Soil Nutrient Budget Analysis for Intensive Vegetable Production Systems in the Kano Fadama, North West Nigeria

This study conducts a professional soil nutrient budget analysis for intensive dry-season vegetable production systems in the Kano fadama irrigation areas, Kano State, located in Nigeria's North West geopolitical zone. The Kano fadama supports one of Nigeria's largest concentrations of irrigated vegetable production, but the sustainability of current nutrient management practices has not been systematically evaluated against a nutrient balance framework. Using a professional nutrient budget methodology, 30 representative fadama vegetable farms were selected in Kumbotso, Dawakin Tofa, and Ungogo local government areas. Over one complete dry season, all nutrient inputs (synthetic fertilisers, manures, irrigation water, and atmospheric deposition) and all nutrient outputs (crop harvest, leaching, and gaseous losses) were quantified. Soil sampling at the beginning and end of the season provided data on in-season nutrient stock changes. Nitrogen, phosphorus, and potassium balances were calculated for each farm and compared across farm types. Findings revealed strongly positive phosphorus balances averaging plus 62 kg P per hectare per season, indicating phosphorus accumulation and risk of runoff enrichment in the drainage channels. Nitrogen balances ranged from negative on poorly fertilised farms to highly positive on intensively manured plots, suggesting both depletion and over-application risks within the system. Potassium was almost universally deficient. The study recommends crop-specific nutrient management plans, reduction of phosphorus application on already-enriched soils, and introduction of potassium supplementation as the three priority nutrient management reforms for the Kano fadama vegetable system. Keywords: nutrient budget, vegetable production, Kano fadama, phosphorus accumulation, potassium deficiency.