INFLUENCE OF TILLAGE AND OVER-SOWING METHODS ON GROWTH, POPULATION DYNAMICS AND BIOMASS YIELD OF TWO STYLOSANTHES SPECIES IN NATURAL PASTURE

Growth, population dynamics and biomass yield of two forage legumes oversown into natural pasture were evaluated. Two legumes ( Stylosanthes guianensis cv. Cook and Stylosanthes hamata cv. Verano), two tillage methods (zero-tillage and minimal tillage) and two sowing methods (broadcast and drill) were combined into eight (8) treatments and replicated 4 times as a 2 × 2 × 2 factorial arrangements in a randomized complete block design. Planting was carried out in late rainy season (September, 2013) and the natural pasture were evaluated for height and canopy/soil cover between 2-8 months after sowing (MAS) which covered the dry and rainy seasons. Evaluation of dry matter yield (DMY) of the sown legumes, dominant grass and other herbaceous species occurred at the onset of rains (May and July, 2014). There were significant differences (p<0.05) in the height of dominant grass, soil covered by sown legumes and other herbaceous species in the dry season. In May, S. guianensis produced higher DMY (9.00 t/ha) with minimal tillage prior to broadcast compared to similar least yields of 4.00 t/ha and 4.25 t/ha recorded for the same legume when oversown with minimal tillage-drill and zero tillage-broadcast respectively. Proportions of other herbaceous species were very low in ShZtD (11.79 %) and ShMtD (17.51 %) at 8 and 10 MAS respectively. Irrespective of the tillage or sowing methods employed, the two oversown legumes survived competition from existing species and drought of dry season; but with minimal tillage, drilled S. hamata thrived more and contributed higher DM yield amidst other companion species .