Fertilizer Recommendation for Maize and Cassava Within the Breadbasket Zone of Ghana

Abstract

This study was to review and update fertilizer recommendation for maize and cassava to improve yields and incomes of food crop producers as well as sustain the environment. The trials covered part of the semi-deciduous forest, forest savanna transition and the Guinea savanna agro-ecological zones which form the breadbasket area of Ghana. Five on-station and 200 on-farm fertilizer trials were conducted on maize and cassava. Random complete block design in four replications was used on station. The on-station research treatments were 15, with various combinations of N, P₂O₅ and K₂O and the on-farm trails had 5 N rates; 0, 45, 90, 135, and 160 kg N ha⁻¹ with 60 kg ha⁻¹ P₂O₅ and 70 kg ha⁻¹ K₂O as basal application except on the zero fertilizer plots. Maximum yields obtained across the three ecological zones ranged from about 2000 to 9000 kg ha⁻¹. Yields followed quadratic trends in most locations and years, with a clear optimum application rate of 90 kg N ha⁻¹. In some districts, yields continued to increase steadily up to 135 kg N ha⁻¹, after which yields could not increase with additional N application. In some situations the economic optimum rate was lower than the biological optimum rate. Cassava root yields followed a distinct quadratic trends across the Forest savanna transition agro-ecological zone with yields increasing with application of N up to 60 kg N per hectare. Optimum N rate for cassava production was 60 kg N ha⁻¹. The full treatment is therefore 60–45-90 kg ha⁻¹ N-P₂O₅-K₂O which gave an average yield of about 50 T ha⁻¹.