Performance Evaluation of Selected Irrigation Water Management Tools Under the Surface Drip Irrigation System in Southeast Botswana

This study evaluated the performance of four irrigation water management tools, tensiometers, time domain reflectometry (TDR), Chameleon soil water sensors, and wetting front detectors (WFDs), for monitoring soil water dynamics under a surface drip irrigation system in South East Botswana. The study was conducted at the Botswana University of Agriculture and Natural Resources (BUAN) research farm. Soil moisture dynamics were monitored at 5, 15, 25, 40 and 60 cm depths, while a digital smart water meter was used to quantify seasonal irrigation water use by a planted maize crop. Tensiometers detected a significant increase in soil-water tension from 7.00 kPa at 25 cm to 14.55 kPa at 40 cm (t(39) = 10.53, p < 0.001), demonstrating sensitivity to depth-related changes in soil-water availability. TDR similarly detected a significant difference in volumetric water content between 5 cm (11.07%) and 15 cm (12.93%) (t(29) = −10.44, p < 0.001), indicating reliable quantitative monitoring of soil-moisture variation. WFDs showed significant depth-related responses (χ²(3) = 41.267, p < 0.001), while Chameleon sensors detected significant differences in soil-water status among 5, 15 and 40 cm depths (Friedman χ²(2) = 14.71, p < 0.001). Reported seasonal irrigation water use was 8.975 m³, and maize grain yield was 2.17 t/ha. The four tools demonstrated sensitivity and responsiveness to soil-water dynamics as well as demonstrating great potential for on-farm irrigation management. Although these tools provided complementary information ranging from quantitative soil-water measurements to simple indicators of wetting-front movement and soil-water dynamics, when they are integrated they can support adaptive, soil-water-based irrigation scheduling and more efficient use of irrigation water in water-scarce environments such as Botswana, contributing to sustainable water management under Sustainable Development Goal 6.