Leaf litter species affects decomposition rate and nutrient release in a cocoa plantation

Abstract

Mineral nutrient fluxes derived from litterfall are key components of nutrient biogeochemical cycles in both natural and agroforesty systems. Cocoa production systems are generally nutrient depleted and may benefit from on external nutrient application to maintain primary productivity. However, in developing countries the main source of nutrients is often nutrient recycling through decomposing leaf litter, and in this regard shade-tree species play an important role in cocoa agroforestry. This study aimed to investigate the nutrient inputs of litter from two shade-tree species (Canarium indium and Gliricidia sepium) and cocoa trees (Theobroma cacao) after 15 months of decomposition in a cocoa plantation. Litter from G. sepium lost more mass (59%) than T. cacao (37%) and C. indium (10%), and showed a higher average concentration of total nitrogen (TN), boron (B), iron (Fe) and phosphorus (P) after 15 months of field incubation than that of C. indium. It also showed a low C:N ratio and N release, which suggest N mineralisation. All litter species showed high C:P ratio and negative P release, which suggests P immobilisation. Litter from G. sepium and T. cacao showed a rapid K release after 1 month of decomposition. The differing mass loss rates and litter nutrient concentrations of the three species could benefit T. cacao by providing asynchronous nutrient inputs and improve long-term sustainability of mixed-species plantations.