Litter diversity improves litter fall and nutrients sustainability in an agroforestry system in a semi-arid ecosystem in Juja, Kenya

Abstract

Trees in agroforestry are important for the cycling and sustainability of nutrients; however, documentation on the decomposition and nutrient release as influenced by tree diversity is scarce in agroforestry. This study aimed to determine the effect of litter diversity of five commonly used agroforestry tree species (Cordia Africana (Lam.), Faidherbia albida (Del.), Grevillea robusta (A.Cunn.), Acacia seyal (Del.), and Acacia xanthophloea (Benth.) on nutrient release in an agroforestry ecosystem in Juja, Kenya. Litter bag techniques were adopted to determine the quantity and quality of nutrients released in the mixed litters of the five tree species compared with the individual species. The mineralization of N, P, K, and C significantly increased in A. seyal among individual tree litters, hence, proves its suitability for agroforestry. However, tree diversity increased litter fall by 82% and 33% compared with those of F. albida and A. xanthophloea, respectively. Potassium and C released in the mixed litter were not significantly different from their corresponding monocultures. Meanwhile, an antagonistic non-additive effect of mixed litter was observed on N and P after 90 days of decomposition, thereby ensuring their retention and sustenance in agroforestry system.