Effect of tea cropping on the structure of some Kenyan soils

Abstract

Experiments were conducted on humic Andosols to investigate the effect of tea cropping on the structural aspects of the soil. Selected fields had the following: moribund tea, tea planted in 1959, tea planted in 1979 and a new forest clearing intended for tea growing. All are situated in Kagaa, Kiambu District, Kenya, within the Tea and Dairy Agro-ecological zone. Disturbed and undisturbed soil samples were taken from 0 to 15 and 15 to 30cm depths. In spite of tea cropping, organic C remained high ( 30 g kg-I) in all the soils and the bulk densities were not significantly different. The moisture content, aggregate stability and saturated hydraulic conductivity of the soils were significantly (P 0,01) improved with cropping. Water retention, structural and hydrological characteristics, including profile water holding and available storage capacities, were not adversely affected by cropping. This suggested that the stagnation or decline in yields is due to other factors.