SOIL ORGANIC CARBON AND pH VARIABILITY ACROSS COCOA-PRODUCING AGROECOLOGICAL ZONES: IMPLICATIONS FOR SITE-SPECIFIC SOIL FERTILITY MANAGEMENT

Abstract

The soil organic carbon (SOC) and soil pH are both important characteristics of soil fertility and play important roles in soil nutrient availability, biological activity, and long-term cocoa production. The study quantified the SOC and pH variation for the different cocoa-producing agroecological zones of Ghana and determined the implications for site-specific fertility management. Seven hundred and thirty-nine observations from cocoa-farm soils across the six agroecological zones were used for the analysis of a secondary dataset through descriptive statistics, variability measures, correlation analysis, multivariable regression, and spatial assessment. Mean SOC was 0.393 ± 0.235, while mean soil pH was 5.345 ± 0.744. The highest mean for SOC and pH was recorded for MSNW, while the lowest was recorded for DSIZ for SOC and WE for pH. The relative variability of SOC was significantly larger than that of pH. There was a weak, but significant, positive correlation between SOC and pH. SOC was related to agroecological zone, pH and clay content and among the parameters of pH variation were associated with agroecological zone, clay content, exchangeable iron and aluminium. The results indicate that there are different fertility limitations in the cocoa soils depending on the zones. Incorporating SOC and pH can in turn, help to manage for targeted restoration of organic matter, acidity correction and better management of site-specific soil fertility for sustainable cocoa production, in a heterogeneous cocoa-growing landscape in the face of changing environmental conditions.