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1.
Grazing lands in warm‐temperate and subtropical North America have become less diverse. Pastures are typically grass monocultures, while rangelands are generally managed for the grass components. Overstocking, selective herbicides, fire exclusion and heavy rates of nitrogen fertilizer have contributed to near exclusion of native, warm‐season legumes. The simplicity of managing grass monocultures, pasture production responses to nitrogen fertilizer and profitability of grass‐only systems have limited interest in legume‐based approaches. Changing economics and ecological concerns with ecosystem accumulation of industrial inputs contribute to an increasing interest in legumes. Unlike the development of temperate pasture legumes and recent research in the tropics, legumes tolerant of both freezing temperatures and hot weather have received less attention. Poor establishment, limited persistence and potential invasiveness limit currently available introduced species. Native, herbaceous, warm‐season legume species occur throughout warm‐temperate North America, but little attention has been directed to these plants as potential forage species. Some success with a few native legume species, primarily in the genus Desmanthus, suggests potential for expanded assessment of forage value of the many species available. Current assessments of native legumes, primarily for conservation purposes, provide an opportunity to expand evaluations of these species for pasture and rangeland potential while economics of livestock production and public interest in ecosystem health are supportive. Experiences with legumes of warm‐temperate origin in North America, along with results with temperate and tropical pasture legumes globally, provide a starting point for future efforts at incorporating greater legume diversity in pastures and rangelands of subtropical and warm‐temperate regions around the world.  相似文献   

2.
Forage legumes are vitally important to animal production in the dryland farming systems of the Mediterranean region. Of the diverse forage‐legume species adapted to the Mediterranean climate, vetches, (Vicia spp.), chicklings (Lathyrus spp.), annual medics (Medicago spp), clovers (Trifolium spp.) and species of the Lupinus, Lotus, Onobrychis, Hedysarum and Ornithopus genera are considered to be the most agronomically important and economically valuable species for the region. Adoption of perennial self‐regenerating medic (Medicago spp.) has been limited because of technical difficulties, but annual vetch (Vicia spp.) has the greatest potential as a viable animal‐feed source and a rotation crop with cereals. Some forage legumes survive harsh conditions by their unique underground growth habit, for example, V. amphicarpa and Lathyrus ciliolatus. Efforts to improve forage legumes have been based on both management/cultural factors and breeding. Research based on several long‐term barley‐ and wheat‐based rotation trials has demonstrated the viability of forage legumes, especially vetch, in the region's improved farming system. An additional benefit to such legumes is the enhancement of soil quality, that is, soil fertility, soil organic matter and soil physical properties. Thus, the development of forage legumes is essential to agricultural sustainability in the Mediterranean region and in other dryland cereal‐growing areas of the world where grazing livestock is a dominant enterprise. To build upon the considerable research conducted on forages, intensified efforts are needed to develop locally adapted forage cultivars, to provide economic assessment of forages in cropping systems and to promote technology transfer at the farm and community level.  相似文献   

3.
Seasonal changes in herbage mass and herbage quality of legume‐based swards under grazing by sheep or cattle were investigated at four locations in climatically different zones of Europe: Sardinia (Italy), southern France, northern Germany and south‐west England (UK). At each location standard treatments were applied to legumes typical of species widely used in each locality: Medicago polymorpha in Italy, Medicago sativa in France, and Trifolium repens in Germany and in UK. At each site comparisons were made of two other legumes: Trifolium subterraneum and Hedysarum coronarium in Italy, Onobrychis sativa and Trifolium incarnatum in France, Trifolium pratense and Lotus corniculatus in Germany, and Trifolium ambiguum and L. corniculatus in UK. Legumes were sown in mixture with locally appropriate companion grasses, and measurements were made over two or three grazing periods. In Italy M. polymorpha swards gave the greatest herbage mass in grazing period 1 but H. coronarium was more persistent. At the French site all legumes established poorly with no significant herbage mass differences between treatments. At both the UK and German sites L. corniculatus maintained a high proportion of legume in the sward; T. repens showed poor persistence under continuous sheep grazing in UK but persisted under cattle grazing in Germany, while T. ambiguum was slow to establish in the UK, and T. pratense proved to be of comparable herbage mass to the standard T. repens‐based sward in the last year of the experiment. The concentration of crude protein and in vitro digestibility of organic matter in the dry matter of herbage showed greater within‐season variation than between treatments at each site. It is concluded that, in addition to currently used species, legume‐based swards containing H. coronarium, O. sativa and L. corniculatus all have potential to contribute to forage production for low‐input grazing and their use merits further consideration in systems of livestock production in Europe.  相似文献   

4.
Based on experimental data gathered in a research project on nitrogen fluxes in intensive dairy farming in Northern Germany, an analysis of fossil energy input and energy efficiency in forage production from permanent grassland and maize for silage was conducted. Field experiments comprised different defoliation systems and different rates of mineral N fertilizer and slurry application. Each change from grazing to cutting in grassland systems reduced the energy efficiency. Energy efficiency consistently decreased with increasing rates of mineral N application. In the production of maize for silage, maximum energy efficiency was obtained with an application of 50 kg N ha?1 from slurry only. Net energy yields of maize for silage were much higher than that of grassland when compared at the same level of fossil energy and nitrogen fertilizer input. Considering both nitrate‐leaching losses and a necessary minimum quantity of grass herbage in a well‐balanced ration, it is suggested that a high proportion of maize for silage in combination with N‐unfertilized grass/clover swards used in a mixed cutting/grazing system represents a good trade‐off between the leaching of nitrates and energy efficiency.  相似文献   

5.
A meta‐analysis was performed to determine the effects of feeding ruminants with tropical legume silages on intake, digestibility and performance using a data set with 218 treatments (162 containing legumes, 56 without legumes) from 62 trials. First, a regression analysis was performed for diets containing legumes. Dry‐matter intake (DMI) and digestibility decreased with increasing legume proportion, with greater effects on large compared with small ruminants. Milk yield (MY) by dairy cows was not affected by legumes. Average daily gain (ADG) by cattle was maximized with legume silage inclusion between 200 and 400 g/kg DM, but no effect appeared for small ruminants. A second analysis compared diets without legumes with diets with medium (101–400 g/kg DM) and high (401–800 g/kg DM) legume inclusion. There were no differences in DMI, MY and ADG between the medium inclusion and without legumes, but all these parameters decreased with high inclusion. Digestibility was lower in diets with legume silages than in diets without legumes, regardless of the inclusion level. Feed conversion efficiency (FCE) was highest in diets with medium inclusion and lowest with high legume inclusion. While high legume inclusion negatively affected performance, including legume silages up to 400 g/kg DM seems to enhance or at least maintain MY, ADG and FCE, despite lower intake and digestibility. The reasons for such apparent paradox remain unclear. Well‐designed studies focusing on, e.g. microbial protein synthesis, energy metabolism, protein/carbohydrates characteristics, are required to better understand the effects of tropical legumes silages on nutrients’ utilization.  相似文献   

6.
In pasture‐based dairy farming, new sustainable systems that involve the annual dry matter (DM) production of grazed and conserved forage beyond the potential of grazed pasture alone are being sought. The objective of this experiment conducted in Australia was to compare a complementary forage rotation (CFR) for conservation and grazing, comprising an annual sequence of three crops, namely maize (Zea mays L), forage rape (Brassica napus L) and a legume (Persian clover, Trifolium repesinatum L or maple pea, Pisum sativum L), with a pasture [kikuyu grass (Pennisetum clandestinum) over‐sown with short‐rotation ryegrass (Lolium multiflorum L)] as a pasture control treatment. The experiment was a complete randomized block design with four replicates (~0·7 ha each). Annual dry‐matter (DM) yield over the 3 years averaged >42 t ha?1 year?1 for the CFR treatment and >17 t ha?1 year?1 for the pasture treatment. The high DM yield of the CFR treatment resulted from >27 t ha?1 year?1 from maize harvested for silage and >15 t DM ha?1 year?1 utilized by grazing the forage rape and legumes. Total input of nitrogen (N) and water were similar for both treatments, resulting in higher N‐ and water‐use efficiency for the CFR treatment, which was more than twice that for the pasture treatment. Overall, the nutritive value of the pasture treatment was slightly higher than the mean for that of the CFR treatment. The implications of these results are that a highly productive system based on the CFR treatment in conjunction with the use of pasture is achievable. Such a dairy production system in Australia could increase the total supply of feed resources grown on‐farm and the efficiency of use of key resources such as N and water.  相似文献   

7.
Production of grass and fodder crops in areas under intensive production systems in the Low Countries of north‐west Europe faces a number of threats related to increased regulations, scarcity of land and restricted freedom of use of the land, and from climate change. Grassland‐based farmers are pushed to do more with less, i.e., to improve eco‐efficiency, and this requires “more knowledge per ha.” This article argues that progress in variety breeding, the application of crop rotation instead of monocultures, a proper use of catch crops, ley‐arable farming and overall good management offer realistic opportunities to cope with current threats. A large capacity for mechanization also allows improvement of net yields per ha. This article highlights that progress in plant breeding has compensated for yield declines caused by nutrient‐input restrictions in forage maize (Zea mays L.). Both forage maize and grass–clover can take advantages of ley‐arable farming, and crop rotation provides an insurance against the effects of low‐yielding years and a buffer for reduced nutrient inputs.  相似文献   

8.
A 21-acre grazing trial which ran continuously for three years to evaluate grass and grass/legume pasture with and without inorganic fertilizers is described. Techniques for conducting grazing trials where large treatment differences are expected and the interpretation of results from these trials are discussed. Good practical management of stock and pastures was shown to be necessary in these grazing trials and where it was only possible to establish one true replicate some measure of statistical control was achieved by comparing regression coefficients of cumulative animal production.
The results showed that up to 475 1b liveweight gain/acre per annum (532.48 kg/ha) could be obtained from pastures grazed by small East African Zebu steers. The addition of the legumes Stylosanthes gracilis and Centrosema pubescens to grass mixtures gave significant and economic increases in liveweight gain. Grass/legume swards receiving phosphorus and sulphur produced liveweight gains equivalent to the animai production from grass swards receiving 140 1b N/ac per annum (156.94 kg/ha).  相似文献   

9.
Beef cattle producers seldom use fertilizers for their pastures in tropical regions of Brazil. Slowly, this is changing but because of the need for repeated applications, N fertilizer is rarely applied. The introduction of a forage legume is an appropriate solution for this problem, but until recently adoption has been very low as the legumes generally have not persisted in the sward. We report research on how grazing management can affect the persistence of stoloniferous legumes in pastures of Brachiaria spp. and the problems of establishing and maintaining crown-forming legumes such as Stylosanthes spp. With suitable management, milk or bovine carcass yields can be equal or greater from mixed than from grass-alone pastures fertilized with 120 or 150 kg Nha-1 year−1. In addition to savings in CO2 emissions from fossil fuels for the production and distribution of N fertilizers, nitrous oxide emissions from cattle excreta and legume residues are lower than those from N-fertilized brachiaria grass monocultures. Other studies indicate that enteric methane emissions from cattle may be mitigated when forage legumes are included in their diet. The use of forage legumes in mixed pastures for tropical regions is emerging as a feasible strategy to keep meat and milk production at acceptable levels with reduced greenhouse gas emission rates.  相似文献   

10.
In grass–legume swards, biologically fixed nitrogen (N) from the legume can support the N requirements of the grass, but legume N fixation is suppressed by additional fertilizer N application. This study sought to identify a fertilizer N application rate that maximizes herbage and N yields, N fixation and apparent N transfer from white clover to companion grasses under intensive grazing at a site with high soil‐N status. During a 3‐year period (2011–2013), swards of perennial ryegrass and of perennial ryegrass–white clover, receiving up to 240 kg N ha?1 year?1, were compared using isotope dilution and N‐difference methods. The presence of white clover increased herbage and N yields by 12–44% and 26–72%, respectively. Applications of N fertilizer reduced sward white clover content, but the effect was less at below 120 kg N ha?1. The proportion of N derived from the atmospheric N fixation was 25–70%. Nitrogen fixation ranged from 25 to 142 kg N ha?1 measured using the isotope dilution method in 2012 and from 52 to 291 kg N ha?1 using the N‐difference method across all years. Fertilizer N application reduced the percentage and yield of fixed N. Transfer of N from white clover to grass was not confirmed, but there was an increased N content in grass and soil‐N levels. Under intensive grazing, the maximum applied N rate that optimized herbage and N yields with minimal effect on white clover content and fixation rates was 60–120 kg N ha?1.  相似文献   

11.
《Journal of Crop Improvement》2013,27(1-2):187-216
SUMMARY

Perennial and annual forage legumes are important components of sustainable cropping systems. Forage legumes are a primary source of forage to supply protein and fiber for livestock rations. They can be grazed, or stored as hay or silage. They contribute biologically fixed N and sustain the soil by reducing erosion and increasing soil organic matter levels. Diversifying cropping systems by including legumes can also reduce weed, insect, and disease incidence. Potential new uses of legumes include phytoremediation of N contaminated sites and capturing N lost from cropping systems. Legumes also have potential use as a feedstock for renewable energy production. Legumes have traditionally been used in rotation with grain crops but more recently have been shown promise as winter cover crops, intercrops with grain crops, and as living mulches. In this review, we discuss traditional and new roles of forage legumes in sustainable cropping systems with examples primarily chosen from northern USA and Canada.  相似文献   

12.
Perennial forage legumes, particularly lucerne (Medicago sativa L.), play a significant role in crop/livestock mixed farming systems in the semiarid region of the Loess Plateau of China as stock feed and a source of nitrogen for subsequent crops. However, there is evidence that lucerne reduces soil water deep in the soil profile, thereby reducing subsequent crop productivity. From 2004 to 2010, this study evaluated the forage productivity and water use of two locally adapted perennial legume species, milk vetch (Astragalus adsurgens Pall.) and bush clover (Lespedeza davurica S.), compared with lucerne. The 7‐year total and average annual forage yield of milk vetch were 56 and 8 t ha?1 and bush clover was 42 and 6 t ha?1, respectively, significantly lower than lucerne at 91 and 13 t ha?1. However, despite lower water‐use efficiencies (16 and 12 kg ha?1 mm?1 for milk vetch and bush clover, respectively, compared to 22 kg ha?1 mm?1 for lucerne), the total 7‐year water use in milk vetch and bush clover was 3500 mm and 3490 mm, respectively, which was 135–140 mm less than lucerne. After 7 years, lucerne had extracted water from the upper 5 m soil, whereas bush clover used water mainly from the upper 2 m of the soil profile and milk vetch still had some water available below 3 m. We conclude that while the locally adapted forage legumes were not as productive as lucerne as a source of fodder in mixed cropping/livestock system in this region, they use less water, which may be advantageous in drier regions.  相似文献   

13.
Nitrogen is an essential macro-nutrient for plant growth and is indispensable for high agricultural food productivity and quality. Shortage of good quality forage under the dry winter season and low soil fertility conditions are the major constraints in rural farming systems in the Moist Tall Grassveld of the Upper Thukela, South Africa. The effect of legumes on inorganic soil nitrogen was assessed in an agroforestry trial (Leucaena leucocephala (Lam.) De Wit, Acacia karroo Hayne, Dactylis glomerata L., Festuca arundinacea Schreb.), by soil sampling method. In the agroforestry trial, total inorganic soil nitrogen accumulation was significantly greater under intercropping than under sole crop treatments and, irrespective of the treatments, significantly more nitrate than ammonium nitrogen was measured. The study demonstrated that intercropping grasses with tree legumes could provide important ecosystem services of nitrogen supply in the soil. The results suggested that introducing legume intercrops might constitute a relevant cropping strategy to improve the soil fertility status with regard to nitrogen while at the same time providing forage in smallholder farming systems in South Africa’s Moist Tall Grassveld regions.  相似文献   

14.
The concept is presented of combined cultivation of legumes and sorghum–maize and their use as conserved ruminant feed in tropical regions, with special reference to Cuba. Good yields are obtained during the rainy season through intercropping (alternate rows of either sorghum or maize and soybean). When followed by ensiling, this provides high‐quality ruminant feed for the tropical dry season. Soybean compensates for the low crude protein content of sorghum, whereas sorghum allows good silage quality in combination with legumes. The paper reviews and updates recent studies assessing combined sorghum–soybean cultivation and ensiling as well as determination of their feed value. The high nutritive quality and forage potential when these crops are intercropped demonstrate that silage from these plants can be used successfully in ruminant diets in Cuba and other tropical areas. Perspectives for new studies in this field are suggested, particularly with legume species that are more adapted to specific tropical regions and/or with higher forage yield. In addition, it is suggested that there is a need to assess the supplementation impact on meat and milk production at the farm level, as well as its environmental impact, when ruminants are fed combined silages from whole plants of sorghum–legumes.  相似文献   

15.
A pre‐existing mechanistic model of grass growth, developed to simulate grass production in the UK, was extended to include a variety of grass–legume mixtures and used to predict comparative yields across a range of sites in northern Europe, using experimental data from a series of experiments at fifteen sites. Specifically, predictions were made of the comparative yields of grass (Lolium perenne L.), white clover (Trifolium repens L.), red clover (T. pratense L.), lucerne (Medicago sativa L.), lotus (Lotus corniculatus L.) and galega (Galega orientalis Lam.). The results indicated that the model could generate simulated differences in yields between forage crops, which accorded with observed rankings. However, the predictions were more accurate for total yields than individual cuts, for a country than for an individual site, and for monocultures than for grass–legume mixtures. Nevertheless, the results appeared sufficiently robust to be used to prepare forecasts of yield productivity in different agro‐climatic zones in northern Europe. Using estimates of the production costs and economic values for the forages, it was also possible to assess their comparative profitability. The study indicated that red clover, whether grown singly or in a mixture with grass economically outperformed all silage systems based on pure grass swards, even those receiving 400 kg N ha?1. White clover and lucerne were also consistently more profitable than grass‐based systems, receiving 200 kg N ha?1. In relative terms, lucerne appeared to be more profitable in the south and east of the region, while white clover outperformed lucerne in the north and west. In the north and east of the region, there was some evidence that galega might also hold promise as a silage crop, but lotus was not found to be viable under north European environmental conditions.  相似文献   

16.
Forages are important throughout the south‐east USA for livestock production and wildlife habitat. However, little is known about how forage species commonly grown in this region influence soil‐quality indicators. The objectives of this research were to determine short‐term response of soil water‐stable aggregates (WSA) and density of fungal hyphae (DFH) to: (i) forage species or mixtures grown at identical soil pH levels and (ii) forage species or mixtures grown at field‐state versus adjusted soil pH levels. Nine warm‐season species (sole crop) and eleven cool‐season sole crop or legume–grass mixtures were grown under protected culture in southern coastal plain soil microcosms. Levels of WSA and DFH, and plant shoot and root biomass were evaluated after two 12‐week experimental growth periods in both field‐state and adjusted‐pH soil. Both warm‐ and cool‐season forage species significantly altered short‐term responses of WSA and DFH levels; these responses differed when the soil pH was adjusted from the field state with lime addition. The short‐term responses of both WSA and DFH to lime addition in coastal plain soil were negative only when certain forage species were grown, and no response was detected for the control. It appeared that differences in plant shoot and root developmental characteristics played a key role in soil WSA and DFH responses to the species studied. Further long‐term studies are needed to understand how these relationships are expressed in more variable environments over expanded time frames.  相似文献   

17.
Tall fescue is the main perennial grass of the pastures of the temperate region of Argentina. However, after flowering in spring, tall fescue loses productivity and quality. Based on this, the objective of this work was to evaluate the effects of different post‐grazing mechanical cutting managements on the forage mass, leaf proportion, stocking rate, liveweight gain and liveweight production of tall fescue pastures. The treatments were post‐grazing mechanical cutting at anthesis (FC), post‐grazing mechanical cutting throughout spring and summer (SSC), and no post‐grazing mechanical cutting (NC). The experiment was performed from 2011 to 2014 in Argentina. The greatest and lowest forage mass were determined in September–November and May–September respectively. The leaf proportion of the SSC treatment was greater than that of the NC treatment, except in September–November. NC had higher stocking rate and lower liveweight gain than SSC, and neither NC nor SSC differed from FC. The liveweight production of the treatments was characterized by a trade‐off between stocking rate and liveweight gain. We conclude that FC is an attractive management because, with a single post‐grazing cutting, swards remain productive and leafy.  相似文献   

18.
Despite their ecological, economic and social importance, grasslands in areas with Mediterranean climates continue to receive limited scientific, political and media attention. The main objectives of this review are to compare and contrast dryland grasslands in the ‘Old World’ regions of the Mediterranean basin (southern Europe, western Asia and North Africa) with those of ‘New World’ regions with Mediterranean climates (Australia and Chile) and to identify common research priorities. The common characteristics and differences in climate, soils, native vegetation, importance of the livestock sector and the socio‐economic background for the different Mediterranean environments are examined. Past trends and the current status of temporary and permanent Mediterranean grasslands are also described. Some common issues between these regions are as follows: (i) adaptation to climate change; (ii) increasing persistence and drought survival of both annual and perennial species; (iii) the important role of forage legumes; (iv) maintaining grassland plant diversity; and (v) improved ecosystem services, such as carbon sequestration, control of soil erosion and wildfires, and preservation of both wild and domestic biodiversity. The favourable climate in these regions, which allows year‐round grazing and the growth of legumes, should be exploited to improve the sustainability of grassland‐based, extensive farming systems and the quality of their animal products, while at the same time improving ecosystem services. The decreasing support for grassland research and development programmes requires increased international scientific and technical cooperation among the few institutions operating in the different Mediterranean‐climate areas of the World to provide innovative and sustainable solutions to farmers.  相似文献   

19.
The short life span, irregular forage production and susceptibility to weed colonization of cool‐season grass–legume pastures are serious problems in grazing dairy systems in warm‐temperate regions. The inclusion of warm‐season species has the potential to mitigate these problems. In this study, we evaluated the effect of the inclusion of two warm‐season grasses with different growth habits on seasonal forage biomass, soil cover and weed colonization. Three different pasture mixtures were evaluated under grazing: conventional pasture (CP) [tall fescue (Festuca arundinacea), white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus)], CP with Paspalum dilatatum and CP with Paspalum notatum (CP + Pn). Forage biomass and soil cover were sampled thirteen times during a 3‐year trial, and sampling times were grouped by season for the analyses. The mixtures with Paspalum showed higher soil cover in the autumn, while in the winter CP had higher soil cover than CP + Pn. Competition with tall fescue was similar between mixtures with Paspalum, when considering biomass, but it was higher in CP + Pn when considering soil cover. The inclusion of P. notatum increased biomass during the autumn but decreased the mixture performance during winter by reducing tall fescue soil cover. The addition of a warm‐season grass species with a moderate competing ability like P. dilatatum is likely to avoid a negative impact on the cool‐season component of the pasture.  相似文献   

20.
Ruminant livestock depends primarily on forage and grazing resources from both natural pastures and from cultivated land. Low‐input large‐scale grazing systems constitute a substantial part of what is termed High Nature Value farmland in Europe. Developing a typology of categories of livestock systems within a region is an important step in understanding land uses that involve ruminant livestock systems and their use of feed resources, and in appraising policy options. This study developed a typology based on the municipalities of the region of Aragon in the north‐east of Spain on the basis of the feed resources for ruminant livestock. A clustering analysis was applied to the following three types of criteria: (i) crop types; (ii) vegetation types of uncultivated land and (iii) stocking rate of dairy cattle, beef cattle, sheep and goats. A total of thirty‐nine variables were used. The cluster methodology allowed relatively homogeneous groups of municipalities, termed territories, with differentiating characteristics to be obtained. A Geographic Information System was applied to locate spatially the territories. From the twelve territories identified, it was concluded that there was a low use of natural pastures and high use of resources of cultivated origin in livestock systems in Aragon.  相似文献   

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