Impact of rice straw biochar and irrigation on maize yield, intercepted radiation and water productivity in a tropical sandy clay loam

Abstract

Continuous cultivation of staple crops to feed a growing population in the semi-deciduous agro-ecological zone of eastern Ghana (SDAG) has led to degraded soils and decreased crop yields. Biochar constitutes a potential remedy as it is often reported to improve soil health and increase crop yield of infertile soils. We thus conducted an experiment over two seasons to evaluate the impact of rice straw biochar on yield, radiation interception and water productivity of maize grown in the SDAG. The biochar was incorporated into the soil at rates of 0, 15 and 30 t ha−1 under irrigated and non-irrigated conditions. Maize grain yield (GY), accumulated intercepted photosynthetic active radiation (IPAR) and water productivity (WP) were compared among treatments. Regardless of season, the highest GY, IPAR and WP were achieved in plots amended with 30 t ha−1 biochar. A biochar rate of 30 t ha−1 increased grain yield by 17% and 36% and IPAR by 19% and 25% in 2017 and 2018 seasons, respectively, compared to a no biochar control. For both seasons, maize GY for the 15 t ha−1 treatment was statistically similar to that of 0 t ha−1 treatment whether irrigated or not. Irrigation increased grain yield by 9% and IPAR by 3% in 2017 and with 30% and 17%, respectively, in the dryer 2018 season. The effects of biochar and irrigation were additive. Water productivity from the 30 t ha−1 treatment was significantly higher in the non-irrigated than in the irrigated plots. Overall, in the SDAG, a biochar soil amendment rate of 30 t ha−1 might be a viable solution for farmers to increase yield and enhance water productivity of maize. Future studies should focus on the effect of biochar on the soil and crops over a longer time span in order to recommend viable management options to the farmers in SDAG.