Investigating Soil Water Dynamics to Improve Agriculture: Namibian Land-Use Systems Under Drought

Water scarcity presents a critical limitation to sustainable agricultural productivity in the semi-arid region of northern Namibia, where sandy soils and irregular precipitation challenge subsistence farming systems. Regional land-use practices significantly alter soil water dynamics under drought conditions. However, field-based quantification of the key parameters that define these dynamics remains limited. This study investigates the impacts of land-use systems, notably, conservation agriculture (CA), traditional agriculture (TA) and woodlands (W) on soil water dynamics through in situ assessment of evapotranspiration, soil water content and infiltration during the 2024 pearl millet growing season. Using a closed-chamber method, time-domain reflectometry (TDR) sensor and double ring infiltrometer under consistent weather conditions, we demonstrate that CA significantly enhanced soil water dynamics. Particularly within riplines, CA reduced infiltration and increased soil water content with very large effect sizes (Cohen’s d = −2.45 and 1.30, respectively), compared to TA. Evapotranspiration did not differ significantly between CA and TA. CA exhibited evaporation dominated water losses with consistently low transpiration-to-evapotranspiration (T/ET) ratios (median = 0.07) across all investigated farmlands, indicating limited crop water uptake. These findings provide empirical evidence of CA’s role in enhancing soil water conservation in dryland systems, reinforcing the imperative for water conserving management strategies under intensifying climatic constraints.