Grasses Forages in Farming Systems

186 Beef Breeder MANUAL michelianum, and annual medics Medicago spp. in improved pastures, and local evaluation is required to assess their potential.

9.2.4. Grasses

Grasses form the bulk of grazing pastures worldwide. A considerable efort has been expended to develop improved cultivars of successful and adapted grasses across the great range of environments where livestock are grazed. However, unlike legumes, grasses are not able to obtain nitrogen to support their growth from the atmosphere and must therefore rely on soil sources of nitrogen to support their protein requirements for growth. As a consequence, the productivity of grass based pastures is primarily limited by nitrogen availability, since most soils are incapable of supplying suicient nitrogen from soil-derived sources to support the Table. 9.3. Common perennial legumes suited to most winter climates, and their tolerance to drought, and soil acidity and alkalinity. Adaptation of these species to local conditions is dependent on annual rainfall and requires local validation. Source: Forage Adaptation; Manitoba Agriculture, Food and Rural Development. growth potential of the grass. This is particularly evident wherever selected and improved grass species and cultivars are sown with the view to establish highly productive pastures for grazing. In countries with cold climates, grasses that are sown for use in pastures for grazing animals are typically perennial species that persist for a number of years under ideal growth and grazing conditions Table 9.4. Although some annual grasses are sown in these areas as specialist forages for conservation and feeding to animals during winter, for example millet Echinochloa utilis and sorghum Sorghum bicolor, the potential exists to utilise a range of other annual or biennial grasses such as ryegrass Lolium multiflorum, Lolium rigidum in improved pastures for either seasonal grazing or fodder conservation. Adoption of these species requires local evaluation to assess their potential. Common Name Scientiic Name Winter Hardiness Drought Tolerance Acidity Tolerance Alkalinity Tolerance Alfalfa Purple flower Yellow flower Medicago sativa ssp. sativa ssp. falcata Good Good Good Good Low Low High High White Clover Trifolium repens Good Poor Moderate Moderate Sainfoin Onobrychis vicifolia Moderate Good Low High Sweet Clover Melilotus albus Moderate High Low Moderate Alsike Clover Trifolium hybridum Moderate Poor Moderate Moderate Red Clover Trifolium pratense Poor Low Moderate Moderate 187 Cold Winter Climates

9.2.5. Selecting the Right Species