Publication Date
1989
Description
The lower productivity of legume based swards and their instability of yield from year to year compared with nitrogen fertilised grass swards continues to be a major constraint on the integration of leguminous nitrogen fixing species into present-day farming systems. Most legume systems have a high biological nitrogen fixation (BNF) potential which is rarely attained in the· field due to limiting environmental or management factors. Enhancement of BNF through manipulation of the Rhizobium and plant components of the symbiosis must be viewed as a long-term objective. Optimisation of nitrogen fixation in the short-term may best be achieved through optimisation of environmental/management conditions most conducive to legume performance in the field. Information on the fate oflegume fixed nitrogen is much less precise than that available on nitrogen inputs via BNF. The transfer of legume nitrogen in situ to companion grasses in the sward or as legume derived soil nitrogen residues for succeeding crops following plough-down is not predictable with many environmental factors such as soil temperature affecting the process. As most legume swards are grazed there is further potential for transfer of fixed nitrogen to companion grasses in the sward via dung and urine. Compared with grass swards receiving high inputs of nitrogenous fertilisers, legume based swards are less leaky for nitrogen and more environmental friendly both in terms of having less animal consumed nitrogen excreted in urine and less nitrogen losses from the soil through volatilisation, leaching and denitrification processes.
Citation
Demarquilly, C, "The Feeding Value of Forages" (1989). IGC Proceedings (1985-2023). 3.
(URL: https://uknowledge.uky.edu/igc/1989/openingspeeches/3)
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
The Feeding Value of Forages
The lower productivity of legume based swards and their instability of yield from year to year compared with nitrogen fertilised grass swards continues to be a major constraint on the integration of leguminous nitrogen fixing species into present-day farming systems. Most legume systems have a high biological nitrogen fixation (BNF) potential which is rarely attained in the· field due to limiting environmental or management factors. Enhancement of BNF through manipulation of the Rhizobium and plant components of the symbiosis must be viewed as a long-term objective. Optimisation of nitrogen fixation in the short-term may best be achieved through optimisation of environmental/management conditions most conducive to legume performance in the field. Information on the fate oflegume fixed nitrogen is much less precise than that available on nitrogen inputs via BNF. The transfer of legume nitrogen in situ to companion grasses in the sward or as legume derived soil nitrogen residues for succeeding crops following plough-down is not predictable with many environmental factors such as soil temperature affecting the process. As most legume swards are grazed there is further potential for transfer of fixed nitrogen to companion grasses in the sward via dung and urine. Compared with grass swards receiving high inputs of nitrogenous fertilisers, legume based swards are less leaky for nitrogen and more environmental friendly both in terms of having less animal consumed nitrogen excreted in urine and less nitrogen losses from the soil through volatilisation, leaching and denitrification processes.
