Development of Site-Specific Lime Recommendations for Cocoa-Based Farming Systems in Ondo State, South West Nigeria

This study develops site-specific lime recommendation protocols for cocoa-based farming systems in Ondo State, located in Nigeria's South West geopolitical zone. Cocoa is the dominant cash crop of Ondo State, and soil acidity is a widespread constraint on cocoa garden productivity and tree health. Despite the well-established relationship between soil pH, aluminium toxicity, and cocoa performance, no systematic lime recommendation framework exists for Ondo State's cocoa-producing areas. Using a professional advisory approach, 60 cocoa farms were characterised by soil sampling in Owo, Idanre, and Ile-Oluji local government areas. Soil pH, buffer pH, exchangeable aluminium, cation exchange capacity, and organic matter were measured. The Shoemaker-McLean-Pratt (SMP) buffer method was used to calculate lime requirement for target pH values of 5.8 and 6.2 for each farm soil. Lime response trials were established on eight farms with three lime rates and monitored for two seasons for soil pH response, exchangeable aluminium reduction, and cocoa foliar nutrient status. Findings revealed that 83 percent of surveyed cocoa farms had pH below 5.2 and 72 percent had exchangeable aluminium exceeding 2.0 cmolc/kg. The SMP buffer lime requirement averaged 1.8 tonnes per hectare for target pH 6.0. Lime response trials confirmed significant pH correction and improved cocoa leaf nitrogen and calcium status. The study delivers a practical lime recommendation manual for Ondo State cocoa extension officers, with application rate tables stratified by soil buffer pH and organic matter class. Keywords: lime recommendation, cocoa, soil acidity, Ondo State, aluminium toxicity.