Assessment of soil fertility and quality for improved cocoa production in six cocoa growing regions in Ghana

Abstract

Inadequate or lack of prudent soil fertility management by cocoa farmers leads to nutrient depletion in cocoa production fields. The objective of this study was to assess current soil fertility status of cocoa farms from six cocoa growing regions in Ghana and to derive an integrated soil quality index (SQI). Composite soil samples from 0 to 30 cm depth were collected from 100 selected farms covering the six cocoa regions. Soil pH, %C, %N, total and available P, cation exchange capacity (CEC), and exchangeable cations (Ca, Mg, K) were measured. These parameters were analyzed using principal component analysis, normalized, and integrated into a weighted-additive SQI. Soil pH of majority (59.0%) of the farms was within 5.6–7.2, suitable for cocoa production. Available soil-P in most (82%) of the farms was < 20 mg kg−1. Soil quality in most farms was generally low, with an average SQI of 0.41 ± 0.14. Soil quality in Western region farms was relatively high, followed by farms in Brong Ahafo and Volta regions. Farms in Eastern, Central and Ashanti regions had the least soil quality. Soil pH, CEC and available P showed great influence on SQI. Given the latter observation, diagnostic yield response experiments should be conducted, which include: application of locally generated liming materials, organic residues and agro-mineral base fertilizers such as phosphate rock and dolomite.