Evaluation of Soil Physicochemical Properties under the Canopy of Coffee Shade Trees Effect (Cordia africana and Erythrina abyssinica) in Arsi Golelcha District, Ethiopia

Abstract

Agroforestry from which soils are derived effectively sets the upper limit of nutrient supply. Contrasting this vegetation component of the ecosystem acts as a means by which mineral nutrients are sequestered, and carbon and/or nitrogen is fixed, and subsequently added to the soil through litter fall by decomposers of organic matter. Coffee shade trees is important to improve over all soil and coffee  health, sustain and restore agroecology,biodiversity, and diversified nature based agroforestry practices. The study was conducted on farmers’ fields in Golelcha District of East Arsi Zone, Ethiopia. The study was intended to evaluate the influence of coffee shade trees on selected soil physicochemical properties under the canopy of  (Cordia africana and Erythrina abyssinica ) trees and to get appropriate distance of coffee seedling plantation area in which away from shade tree trunks. Randomized complete block design on three farmers’ fields as a replication in each PAs were used for data collection. A total of 48 circular samples were taken for both treatments’ parameters, under both coffee shade tree species at the distance of 1m, 3m, 6 m and 25m away from shade tree trunk including unshaded zone. The two widely grown indigenous coffee shade tree species in the area were Cordia africana and Erythrina abyssinica. Even though farmers’ preference focused on Cordia africana tree based on its utility, the best results were recorded under Erythrina abyssinica tree. The outcome had a significant value at (p<0.05) and highly significance value at (p<0.01) between and within the treatments. Integration of shade in coffee farming system created creditable promising in producing organic coffee as a result of organic soil improvement. Shade utility was also adopted as ecologically sustainable, economically viable and socially acceptable practice. The second distance layer (3m) away from shade tree trunks illustrated the highest mean value across PAs in most parameters. Almost all the given soil parameters’ value increased significantly under the tree canopy than in the open area in both PAs showing decreasing trend with increasing distance from the tree trunks except phosphorus. Average result of both PAs' soil; the greater value of pH 44%, and 54%, OC; 60.5% and 92%, TN; 40% and 50.5%, CEC; 68.75% and 87%, ex. K; 13.5% and 14%, silt; 22.65% and 27.5% than open area were detected under the canopies of Cordia africana and Erythrina abyssinica, respectively. The best shade tree was Erythrina abyssinica and the recommended distance of coffee seedling plantation area away from shade tree trunk was 3m. Generally, the imperative indicator of the treatment’s means difference were indicated between shaded and unshaded rather than within shaded means variation at most treatments’ parameters.

Keywords: Coffee-based agroforestry system, Coffee shade value, Soil fertility ascription and Coffee quality attributions.