Author
 |
Belesky, David |
|
Fedders, James |
|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/28/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Legumes are important sources of biologically fixed nitrogen for pasture systems. Grazing animals benefit from legumes through increased protein, minerals, and other compounds. Farmers often experience difficulty in maintaining the highly desirable legume component of grazed pastures. We conducted grazing studies to determine the effects of autumn grazing practices on productivity and persistence of legumes in mixed pastures. Complete use of pasture in autumn had favorable effects upon legume development and persistence. Overall pasture productivity was not affected; however, pasture quality was improved by increasing the amount of legume relative to other plants in pasture. Our findings show that farmers can maintain and improve the legume component of pasture by completely using autumn accumulated herbage. Nitrogen fertilizer inputs would be reduced and animal production efficiency increased. Technical Abstract: Autumn grazing management may affect the balance of grasses and legumes in a sward; consequently, productivity and morphology of an orchardgrass (Dactylis glomerata, L.) and white clover (Trifolium repens, L.) dominated sward as influenced by duration of grazing intervals in autumn was investigated. Exclosures were located in each of nine paddocks to provide undisturbed canopies. Pastures were grazed by weaned lambs (Ovis spp.) beginning in August of each of three years. Three replicate paddocks were closed to grazing after 30, 60, or 90 days. Grazed paddocks were sampled at two week intervals to determine herbage mass, botanical composition, and nonstructural carbohydrates content of grass and legumes. Early-close paddocks continued to accumulate herbage during autumn, resulting in greater winter senescence than in late-close paddocks. Spring cut herbage mass was not affected by autumn management. Botanical composition of herbage harvested as hay in spring was affected in that late-close paddocks had significantly more clover than did early-close paddocks. Early-close paddocks were dominated by grass plants that had relatively few large tillers and by white clover plants that had fewer growing points than those in late-close paddocks. Late-close paddocks had twice as many clover growing points as did early-close paddocks. Stolon mass was greater, but starch and nonstructural carbohydrate content were less during autumn in late- than in early-close paddocks. A delicate balance between growing points and TNC may be involved in long-term clover presence in mixed swards. Clover persistence in mixed swards may be favored by grazing throughout autumn. |
