Soil nutrient contribution and factors affecting the adoption of Albizia Chinensis trees in coffee farming systems: A case study of Mukono District

Abstract

Albizia chinensis was introduced in Uganda as a shade tree for clonal coffee with the aim of improving yields of the coffee beans. But since the introduction of Albizia chinensis as shade trees, the rate of adoption has remained low. This study was conducted to assess the contribution of Albizia chinensis trees towards soil nutrient enhancement and the factors that affect their adoption in farming systems in Mukono District. The objectives were to determine the variations in the distribution of nutrients in the top and sub-soils under Albizia; to determine the levels of nutrients and soil pH under Albizia - coffee farming systems with Albizia trees at different ages; to compare levels of nutrients under Albizia - coffee systems with those in the pure coffee plantations; and to find out the socio-economic factors affecting the adoption of Albizia chinensis integration in coffee farming systems. Four blocks containing Albizia/coffee systems 4-year (B1); 7-year (B2) and 10-year (B3) Albizia trees and pure coffee stand (B4), which acted as a control, were used for soil nutrient data collection. Socio-economic data were collected on the rate of technology adoption by use of structured questionnaires. There was no significant difference in the levels of nitrogen recorded in the soils under 4-year and 7-year Albizia trees although a higher value of the nutrient was noted in the topsoil than in the subsoil under 10-year Albizia trees. Soil pH and the levels of percentage nitrogen and phosphorous increased with the age of Albizia chinensis trees in the farming system. Education level and annual income were the two significant factors hypothesized to influence the intensity of adoption of agroforestry technology. More than 80% of the farmers did not access credit facilities in the last 4 years even though 60% had received extension education in the sub-county. All the respondents had planted Albizia chinensis trees in coffee gardens with the aim of improving soil fertility and productivity. It is recommended that Government through its Development Strategy and Investment Plan (DSIP), should promote the integration of Albizia chinensis trees in coffee gardens in the region. Meanwhile the National Agricultural Advisory Services (NAADS) should consider continuous provision of extension education for Albizia chinensis trees’ adoption.