Integrated soil fertility management using cocoa bean shells improves soil chemical properties, coconut yield and mitigates environmental pollution

Abstract

One approach to sustain and intensify coconut production is nutrient cycling through an integrated soil fertility management strategy. This strategy may include transferring crop by-products from one farm commodity to another. One such promising by-products identified is cocoa bean shells (CBS), which is in abundance and could serve as an environmental pollutant at Bamiankor, which is a forest zone and an important area for coconut and cocoa productions, located in the Western region of Ghana. Following this, a 42-month integrated soil fertility management field study was conducted to assess improvements in selected soil chemical properties, coupled with vegetative, and reproductive parameters in a Sri Lankan Green Dwarf (SGD) coconut genotype under various fertilizer treatments. The treatments included: no-fertilizer control (CK), nitrogen-phosphorus-potassium (NPK) fertilizer, cocoa bean shells (CBS), and NPK+CBS, which were arranged in a randomized complete block design (RBCD) in three replications. There were appreciable increases in values of soil pH, total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), and available phosphorus (AP). Values in carbon to nitrogen (C:N) ratio after treatment with CBS, however, were significantly reduced. It was observed that collar girth from palms treated with NPK+CBS were significantly higher compared to other treatments. Similarly, number of leaves, percentage of palm inflorescence, and number of nut-load palm−1 year−1 were all significantly higher under NPK+CBS treated palms compared to the other treatments. In conclusion, CBS in combination with NPK fertilizer is recommended as a good strategy to intensify coconut production. However, for a long-term benefit, circularity, cleaner, and sustainable production, addition of sole CBS is advocated. Adoption of this management strategy will also potentially mitigate the negative environmental consequences associated with accumulation of CBS in studied area.