Evaluation of Soil Moisture Conservation Practices to Reduce Agricultural Dependence on the Ogallala Aquifer

Abstract

Background: Sustainable groundwater management needs to have complementary measures that have direct effects of improving soil water retention and lower crop evapotranspiration demand at the field level. Precipitation conservation practices that have been applied to soils can provide a viable avenue for decreasing irrigation reliance by heightening productive use of water and cutting down on unproductive water seepage. Reduced groundwater within the Ogallala Aquifer is a risky factor for the sustainability of irrigated agriculture in the U.S. High Plains. Aim: This study critically assesses the concept of soil moisture conservation methods as a possible solution to limit agricultural reliance on groundwater extraction from the aquifer. Methods: The systematic review was conducted as per the Preferred Reporting Items on Systematic Reviews and Meta-Analyses (PRISMA) guidelines. There were extensive searches conducted in key scientific databases to find peer-reviewed research studies that analysed the influence of conservation tillage, cover cropping, management of residues, deficit irrigation, and precision irrigation on soil moisture retention and irrigation demand in semi-arid agroecosystems. Following the screening and eligibility test, the qualified studies were then synthesised in a qualitative and, in some cases, quantitative manner to evaluate the effects on soil water dynamics, crop yield and water use efficiency. Results: The evidence suggests that, based on most climatic conditions, integrated soil moisture conservation strategies can substantially enhance the retention of soil water, minimise evaporation losses and mitigate irrigation needs without huge yield reductions. Conservation tillage, along with residue retention and optimal irrigation timing, demonstrated the most reliable results on the reduction in groundwater abstraction. The results prove that water management methods based on soil can become significant when regulating the depletion rate of the aquifer when applied at large scale. Conclusion: The barriers to adoption, climatic variability and site-specific soil conditions, however, have an effect on the performance outcomes. The policy incentives and extension support are also needed to improve uptake and realisation of groundwater extraction reduction.