Soil water relations of a Nigerian typic haplustult amended with fresh and burnt rice-mill wastes

Abstract

The soils in the Abakaliki agro-ecological region of southeastern Nigeria are plagued with characteristics that impede optimal soil water conditions. Four rates (12.5, 25.0, 37.5 and 50.0 Mg ha −1) of fresh (FW) and burnt (BW) rice-mill wastes were incorporated in a typic haplustult planted with maize ( Zea mays L.) to improve the immediate and long-term water conditions of the soil. Results showed that significant changes in bulk density and total porosity occurred at the application rates of 25.0 and 50.0 Mg ha −1 in the FW and BW amendments, respectively. At an application rate of 50.0 Mg ha −1, the permanent wilting point water content (18.0%) in the FW amendment was significantly higher than the BW amendment. Similarly, the FW amendment at the same application rate resulted in the infiltration rates (i) of 2250 and 2181 mm h −1 in the first and second seasons, respectively. These figures are significant improvements relative to the BW amendments and the control. Percent organic carbon (OC), dry aggregate size >0.5 mm and water stable aggregates (WSA) > 0.5 mm accounted for 43% and 77%, respectively of the improved infiltration. Sorptivity and A parameter of Philip's equation increased significantly with increasing rate of the FW amendment. Appropriate moisture conservation techniques are required to accelerate the rate of decomposition of the FW amendment in order to enhance its contribution to soil water retention.