Effects of lime, NPK fertilizer and intercropping on selected properties of an acid mollic andosol in potato (solanum tuberosum) production systems

This study investigated the effects of intercropping, liming, and NPK fertilizer application on soil pH, available soil phosphorus (P), and total soil nitrogen (N) in potato production system during a two season’s field experiment in Molo sub-county, Kenya. A randomized complete block design with a split-split plot arrangement of treatments and three replicates was used. Main plot factors were NPK fertilizer levels (0 and 0.2 t ha-1). Lime rates (0 and 2 t ha-1) formed the sub-plots and cropping system (sole potato and Potato-Dolichos intercrop) the sub-sub plots. Application of lime increased the soil pH by 0.34 over the control. Sole NPK fertilizer application reduced the soil pH by 2% when compared to the control. Combined application of NPK fertilizer with lime increased soil available P by 6.5, 8 and 6 mg kg-1, and 20.41, 3.91 and 3.58 mg kg-1 in the first and second season over the control, sole lime and sole fertilizer application, respectively. Application of NPK fertilizer under the Potato-Dolichos intercrop increased the total soil N by 0.08% over the control. The study concluded that intercropping, application of lime and NPK fertilizer to mollic Andosols of Molo Kenya is important in increasing soil pH, available P and total N.