Effects of soil amendments and weeding regimes on growth and yield potential of rice (Oryza sativa L.) under different water sources in the Guinea Savanna

Enhancing soil fertility and reducing the devastative effect of weed competition in rice is increasingly important and critical for ensuring a sustainable increase in rice production and secure food supply. Field experiment was conducted at Bontanga in the Northern Region of Ghana to investigate the effect of soil amendments and weeding regimes on growth and yield of rice under different moisture sources. The experiment was a three-factor experiment laid in a split plot design with three replications. The factors were water source (irrigation and rainfed), four levels of soil amendments [no fertilizer (NF), poultry fertilizer (PF), mineral fertilizer (MF), cow dung (CD)] at the same N rate (60kg N ha-1) and four levels of weeding regime (weedy check (W1), weed free (W2), one hand weeding + twice herbicides application (W3) and twice hand weeding + one time herbicides spray (W4). Parameters measured were tiller count, weed biomass, weed control efficiency, grain yield and cost analysis. Results showed that water source, soil amendments and weeding regimes had influenced rice yield. Irrigation increased rice grain yield by 49% compared to rainfed. Application of CD, MF and PL at the same N quantity increased grain yield by 5.4, 28 and 8%, respectively compared to NF. Among weeding regime, weed free reduced weed density and biomass, this translated to greater tiller counts and increased grain yield. Weed interference in weedy check reduced grain yield by 48, 30 and 26% compared to W2, W3 and W4, respectively. Irrigation increased cost of production by 7%, however, cost:benefit ratio increased by 44% compared to rain fed conditions.