Impact of some savanna trees on soil quality on smallholder farms in a part of Kano, Nigeria

Abstract

Soil nutrient decline has become a major issue of concern to researchers in the semi-arid region of Nigeria. This condition is further exacerbated by worsening climate and declining environmental quality, amplified by huge population pressure on limited resources. This research investigates the impact of some key savanna tree species on soil quality on smallholder farms in a part of Kano, Nigeria. The results indicate that many indigenous tree species are deliberately left on these smallholder farms in a practice that may be referred to as agroforestry. Inventory of these trees indicates that Vitellaria paradoxa at 25%, Parkia biglobosa at 20%, and Anogeissus leiocarpus at 12%, and Faidherbia albida at 8% are the dominant tree species on smallholder farms in the study area. Laboratory analysis of soil quality at different distances - 2m, 6m and beyond 6m – around the inventoried trees on smallholder farms in the area indicated statistically significant differences in available soil minerals, at 0.02. Eighty-three percent of the farmers corroborated that crops close to trees perform better, in a social survey conducted on some 400 smallholder farmers in the study area. The study recommends: (1) deliberate promotion and regeneration of tree species, most especially leguminous, on smallholder farms; (2) more researches to determine and establish the specific distance(s) at which soil mineral elements are profoundly influenced by trees, and quantifying the actual soil mineral elements that may be made available by each of the different tree species.

Keywords: Agroforestry; Indigenous; Savanna; Smallholder