Abstract

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.

Key words: Available P, dolichos, lime, NPK fertilizer, pH, total N.