Effects of fertilizer types on growth and bulb yield of garlic (Allium sativum L.) varieties in Ogbomoso, Nigeria

Garlic (Allium sativum L.) is an economically and nutritionally valuable crop widely consumed for its culinary and medicinal benefits. However, its productivity in Nigeria remains low, largely due to suboptimal agronomic practices and limited information on appropriate fertilizer types and varietal differences. This study was therefore conducted to evaluate the influence of different fertilizer types and garlic varieties on the growth, and bulb yield of garlic in Ogbomoso. The treatment consisted of two garlic varieties (Sokoto local and Pretty garlic) and six fertilizer treatments: F1 (No fertilizer), F2 (100% NPK 15-15-15), F3 (100% Compost), F4 (50% NPK + 50% Compost), F5 (75% NPK + 25% Compost), and F6 (75% Compost + 25% NPK). The 2 × 6 factorial experiment was arranged in a Completely Randomized Design (CRD), replicated four times. Data were collected on growth, yield and yield parameters. Data collected were subjected to Analysis of variance (ANOVA) and treatment means were separated using Duncan’s Multiple Range Test at a 5% significance level. Results showed that Pretty garlic was significantly higher (p≤0.05) in all growth and yield parameters than Sokoto local variety. Although, Sokoto local variety demonstrated more vigorous early growth, with higher numbers of leaves, tillers, clove count per bulb, and greater bulb firmness. Among the fertilizer treatments, 100% compost significantly enhanced (p≤0.05) vegetative growth, while the combination of 50% NPK + 50% compost resulted in the highest bulb yield (138.67 kg/ha). A significant interaction (p≤0.05) was observed between variety and fertilizer type for all data collected, indicating that the response of garlic to fertilizer application is variety-dependent. In conclusion, pretty garlic variety fertilized with integrated application of 100 kg/ha NPK 15:15:15 + 5 tons/ha Tithonia compost were recommended for optimum production of garlic in the study area.