Beyond adoption: the interaction between organic and inorganic fertilizer application, and vegetable productivity in Ghana

This study explores the causal association between organic and inorganic fertilizer application and vegetable productivity in Ghana. Primary data were obtained from 300 pepper, cabbage and lettuce producers. To correct for self-selection bias and endogeneity, Heckman selection and three-stage least-squares models were estimated. More producers used inorganic fertilizers for pepper, cabbage and lettuce production than those who used organic fertilizers. Vegetable producers applied higher quantities of organic fertilizers (2830 kg) per acre than inorganic fertilizers (880 kg). Organic cabbage and lettuce producers recorded higher productivity than inorganic producers, but inorganic pepper producers had higher productivity than organic producers. However, vegetable producers who applied either organic or inorganic fertilizers, or both, recorded higher productivity than those who did not apply fertilizer. Factors that enhance the application of organic and inorganic fertilizers and vegetable productivity are education, farm size and production for export, land ownership, farmer association membership and perception about fertilizer price. Organic and inorganic fertilizer application improves vegetable productivity, and productivity promotes fertilizer application. Private agencies and government should subsidize fertilizers, improve producers' access to agricultural information, and train producers on productivity-enhancing agronomic practices.