Estimating the Amount Litterfall and the Rate of Decomposition: The Case of Two Selected Agroforestry Species in the Aba Gerima Watershed, Northwest Ethiopia

Litter decomposition is influenced by litter quality, decomposer activity, macro- and microclimatic conditions, and soil nutrient status, while mixing leaves of species with different resource qualities and structural characteristics can further modify the physical and chemical environment in which decomposition occurs. The selection and use of appropriate agroforestry tree species that maintain soil nutrients thereby improving productivity remains to challenge in low-input agricultural systems. Therefore, this research focuses on two agroforestry tree species, C.macrostachyus and C.africana. This study evaluated the litterfall and decomposition rates of two agroforestry tree species, C. macrostachyus , and C. africana , in the Aba Gerima watershed to improve soil nutrient management in low-input agricultural systems. Using litter-bag techniques and RCBD design, estimating the amount of litterfall was collected every 15 days from February to May 2023, and decomposition rates were monitored over 30, 60, 90, and 120 days during both dry and wet seasons for February to May 2023 and June to September 2023, respectively. Soil samples were analyzed for physicochemical properties of the under-canopy and outside-canopy. Results indicated that C. africana produced more litterfall (5.89 t/ha) compared to C. macrostachyus (5.19 t/ha). However, C. macrostachyus decomposed faster, with higher mass loss (94% in the dry season) and a greater impact on soil nutrient input. Both species showed no significant difference in decomposition during the wet season. The study concludes that litterfall and organic matter from C. macrostachyus and C. africana can be used as mulch or compost to enhance soil fertility. Raising community awareness about conserving these trees in cropland and homegarden agroforestry practices can improve soil fertility and crop productivity.