Economic Effects of Using Improved Maize Varieties, Inorganic Fertilizer and Goat Manure in Smallholder Farms: Evidence from Field Evaluations in Southern Ghana

Maize is a key cereal which contributes to food security with an ever-growing demand in Africa. Therefore, production must be continuously increased to meet demand. One way to achieve increased production is to use improved varieties and soil amendments to enhance productivity. However, the usage of these inputs is low in sub-Saharan Africa including Ghana. To contribute to the literature on the economics of applying soil amendments, especially from season to season, on-farm trials were undertaken in the coastal savannah and semi-deciduous forest zones of Ghana to demonstrate profitability of adopting improved maize varieties and soil amendments. Partial budgeting techniques were employed to compute net benefits and marginal rates of return resulting from a shift in strategy from farmer practice to the use of improved maize varieties and soil amendments. Significantly higher yields were obtained with the improved technologies. Maize plants on the sole inorganic fertilizer had significantly (P < 0.05) higher grain yields for all varieties in the two agro-ecological zones in the major season. In the minor season however, grain yields of maize on the combined treatment of inorganic fertilizer + goat manure was significantly (P< 0.05) higher than the rest of the soil amendments for all varieties in both agro-ecological zone. The fertilizer + manure combination yielded the highest net income in both the major and minor seasons. The marginal rates of return for the shift from farmer practice to soil amendments were highest for the fertilizer + manure combination, irrespective of the maize variety and agro-ecological zone. However, the marginal rates of return were minimal for the local maize variety (landrace). In the minor rainy season, net benefit was greater with soil amendment application than with reliance on residual nutrients from the previous season. Thus, residual soil amendment effects alone cannot sustain maize yields and profitability- soil amendments need to be applied continuously.