Abstract
The effects of NH_4-N, NO_3-N, and NH_4NO_3-N on seedling growth, nodule formation, symbiotic N_2-fixation, and mineral-N assimilation of Desmodium intortum cv. Greenleaf were investigated under controlled conditions. The rate of mineral-N application influenced the DM yield but the form of mineral-N did not. As N rates increased, total nodule number and weight were positively affected with NH_4-N but not with NO_3-N. Weight per nodule increased with higher rates of NO_3-N but not with NH_4-N application. Plant N from symbiotic N_2-fixation increased linearly with NH_4-N, and decreased with NO_3-N application. N originating from mineral-N increased linearly with increasing rates of N application in the following order ; NO_3-N>NH_4NO_3-N>NH_4-N. The data reveal that NH_4-N is a better source of N for starter N.
