Evaluation of performances of a legume Chamaecrista rotundifolia to improve natural pastures in semi-arid ecosystems.

Amélioration des pâturages naturels par sursemis de légumineuses Chamaecrista rotundifolia

Abstract

This study aims to improve the natural pastures dominated by Andropogon gayanus by overseeding a  legume, Chamaecrista rotundifolia. The experimental design is randomized complete blocks with three  studied factors: sowing mod (weeding and unweeding the existing grasses), seeding density (control, 200  and 400 plants of forage legume/m²) and triple superphosphate application (0 and 100 kg/ha). Results  showed that the numbers of plants of introduced fodder legume established in the stand was far less than  expected ’10 to 155 plants/m²). Phosphorus application doesn’t affect this number but the sowing mod  influenced this significantly. Weeded plots had higher number of legume plants/m² than un-weeded.  Phosphorus application improved significantly biomass production on the ferralitic soil compared to the  ferruginous soil. The percentage of C. rotundifolia in the total biomass ranged from 15 to 95% and 6 to  94% for ferralitic and ferruginous soil, respectively. In weeded plots, the average percentage of C.  rotundifolia in the total biomass was better (75%) than in the non-weeded plots (15%). Similarly, the  seeding density of C. rotundifolia at 400 plants/m² resulted in 57% part of C. rotundifolia compared to  47% in plots seeded at 200 plants/m² and 30% in the control plots. Seeding density of 200 plants/m²  associated with phosphorus application could be recommended for natural pasture improvement by  overseeding C. rotundifolia on ferralitic soil type.