Soil Chemical Properties as Affected by Tillage Method, Phosphorus and Lime Application

Continuous land degradation and soil acidity are some of the major causes of below optimal crop yields in Kenya. Sustainable crop production therefore calls for efficient soil health management strategies. Field experiments were carried out at Waruhiu Farmers Training Centre, Kiambu for two seasons to evaluate the effects of tillage methods, phosphorus and lime application on selected properties of acid soils. Ploughing, strip tillage and hand hoe tillage methods and, DAP + lime (DAPL), TSP + lime (LP), TSP (P) were evaluated. Burnt lime at 3.2 tones ha-1 rate was used as lime source while 52kg P ha-1 was used as Phosphorus source. Obtained data indicated that the soils were strongly acidic with high exchangeable Al3+ and Al saturation, low cation Exchange capacity (CEC) and available P. Combination of Ploughing, lime and phosphorus in form of TSP significantly (P ≤ 0.05) led to > 38% increase of soil pH, >75% extractable P, 51% exchangeable Ca, >60% CEC, 54% Exchangeable Mg and reduced Al concentrations by >83% compared to the control. Similarly, combination of ploughing, DAP and lime significantly (P ≤ 0.05) increased CEC by 42% and available P by 81% compared to control. DAPL was observed to significantly (P ≤ 0.05) promote higher levels of exchangeable Al Compared to control and LP in both seasons. Plough DAPL also increased available P by 49% compared to strip DAPL. Strip LP significantly increased Exchangeable Ca by 46% compared to control. Sole tillage methods did not significantly affect soil properties. It can, be concluded that integrating ploughing with either DAPL or LP improves the selected acid soil properties. There is however need for long term studies to understand long term effects of the fertilizer- lime -tillage methods interaction on soil acidity management.