Abstract

This study explored the benefits of Faidherbia albida on soil fertility in farmers’ fields in areas which were suitable for Conservation Agriculture (CA) and where mature stands of F. albida already existed. It investigated the effects of F. albida on soils by testing for differences in the soil reaction (pH), total nitrogen, potassium, phosphorus and organic carbon at increasing radial distance from the tree trunk. Soil samples were collected from under and outside the canopies of 102 F. albida trees in four districts situated in the Southern and Eastern provinces of Zambia. The results showed evidence of a negative linear relationship between distance from F. albida and total nitrogen (p = 0.003), organic carbon (p = 0.0001), and potassium levels (p = 0.0001) but not for available phosphorus (p = 0.708) and soil reaction pH (p = 0.88). The nutrient levels were 42, 25 and 31% higher under the tree canopies than away for total nitrogen, potassium, and organic carbon respectively.F. albida added significant amounts of the agriculturally important nutrients which resource constrained households had difficulties replenishing to the soils through mineral fertilizer amendments because of their limited ability to purchase mineral fertilizers. It was concluded that F. albida improved soil fertility in farmers’ fields and could be promoted in smallholder CA systems in Zambia.

Key words: Faidherbia albida, soil fertility, conservation agriculture, biological nitrogen fixation, Zambia.