VERIFICATION OF INTEGRATED SOIL FERTILITY MANAGEMENT AND WEED INTERFERENCE ON NERICA RICE IN THE GUINEA SAVANNA UPLANDS

Abstract

Improving soil amendment and reducing weed-crop competition in rice cultivation could increase production of the crop under upland conditions. A field study was conducted to verify integrated soil fertility management and weed interference on NERICA 1 in the Guinea savannah uplands of Ghana to determine their interactive effects and examine the synergy between organic and inorganic soil amendments on yield components and grain yield. Four levels of soil amendment and six weeding regimes laid in Randomized Complete Block Design with four replications were studied. Results indicated full rate of NPK (60-60-30 kg/ha) combined with hand weeding at 3 and 6WAP maximized most growth and yield parameters of NERICA 1 with grain yield of 3000kg/ha. The same treatments minimized weed index (WI) followed by weeding once at 3WAP when combined with either full dose of NPK or organic manure. The best timing for one hand weeding as practiced by some farmers was 3WAP to obtain appreciable yield in rice. Tillering at 50 DAP and productive tillering were maximised by both full rate of NPK and half doses of NPK and organic manure applications with 250 tillers/m2 respectively 200 productive tillers/m2. The synergy between inorganic and organic manure at half doses was exemplified and could be exploited by farmers for increased crop performance. Full rate of NPK maximised LAI and straw biomass followed by half doses of manure and NPK fertilizer. Notably twice weeding at 3 and 6 WAP recorded the highest LAI, tillering and productive tillers, and reduced straw biomass only by 20% relative to the weed-free control. 1000 seed weight of NERICA 1 was reduced only by weedy control below 25g, even in the presence of soil amendments. Weed flora was dominated by annuals and consisted of 55% broadleaves, 25% grasses, 12% shrubs and 6% sedges.