Agricultural Expansion-Induced Infiltration Rate Change in a West African Tropical Catchment

Abstract

Land use and land cover in the Dano catchment is characterized by a rapid conversion from seminatural vegetation (fallow) to agriculture (cropland). The study compares both the saturated (Ks) and the unsaturated (Kh) hydraulic conductivities under cropland and fallow in the catchment to gain insights into the effect of the current land use on soil water dynamics. Hydraulic conductivity wasmeasured underforty-two (42)pairsofadjacentcropland-fallowplotsusingaHoodinfiltrometer.Ks,Kh,bulk density,andsoiltexturewerefurthercomparedusingapairedtwo-tailedStudent’st-test(p � 0.05).Theresultsshowedthatboth KsandKharehighlyvariableirrespectiveofthelandusetype(coefficientofvariation>100%).TheresultsalsoshowedthatKswas significantlyhigher(1.16-foldonaverage)underfallowcomparedtocropland.AsforKh,theresultsshowedthat,from−2cmto zerotensionheads(h),Khundercroplandandfallowisnotsignificantlydifferent;however,asthesuppliedtensiondecreasesupto the saturation state, Kh under fallow becomes statistically higher compared to cropland. No significant difference was found between soil textures and bulk density under cropland and fallow meaning that the observed differences of Ks and Kh under croplandandfallowwerecausedbylanduseandnotpreexistingdifferenceintexture.Theseresultssuggestanincreasingriskof erosion, soil fertility reduction, and flood in the catchment because of agricultural land expansion.