抄録
To show the cause of lower grassland productivity at the early stage of tropical legume/grass mixture system, yields of dry matter and nitrogen and the magnitude of mixture effect on increasing dry matter production were investigated for two years with the mixed stand of Desmodium intortum cv. Greenleaf (De) and Setaria anceps cv. Kazungula (Ks) and the pure stands of De and Ks. Results obtained are as follows: 1) Dry matter yields in the mixed stand were higher in the second year than in the first year. 2) Nitrogen contents in De increased after the second harvest while those in Ks increased with later harvests. Nitrogen yields were, in the decreasing order, the pure stand of De, followed by the mixed stand and the pure stand of Ks. 3) Mixture effect significantly increased in the second year, especially in Ks component. These results were discussed in relation to nitrogen transfer from the legume to the grass. It was concluded that lower grassland productivity at the early stage of the sward establishment was due to longer periods required for the begining of active nitrogen fixation by the legume and of nitrogen transfer from legumes to the grass. Application of starter nitrogen was suggested for a means of increasing grassland productivity at the early stage of the grassland establishment.
