Infiltration and Sorptivity Response to Application Rice-Husk-Ash Amendment of Loamy Sand Soil in Ikpa Basin, Nigeria

Field plot experiment investigated the effect which different methods of application of Rice-husk Ash (RHA) amendments (viz: RHA surface mulching (RHA-MUL) and RHA mixing (RHA-MIX)) with topsoil of loamy sand had on the soil’s infiltration rate and sorptivity in a humid tropical environment. Data were obtained using double-ring infiltrometer from replicated plots analyzed using SPSS ver. 17 package for descriptive statistics, graphs, least squares regression and ANOVA. Paired sample statistics showed significant differences in infiltration rates between RHA-MIX and both the control soil and RHA-MUL, with the constant infiltration rate being significantly less, hence more water-saving in the RHA-MIX application than in both the control and RHA-MUL soils. Sorptivity and the accumulated infiltration also varied significantly. RHA-MUL did not show clear difference from the control soils. The least squares regression predicted the cumulative infiltration rate very accurately at R2 = 0.997 and 0.998 in the two treatments although the RHA-MIX converged more gradually (longer elapse-time) to the constant infiltration rate than RHA-MUL. RHA-MIX method was preferable for loamy sands. RHA amendment benefited irrigation water savings in loamy sands due to resultant improvement in capillary flow in the filter media.