976 reduced DM digestibility in the first cut and increased it in the second in both years.
It is suggested that by cutting early and increasing the number of harvests from three to four per year, differences in the content of red clover between the first and second cut might be reduced, and it is concluded that more benefit is derived from red clover when medium or late heading ryegrasses are used as companion grasses. 相似文献
6.
Comparison of white clover varieties under cutting and grazing 总被引：2，自引：0，他引：2
G. SWIFT† M. W. MORRISON† A. T. CLELAND† C. A. B. SMITH-TAYLOR† J. M. DICKSON‡ 《Grass and Forage Science》1992,47(1):8-13
Seven varieties of white clover ( Trifolium repens L.), of varying leaf size from large to small, were sown with perennial ryegrass ( Lolium perenne L.) in 1985, at an upland site, and compared over three harvest years under a cutting management (5-6 cuts), and under continuous grazing by sheep. Fertilizer N input totalled 80 kg ha−1 in both the cutting and the grazing trial. The same varieties were included in two official National List (NL) trials sown the same year at a nearby site; these comprised a yield trial with 6-7 cuts and a persistency trial mown very frequently (17 cuts) to simulate intensive grazing.
At the upland site the large-leaved varieties, Milkanova and Blanca, were the highest yielding under cutting (mean 3·3 t DM ha−1 ), and the small-leaved S184 and Kent the lowest yielding (mean 2·3 t DM ha−1 ). The rankings were reversed under grazing (corresponding yields 1·1 and 2·1 t DM ha−1 ). The medium-leaved varieties Donna, Menna and Grasslands Huia behaved similarly to the large-leaved varieties. Ranking order in the cutting trial was similar to that in the NL trial.
Ground covers after three harvest years differed significantly only under grazing, when the small-leaved varieties had a 2-3 times greater cover than the larger-leaved varieties. A poor separation of the varieties in the NL persistency trial suggests that defoliation was not sufficiently severe to simulate intensive grazing.
These comparisons indicate that the performance of clover varieties under the cutting regimes used should not be extrapolated to continuous sheep grazing. 相似文献
At the upland site the large-leaved varieties, Milkanova and Blanca, were the highest yielding under cutting (mean 3·3 t DM ha
Ground covers after three harvest years differed significantly only under grazing, when the small-leaved varieties had a 2-3 times greater cover than the larger-leaved varieties. A poor separation of the varieties in the NL persistency trial suggests that defoliation was not sufficiently severe to simulate intensive grazing.
These comparisons indicate that the performance of clover varieties under the cutting regimes used should not be extrapolated to continuous sheep grazing. 相似文献
7.
The productivity of permanent swards of mixed species composition was compared with that of sown Lolium perenne , cv. Melle at five fertilizer-N rates (0, 150, 300, 450 and 900 kg N ha−1 ) and with L. perenne/Trifolium repens , cv. Grasslands Huia at 0 kg N ha−1 . The investigation was conducted under two cutting frequencies at sixteen sites in England and Wales, representing a range of grassland environments.
Annual total herbage dry matter (DM) production from both permanent and reseeded swards increased with successive increments of fertilizer-N up to 450 kg N ha−1 . Herbage DM production from reseeded swards in the first year after sowing was signficantly higher than from the permanent swards, at all fertilizer-N treatments. In subsequent years the production advantage of the L. perenne reseeds was maintained only at the higher N rates, though sown L. perenne/T. repens was the most productive sward type at 0 N. Average differences in modified acid-detergent fibre suggested small advantages in herbage quality to the reseeded swards.
It is concluded that, while reseeded swards are more productive in the year after sowing, many permanent swards are capable of high levels of production and that reseeding to a L. perenne sward cannot always be justified, particularly for grassland receiving low or moderate inputs of fertilizer-N. 相似文献
Annual total herbage dry matter (DM) production from both permanent and reseeded swards increased with successive increments of fertilizer-N up to 450 kg N ha
It is concluded that, while reseeded swards are more productive in the year after sowing, many permanent swards are capable of high levels of production and that reseeding to a L. perenne sward cannot always be justified, particularly for grassland receiving low or moderate inputs of fertilizer-N. 相似文献
8.
The forage potential of several annual winter legumes – crimson clover ( Trifolium incarnatum L.), faba beans ( Vicia faba L.), forage peas ( Pisum sativum L.), serradella ( Ornithopus sativus Brot.) and vetches ( Vicia sativa L. and Vicia villosa Roth.) – was evaluated over two growing seasons in the wet and mild winter areas of Galicia (north-west Spain) with a moderately acid soil, at the two normal harvesting dates in the region, April and May.
The results indicate that, in April, serradella and crimson clover (in the warmer location), can produce dry-matter (DM) yields of 4–5 t ha−1 , which is similar to other winter forages in the same area, with an average growing season of 212–237 d, corresponding to about 339–420 accumulated degree–days above 10°C (GDD10 ). In May, mainly in the warmer location, fava beans, peas and vetches yielded on average 4·7–8·5 t ha−1 DM, with an average growing season of 166–206 d but with only 233–278 GDD10 units. Faba bean, with an average of 8·5 t ha−1 DM in the May harvest, was the highest producing forage legume. The results also suggest that some cool-season legumes could fit into double-cropping systems based on summer crops, such as maize, because of their forage yields and nutritive value. However, in order to produce consistent DM yields, the date of sowing is crucial; they must either be sown much earlier than the dates in this study or the harvests must be delayed until the end of April. 相似文献
The results indicate that, in April, serradella and crimson clover (in the warmer location), can produce dry-matter (DM) yields of 4–5 t ha
9.
Three small plot experiments were conducted to investigate the effects of species of grass and forbs, defoliation regime, inclusion of white clover and forb blend on the herbage dry matter (DM) yield, botanical composition and mineral content of swards managed with zero fertilizer inputs. The results of all three experiments were characterized by decline in herbage production and large variations in treatment effects over the harvest period.
When sown singly with a standard grass mix the species that competed well with grasses and produced annual forb herbage yields greater than 20 t DM ha−1 were black knapweed, oxeye daisy, ribwort plantain, burnet, birdsfoot trefoil, chicory, kidney vetch, red clover and white clover. When sown singly with a standard forb mix, grass species significantly affected the annual yield of total ( P <005). grass ( P <001) and forb ( P <0.001) herbage. The species that most surpressed the yield of forbs were common bent, Yorkshire fog and perennial ryegrass. Those that allowed for the highest yield of forbs were rough meadow grass, sweet vernal grass and crested dogstail. Averaged over the three harvest years, defoliation regime did not significantly affect herbage production, but the inclusion of white clover in mixtures increased the yield of grasses ( P <0.01) The use of rosette-type forb blends increased forb yield ( P <0.01), compared with erect-type blends.
The effects of treatments on herbage N and mineral contents and yields were inconsistent. However, there was some evidence to support the view that the presence of forb species in swards can result in greater contents of minerals in herbage, compared with grass-only swards. 相似文献
When sown singly with a standard grass mix the species that competed well with grasses and produced annual forb herbage yields greater than 20 t DM ha
The effects of treatments on herbage N and mineral contents and yields were inconsistent. However, there was some evidence to support the view that the presence of forb species in swards can result in greater contents of minerals in herbage, compared with grass-only swards. 相似文献
10.
A. H. Marshall T. A. Williams H. G. Powell M. T. Abberton T. P. T. Michaelson-Yeates 《Grass and Forage Science》2002,57(3):232-238
Abstract Introgression of reproductive traits from ball clover (Trifolium nigrescens Viv.) into white clover (Trifolium repens L.) is one breeding strategy to improve seed yields of T. repens that must be achieved without sacrificing agronomic performance and persistency. The yield and persistency of hybrids between white clover and the annual, profuse flowering species T. nigrescens were compared under a cutting regime over three harvest years. The hybrids included the F1 and the backcross (BC) 1, 2 and 3 generations produced using T. repens as the recurrent parent. Parental species and hybrids were sown with a perennial ryegrass companion; clover and perennial ryegrass dry‐matter (DM) yield and the proportion of clover present were measured over the growing season. In the third harvest year, a portion of each plot was grazed. Differences were observed between T. nigrescens, the F1 and the backcross hybrids and T. repens. In the first and second harvest years, clover DM yield, the proportion of clover present and total DM yield of the backcross hybrids were similar to T. repens, whereas that of the T. nigrescens and the F1 hybrid were negligible. No significant difference in perennial ryegrass production was observed between the parental species and the hybrids when grown, respectively, in combination with these species and hybrids. In the third harvest year, clover DM yield and the proportion of clover present with the BC3 was lower than with T. repens. Throughout the growing season the DM production of T. repens and the backcross hybrids was similar. In the third harvest year, under cutting, DM yield of T. repens was greatest and that of the BC3 lowest, but under grazing, the yields of the BC1 and BC3 were greater than T. repens and the BC2. The implication of these results for the future development of these hybrids is discussed. 相似文献
11.
The use of sward height as a criterion for determining the time and extent of stocking-rate changes on continuously grazed swards was investigated over a 2-year period (1985–86) in a sheep production experiment. Swards of three contrasting perennial ryegrass ( Lolium perenne L.) varieties were established with and without Aberystwyth S184 small-leaved white clover ( Trifolium repens L.) at an upland site (310–363 m) in mid-Wales. From spring (late April) until weaning (mid-July) the pastures were continuously stocked with Beulah Speckled Face ewes and Suffolk cross lambs. During this period sward heights of 4 ± 0.5 cm were obtained and maintained by regular adjustment of animal number on individual paddocks. Grass-only swards received 160 and 200 kg N ha−1 and the grass clover swards were given 80 and 75 kg N ha−1 in 1985 and 1986 respectively.
Differences were observed between the treatments in sward height profiles over the season necessitating contrasting adjustments to stocking rates. Mean stocking rate necessary on early flowering Aurora (22 6 ewes ha−1 ) was respectively 27% and 17% higher than on late-flowering Aberystwyth S23 and Meltra (tetraploid) ryegrasses; mean stocking rate on grass-only swards was 19% higher than on the grass-clover pastures.
It is concluded that sward height is a useful criterion on which to make adjustments to stocking rates to compare the potential performance of contrasting swards, under continuous grazing. The infrequent adjustments required to maintain a constant sward height, especially on the late flowering diploid perennial ryegrass variety on which many upland pastures are based, suggest that the criterion of sward height could be successfully employed on farms as an aid to efficient grazing management. 相似文献
Differences were observed between the treatments in sward height profiles over the season necessitating contrasting adjustments to stocking rates. Mean stocking rate necessary on early flowering Aurora (22 6 ewes ha
It is concluded that sward height is a useful criterion on which to make adjustments to stocking rates to compare the potential performance of contrasting swards, under continuous grazing. The infrequent adjustments required to maintain a constant sward height, especially on the late flowering diploid perennial ryegrass variety on which many upland pastures are based, suggest that the criterion of sward height could be successfully employed on farms as an aid to efficient grazing management. 相似文献
12.
J. M. McBRATNEY 《Grass and Forage Science》1984,39(2):167-175
Three diploid—Sabtoron, Violetta and Essex—and three tetraploid—Hungaropoly, Teroba and Red Head—red clover cultivars were sown alone and with each of three companion grasses—timothy (S48), tall fescue (S170) and perennial ryegrass (S24). The productivity and persistence of the red clover cultivars were compared. Results obtained over the first four harvest years were presented in an earlier paper (McBratney, 1981) and this paper presents results from the fifth and sixth (final) harvest years.
The low yield obtained in the fifth and sixth year from Essex under each seeding treatment indicated a deterioration in its persistency or vigour or both. In the fifth year the remaining two diploids, Sabtoron and Violetta, were as highly productive and persistent as the three tetraploids but in the sixth year the decrease in productivity was greater in the diploids than in the tetraploids. In the fifth year Teroba, the highest yielder, produced 9 8 t total DM ha−1 over all seeding treatments of which 73% was clover DM; in the sixth year Teroba was again highest yielding, producing 9.3 t ha−l with 67% clover content. Tall fescue was the most consistent companion grass in the mixed swards, in the sixth year contributing 53% grass DM to the total 8 8 t DM harvested ha−1 .
The trial demonstrates the potential of a number of red clover cultivars grown either pure or with a suitable perennial grass to achieve and maintain a high output of herbage of good quality over a period of 6 years without any application of fertilizer N. The practical agricultural implications of using red clover are discussed. 相似文献
The low yield obtained in the fifth and sixth year from Essex under each seeding treatment indicated a deterioration in its persistency or vigour or both. In the fifth year the remaining two diploids, Sabtoron and Violetta, were as highly productive and persistent as the three tetraploids but in the sixth year the decrease in productivity was greater in the diploids than in the tetraploids. In the fifth year Teroba, the highest yielder, produced 9 8 t total DM ha
The trial demonstrates the potential of a number of red clover cultivars grown either pure or with a suitable perennial grass to achieve and maintain a high output of herbage of good quality over a period of 6 years without any application of fertilizer N. The practical agricultural implications of using red clover are discussed. 相似文献
13.
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
14.
High-yielding grass-legume mixtures play an important role in forage-animal systems but finding compatible and adapted species can sometimes be difficult. The objective of this study was to examine productivity of perennial ryegrass and orchardgrass in pure stands with N and in mixtures with legumes.
Broadcast sowings were made on conventionally prepared seedbeds in August 1979 and May 1980 on a Hagerstown silt loam soil (fine, mixed mesic Typic Hapludalf). When sown alone orchardgrass cv. Pennlate and perennial ryegrass cv. Reveille received rates of N ranging from 0 to 448 kg ha−1 a−1 . The grasses were also grown in mixtures with alfalfa cv. Arc, red clover cv. Arlington, or birds foot trefoil cv. Viking. The same legumes were sown alone. Four legume seed rates were used in both the pure legume and mixed stands.
Orchardgrass-N swards were more productive than ryegrass-N swards over 3 years. More dry matter (DM) was harvested from pure stands of 相似文献
Broadcast sowings were made on conventionally prepared seedbeds in August 1979 and May 1980 on a Hagerstown silt loam soil (fine, mixed mesic Typic Hapludalf). When sown alone orchardgrass cv. Pennlate and perennial ryegrass cv. Reveille received rates of N ranging from 0 to 448 kg ha
Orchardgrass-N swards were more productive than ryegrass-N swards over 3 years. More dry matter (DM) was harvested from pure stands of 相似文献
15.
JUNE M. McBRATNEY 《Grass and Forage Science》1987,42(2):147-152
Three diploid red clover cultivars—Sabtoron, Violetta and Essex—and three tetraploid, Hungaropoly, Teroba and Red Head, were sown separately in pure culture and with each of three companion grasses: timothy (Aberystwyth S48), tall fescue (Aberystwyth S170) and perennial ryegrass (Aberystwyth S24).
The effects of fertilizer N on yield and on clover/grass ratio over a 2-year period (seventh and eighth harvest years) subsequent to 6 harvest years during which no N fertilizer was applied were investigated. The data for productivity and persistence have already been published (McBratney, 1981; 1984).
Application of fertilizer N increased DM yields in the eighth year. In this year, the highest yield, 11·9t ha-1 , averaged over the six clover cultivars, was given in association with tall fescue. Tall fescue contributed 90% of this yield. Clover content continued to decrease in all swards but the decrease was greatest in the swards receiving fertilizer N. The yield of clover DM averaged over the six cultivars under N treatment declined from 5·6t ha-1 in the seventh year to only 0·4t ha-1 in the eighth year.
The results from this trial demonstrate the potential of red clover sown either pure or in mixture with a suitable perennial grass, to maintain high output of quality herbage over a 6-year period without the aid of fertilizer N. They further demonstrate that following decline in red clover content, both herbage yield and quality may be restored by the application of N fertilizer, particularly where the clover was seeded with a highly productive companion grass. 相似文献
The effects of fertilizer N on yield and on clover/grass ratio over a 2-year period (seventh and eighth harvest years) subsequent to 6 harvest years during which no N fertilizer was applied were investigated. The data for productivity and persistence have already been published (McBratney, 1981; 1984).
Application of fertilizer N increased DM yields in the eighth year. In this year, the highest yield, 11·9t ha
The results from this trial demonstrate the potential of red clover sown either pure or in mixture with a suitable perennial grass, to maintain high output of quality herbage over a 6-year period without the aid of fertilizer N. They further demonstrate that following decline in red clover content, both herbage yield and quality may be restored by the application of N fertilizer, particularly where the clover was seeded with a highly productive companion grass. 相似文献
16.
The productivity of four forage legumes sown alone and with each of five companion grasses 总被引：1，自引：0，他引：1
Four legumes—white clover cv. Blanca, red clover cvs Violetta (diploid) and Hungaropoly (tetraploid) and lucerne cv. Europe—were established as pure-sown swards and with each of five companion grasses: timothy cv. Timo, meadow fescue cv. Bundy, sweet brome cv. Deborah and perennial ryegrass cvs Talbot (diploid) and Barlatra (tetraploid), both ryegrasses being of 'intermediate' heading date. Two 'silage' crops and an 'aftermath grazing' crop were harvested in each of three successive years.
In the first harvest year, total herbage DM production of red clover ranged from 15·03 to 17·01 t ha-1 . White clover and lucerne swards produced considerably less at 7·12 to 11·01 t ha-1 . In the second harvest year, lucerne swards were the highest producing at 15·54 to 17·14 t ha-1 , while DM production from red clover and white clover swards ranged from 6·75 to 11·87 t ha-1 . Lucerne swards maintained their production superiority in the third year at 16·48 to 17·87 t ha-1 , while production from white clover swards ranged from 6·41 to 10·23 t ha-1 . However, red clover swards declined to 3·30 to 5·81 t ha -1 ; this above-average decline was mainly caused by the onset of red clover necrotic mosaic virus which affected all red clover plots uniformly in the second harvest year, and by winter conditions before the third harvest year. Total herbage DOM and CP yields of the swards were influenced in a similar manner to DM production. 相似文献
In the first harvest year, total herbage DM production of red clover ranged from 15·03 to 17·01 t ha
17.
The effect of some invertebrate species on persistence of white clover in ryegrass swards 总被引：1，自引：0，他引：1
In two experiments in established swards of perennial ryegrass and white clover, plots were treated with pesticides to control slugs, leather-jackets, weevil larvae and lucerne flea as selectively as possible. Other plots were treated to control ail of these pests.
Chlorpyrifos application in early summer (to control weevil larvae) and methiocarb pellets (to control slugs) also gave partial control of leather-jackets. Other effects on non-target species were considered to be unimportant, as pest status could not be attributed to the species. A high level of control of lucerne flea by methiocarb pellets, noted previously, was confirmed.
At both sites combined treatment against insect pests and slugs produced large increases in clover content and yield over a 3-year period, in comparison with untreated plots, although clover tended to decline In alt plots. At one site, where the clover content of untreated plots reached 33% at one stage, specialist clover herbivores such as weevils and lucerne flea were more common. Treatments directed against weevils and slugs gave the highest clover yields, and leatherjacket control may also have contributed, particularly when the population reached 0.9 m ha−1 in the final year. At the other site, where the clover content was low (ultimately 01.1–6%), leather-jacket populations reached 2.1 m ha−1 and slug numbers were also relatively high. Control of these species contributed most to the relative increase in clover content and yield. 相似文献
Chlorpyrifos application in early summer (to control weevil larvae) and methiocarb pellets (to control slugs) also gave partial control of leather-jackets. Other effects on non-target species were considered to be unimportant, as pest status could not be attributed to the species. A high level of control of lucerne flea by methiocarb pellets, noted previously, was confirmed.
At both sites combined treatment against insect pests and slugs produced large increases in clover content and yield over a 3-year period, in comparison with untreated plots, although clover tended to decline In alt plots. At one site, where the clover content of untreated plots reached 33% at one stage, specialist clover herbivores such as weevils and lucerne flea were more common. Treatments directed against weevils and slugs gave the highest clover yields, and leatherjacket control may also have contributed, particularly when the population reached 0.9 m ha
18.
Herbage characteristics were studied over years 4–6 (1988–90) in three perennial ryegrass ( Lolium perenne L.) varieties as grass-only (200 kg N ha-1 ) and grass/clover ( Trifolium repens L.) swards which received 75kg N ha-1 in 1988 and 0kg N ha-1 in 1989 and 1990 when continuously stocked with sheep. Mean total annual herbage production of Aurora, a very early flowering variety, was 11% more than that of late-flowering Aberystwyth S23 due to 21% higher growth as grass/clover pasture. The grass/clover sward of Meltra, a tetraploid late-flowering variety, out-yielded S23/clover by 17%. Herbage production of grass/clover was 86% of that of grass only in 1988 but only 54% of the grass-only swards averaged for 1989 and 1990.
In vitro organic matter digestibility (OMD) of Meltra was 38g kg-1 OM and 27g kg-1 OM higher than that of S23 and Aurora respectively. OMD of grass/clover was 15g kg-1 OM higher than that of grass only during the post-weaning period. Herbage intake was positively correlated with OMD of herbage.
The herbage attributes were related to lamb performance reported previously. Lamb output was positively correlated with intake of digestible organic matter.
Differences between the three varieties in herbage characteristics were greater as grass/clover than as grass-only swards, reflecting their compatibility with white clover. In this respect Meltra was the best and S23 the poorest variety. 相似文献
In vitro organic matter digestibility (OMD) of Meltra was 38g kg
The herbage attributes were related to lamb performance reported previously. Lamb output was positively correlated with intake of digestible organic matter.
Differences between the three varieties in herbage characteristics were greater as grass/clover than as grass-only swards, reflecting their compatibility with white clover. In this respect Meltra was the best and S23 the poorest variety. 相似文献
19.
This study evaluated the relationships between legume proportion and dry matter (DM) yield, N yield, and herbage N concentration for three binary legume-grass mixtures In Uruguay. Two identical trials were established, one in 1983 (Trial 1) and another in 1984 (Trial 2) and were evaluated for 2 years. Treatments were white clover ( Trifolium repens L.) (WC), red clover ( Trifolium pratense L.) (RC), and birds-foot trefoil ( Lotus corniculatus L.) (BT), each grown with tall fescue ( Festuca arundinacea Schreb. ) (TF) at four legume proportions, plus pure stands of TF. In Trial 1, annual DM yields of RC-TF were greater than yields of WC-TF or BT-TF and in Trial 2 RC-TF and BT-TF yielded more than WC-TF. The N concentration of either the legume or TF components usually was greater for WC-TF than other mixtures in both trials. Annual DM yields in Trial 1 were optimized by legume proportions of 47 to 59% for WC, 62 to 67% for RC-TF, and 57 to 100% for BT-TF; and N yields were optimized by 70% of WC or RC, and by 100% BT. In Trial 2, which had greater soil-N availability than Trial 1, optimum DM or N yields were achieved at lower WC proportions than in Trial 1. Changes in legume proportion did not affect legume N concentrations, but N concentration of TF in mixture was always positively and linearly related with legume proportion. It is concluded that DM yields for the first 2 years after seeding were greater for RC-TF and BT-TF than for WC-based mixtures. Herbage DM and N yields of WC-TF were optimized by lower legume proportions than for RC-TF and BT-TF. The N concentration of TF increased linearly with increasing proportions of any of the three legumes. 相似文献
20.
Herbage characteristics were monitored over 3 years (1985–1987) in three perennial ryegrass ( Lolium perenne L.) varieties as grass/only (200 kg N ha−1 ) and grass/clover ( Trifolium repens L.) (75 kg N ha−1 ) swards when continuously stocked with sheep. Although mean total annual herbage production was similar from the grass varieties, growth of Aurora, a very early-flowering variety, was higher than that of Aberystwyth S23 and Meltra (tetraploid) late-flowering types in spring. Herbage production from grass-only swards was 15% higher than from grass/clover swards.
In vitro organic matter digestibility (OMD) of Aurora and Meltra was 34 g kg−1 and 26 g kg −1 higher ( P < 0·01) than that of S23. Averaged over varieties, the OMD of grass/clover was 25 g kg −1 higher ( P < 0·05) than grass-only during the post-weaning period. Individual lamb digestible organic matter intake (DOMI) was 22% higher ( P < 0·05) on grass/clover than on grass-only during this period. Water-soluble carbohydrates content of Aurora was 42% higher ( P < 0·001) than that of both Meltra and S23.
Herbage characteristics were related to lamb performance reported previously. Lamb production was positively correlated with DOMI. However, the magnitude of differences in lamb performance between treatments was much greater than the extent of differences detected in herbage characteristics. 相似文献
In vitro organic matter digestibility (OMD) of Aurora and Meltra was 34 g kg
Herbage characteristics were related to lamb performance reported previously. Lamb production was positively correlated with DOMI. However, the magnitude of differences in lamb performance between treatments was much greater than the extent of differences detected in herbage characteristics. 相似文献