Decomposition and nutrient release from the mixed leaf litter of three agroforestry species in the Sudanian zone of West Africa

This study was carried out to determine the rates of decomposition and nutrient release from pure and mixed leaf litter samples of three agroforestry species (Azolla africana Desv., Detarium microcarpum Guill. and Perr. and Vitellaria paradoxa C.F.Gaertn.) that have potential use as green manure. Litterbags containing a total of 5 g of pure and mixed leaf litter of different quality levels were incubated under field conditions from July to November in 2017. Litter decomposition and nutrient release (N, P, and K) rates were assessed in each litterbag. The decomposition rate (k) indicated that pure A. africana litter decomposed faster (k = 0.406 week−1) than its mixture with V. paradoxa (k = 0.114 week−1) and D. microcarpum (k = 0.103 week−1). The slowest decomposition rates were found for the pure D. microcarpum (k = 0.075 week−1) and V. paradoxa (k = 0.071 week−1) leaf litters. Mixing with A. africana litter increased the decomposition rate of both D. microcarpum and V. paradoxa leaf litter. We conclude that mixing litter of different quality can accelerate the decomposition of pure litter with poor quality and represents a practical biomass management option for farmers to improve nutrient cycling in agroforestry systems.