Jp Mbuvi

Effects of soil management practices and tillage systems on surface soil water conservation and crust formation on a sandy loam in semi-arid Kenya

Abstract The effect of different soil management practices on crust strength and thickness, soil water conservation and crop performance was investigated on a ferric lixisol in a semi-arid environment of eastern Kenya. The study proved that manure and mulching with minimum tillage have a greater effect on the water balance of crusted soils and maize emergence. There was increase in steady infiltration rates, amount of soil water stored in the soil and better drainage. The physical effect of mulch was less important in the rehabilitation of crusted soils in the study site when it was incorporated into the soil. Manure and surface mulch with minimum tillage should therefore be taken into account in land management and water conservation in the semi-arid areas of Kenya. The response of crops to the improved water availability due to manure with minimum and with conventional tillage and surface mulch was very clear. These management practices should be recommended when considering the effectiveness of soil and water management techniques in the study area.

Field Assessment of the Effect of Cumulative Soil Loss on Soil Productivity

Soil erosion affects physical and chemical soil properties by reducing water infiltration rates, soil water holding capacity, soil fertility and leading to deterioration of soil structure. Research on the relationship between erosion and soil physical and chemical properties has been conducted (Battison et al., 1987; Becher et al., 1985; Frye et al., 1982) but few such studies have been carried out in the tropics (Mbagwu et al., 1984; Yost et al., 1985; Lal, 1985; Belay, 1992; Casanova et al., 1987; Merete, 1992). Results mostly indicate that erosion causes considerable deterioration of soil fertility and reduces rooting depth, causes soil crusting, compaction, loss of soil water storage capacity, diminishes workability and decreases infiltration rates. Crosson, (1985) argued that consequences of eroded soil carried off the farm are not always negative. Some eroded fertile soil may be deposited on less fertile soil, thus enhancing the productivity of the latter. However, the general consensus is that the effect of deposited soil is negative in Kenya (Otieno, 1993; Schneider, 1993).