Soil Water Dynamics and Crop Water Use Under Different Tillage and Mulching Systems in the Sudan Savanna of Nigeria

This study quantifies soil water dynamics and crop water use efficiency under different tillage and mulching management combinations in the Sudan Savanna agro-ecological zone of Nigeria, covering sites in Katsina, Zamfara, and Kebbi States. Soil water availability is the primary yield-limiting factor for rainfed crops in the Sudan Savanna, where annual rainfall rarely exceeds 700 millimetres and within-season dry spells frequently coincide with critical crop growth stages. Management practices that improve soil water infiltration, storage, and use efficiency are therefore of paramount importance. This study establishes a three-factor factorial experiment at three sites testing conventional tillage versus zero tillage, mulched versus unmulched treatments, and high versus low crop residue retention levels, monitoring soil volumetric water content at three depths using TDR probes throughout two growing seasons. Crop evapotranspiration is estimated using the Penman-Monteith approach and crop water productivity is computed from millet and sorghum yield data. Findings reveal that zero tillage combined with surface mulching maintains soil water content 22 to 38 percent above conventional unmulched tillage during critical mid-season dry spells. Crop water productivity under the conservation management combination averages 8.4 kilograms per cubic metre compared to 4.2 kilograms per cubic metre under conventional management. Infiltration rate is 240 percent higher under zero tillage with mulching. The study contributes original soil water balance data for the Nigerian Sudan Savanna and recommends conservation tillage-mulching as the standard extension recommendation for the zone.

Keywords: soil water dynamics, tillage, mulching, Sudan Savanna, crop water productivity.