Selected Soil Chemical Properties and Their Correlations with Maize Growth and Yield Under the Influence of Cropping System, Site and Nitrogen Fertilization.

The type of cropping system that increase the soil chemical properties is very complex and the correlation between soil chemical properties on maize need to be addressed. In this way, the study was conducted to investigate the effect of cropping system, site and nitrogen fertilizer on soil chemical properties and the correlation with maize growth and yield. A factorial experiment randomized in complete block design with two replications was conducted during 2011/12 and 2012/13 planting seasons. The experiment consisted of five management systems, namely, monocropping cowpea, Monocropping maize, rotational maize, rotational cowpea and intercropping maize-cowpea. The amount of 0 and 95; 0 and 92; 0 and 113.5 kg N ha^-1 were applied on maize plots, while the amount of 0 and 20; 0 and 17; 0 and 23.5 kg N ha^-1 were applied on cowpea plots at Potchefstroom, Rustenburg and Taung respectively. The laboratory analysis involved soil N-NO₃, N-NH₄, Bray 1-P and exchangeable K. Soil collected from cowpea plots planted on monocropping and rotational systems had significantly (P < 0.05) higher soil N-NO₃ than soil collected at other cropping systems. Soil collected at maize plot planted on monocropping and intercropping systems had significantly (P < 0.05) higher Bray 1-P than soil collected on other cropping systems. Site had significant (P < 0.05) effect on Bray 1-P, N-NO₃ and exchangeable K. Soil collected at Potchefstroom and Rustenburg had significantly (P < 0.05) higher exchangeable K than soil collected at other sites. Soil collected at Potchefstroom and Taung had significantly (P < 0.05) higher Bray 1-P and N-NO₃ than soil collected at Rustenburg. There were positive correlations between soil N-NO₃, N-NH₄ and exchangeable K on maize growth and yield. In this study, it was revealed that cropping system and site play a pivotal role on soil chemical properties.

Keywords: N-NO3, N-NH4, Bray 1-P, Exchangeable K.