On-Farm Experimentation with Improved Maize Seed and Soil Amendments in Southern Ghana: Productivity Effects in Small Holder Farms

Abstract

Maize production in Ghana is limited by several factors including inadequate use of improved varieties and poor soil fertility management. To contribute to addressing these challenges in maize production, two on-farm experiments were conducted each in the semi deciduous forest and coastal savannah agroecological zones (AEZs) of Ghana during the major and minor cropping seasons of 2017. The study adopted a 3 × 4 factorial arranged in an RCBD with four replications in the major season. The factors were three maize varieties (Omankwa, Obatanpa, and Ahomatea) and four soil amendments (goat manure at 5 t·ha−1; inorganic fertilizer (N-P2O5-K2O at 95-37.5–37.5 kg·ha−1); 50% goat manure (2.5 t·ha−1) + 50% inorganic fertilizer (N-P2O5-K2O at 47.5–18.75–18.75 kg·ha−1); and the control (no soil amendment)).To evaluate the residual implications of these soil amendments in the minor season, each plot used in the major season was further divided into two except for the control plot, resulting in a split plot design with factorial of 3 maize varieties × 7 soil amendments. The results revealed a significant interaction between maize variety and soil amendment in both seasons with the use of sole inorganic fertilizer resulting in significantly higher ( $p<0.05$ ) grain yields for all varieties in both AEZs in the major cropping season. In the minor season, the combined treatment of 50% goat manure + 50% inorganic fertilizer resulted in higher grain yields for all the varieties in both AEZs with improved maize (Omankwa and Obatanpa) having significantly higher ( $p<0.05$ ) grain yields (33–40%) than the landrace (Ahomatea). The significantly lower ( $p<0.05$ ) performance of maize varieties on the residual plots in both AEZs suggests that there were minimal residual effects from the major season. Thus, in continuously cropped fields, the use of inorganic fertilizer + goat manure is required in addition to improved seeds for sustainable maize production.