Zero tillage improves soil properties, reduces nitrogen loss and increases productivity in a rice farmland in Ghana

Abstract

Soil fertility in Ghana continues to decline due to the overdependency on farm machinery to till the land coupled with the continuous application of mineral fertilizer, which has a resultant effect on agricultural non-point source (AgNPS) pollution. A two-year field experiment was conducted to evaluate the effects of different tillage methods on soil properties, nitrogen loss reduction and rice productivity of a gleysol, developed over granite. Five tillage methods-namely, zero tillage direct seeding (ZTDS), zero tillage transplanting (ZTTS), reduced tillage direct seeding (RTDS), reduced tillage transplanting (RTTS), and conventional tillage (CT)-were studied in a Randomized Complete Block Design (RCBD) with three replicates. After two cropping seasons, soil bulk density was in the order of (ZTTS = ZTDS) > RTDS > RTTS > CT. ZTDS and ZTTS were associated with significantly higher levels of nutrients in the top soil (0-20 cm) as compared with the rest of the treatments. Plant height was in the order of CT > RTTS = ZTTS > RTDS > ZTDS. The highest grain yield was recorded by both CT and ZTTS significantly different from the rest of the treatments. ZTDS recorded the highest stover yield for both years. Subsequently, CT was associated with high release of potential pollutant loads which could lead to AgNPS pollution, as is evident from the high nutrient loss. Considering the high nutrient concentration at 0-20 cm, the reduced nutrient movement and the corresponding yield improvement, ZTDS and ZTTS are recommended for farmers in Ghana to ensure sustainable rice production, reduce AgNPS pollutant movement and ultimately provide an eco-protective and friendly environment for sustainable rice production.