Soil Properties and Fertility Management within Ruiru Peri-Urban Area in Kiambu County, Kenya

Peri-urban agriculture is a common practice around many towns and cities in Africa because of the ready urban market for farm commodities. However, it is constrained by a myriad of factors like lack of land tenure and poor soil fertility management strategies. This study focussed on soil physicochemical properties and fertility management in Ruiru Sub County, which is a peri-urban area, in Kiambu County of Kenya. Data was obtained from soil samples that were collected from ten small contact farms identified by the Sub-County Ministry of Agriculture and analysed for selected physicochemical parameters critical in soil fertility management. The results from this study indicated that most farmers were tenants growing leafy vegetables on small farms ~0.1 ha. Soil fertility was mainly maintained using organic manures, while tillage was done by hand. Both practices signal the limitations imposed by the small farm size and lack of land ownership. The soil pH was 6.3 ±0.87, which was ideal for protontransfer reactions in the soil and availability of nutrients for plant uptake. Soil fertility was mostly limited by the interaction of soil pH, K and Ca (30%), total N, OC and Zn (27%) and Cu (15%), Mg (10%) and P (9%). Therefore, the management of Ca fertilisation in this area is key because it is the Ca concentration of the soil solution that influences K and pH through ion exchange and K release. Key words: Organic manures, Inorganic fertilizers, Crop farming, Principle component analysi