Tropentag, September 16 - 18, 2026, Göttingen "Towards multi-functional agro-ecosystems promoting climate-resilient futures"

Enduring gains in maize yield and soil hydraulic function from cocoa pod husk compost in Ghana

University of Ghana, Forest and Horticultural Crops Research Centre, Ghana

Abstract

Low soil fertility and poor soil hydro-physical properties limit crop productivity in tropical smallholder systems, with these constraints worsening under increasing climate variability. Ghana produces approximately 600,000 tonnes of cocoa beans annually, generating about 6,000,000 tonnes of cocoa pod husk (CPH) as a by-product. This abundant biomass represents a significant opportunity for nature-based soil amendment to enhance soil functions and support climate-resilient crop production systems. However, in most smallholder farming systems in Ghana, organic amendments are commonly surface applied without incorporation, leading to nutrient losses through runoff and volatilisation. Subsurface placement has been proposed to improve nutrient retention, but its effectiveness under tropical field conditions remains insufficiently understood. This study evaluated the effects of compost placement depth on maize yield and soil hydraulic conductivity over three growing seasons in Ghana. CPH compost was applied at 20 t/ha and incorporated either into the topsoil (0–15 cm) or into a subsurface layer (15–30 cm), alongside an unamended control. Compost application significantly increased maize yield across all three seasons, regardless of placement depth. Seasonal grain yield increases ranged from 30–120% under surface application and 45–100% under subsurface application relative to the control. Over the three seasons, compost application produced an additional 14 t/ha of total dry matter yield and 5 t/ha of grain yield compared to the control. Temporal trends showed stronger early-season responses under surface application during the first two seasons, while subsurface placement produced more sustained benefits and outperformed surface application in the third season. Compost also significantly improved soil hydraulic conductivity. Surface incorporation increased hydraulic conductivity by approximately 280% relative to the control, while subsurface application increased it by about 85%. Surface application resulted in about 100% higher conductivity compared to subsurface placement. These findings demonstrate that both compost use and placement depth critically influence crop yield and soil water dynamics. Optimising the use of locally available CPH compost can improve crop yield, soil hydraulic function, and support sustainable intensification and climate resilience in tropical smallholder agro-ecosystems.

Keywords: Soil fertility

Contact Address: Eric Oppong Danso, University of Ghana, Forest and Horticultural Crops Research Centre, H183 granite city st ed-1284-7607, 233 Accra, Ghana, e-mail: eodansoug.edu.gh