Impacts of water optimization practices on soil health and soil water infiltration

Water scarcity is a major challenge for agriculture in arid and semi-arid regions. This study evaluates the long-term effects of deficit irrigation (DI) and land management practices, including no-tillage (NT), crop genetics, crop types, and cover cropping (CC), on soil health and water infiltration. Field experiments were conducted from 2019 to 2024 at three sites in Utah, USA, to study the effects of conservation practices in Wellsville, Vernal, and Cedar City. Two irrigation levels (100% and 50% of crop evapotranspiration) were applied using mid-elevation spray application sprinklers on a lateral irrigation system. Five cropping systems were evaluated: tilled corn ( Zea mays ), NT corn, tilled corn with CC, NT drought-tolerant corn with CC, and conventional alfalfa ( Medicago sativa ). Soil health was assessed using soil organic matter (SOM), soil respiration, autoclave citrate-extractable (ACE) protein, permanganate oxidizable carbon (POXC), and aggregate stability. Field-saturated hydraulic conductivity (K fs ) was measured using dual-head infiltrometers. Deficit irrigation had minimal effects on SOM (except at Vernal, 10.2% increase under DI) and aggregate stability. Soil respiration was 28% higher under full irrigation at Vernal, and ACE protein decreased from 1.57 to 1.41 g kg -1 under DI at Cedar City. Conservation practices such as NT and perennial alfalfa systems also had greater microbial activity across sites. Cover cropping increased K fs to 24.62 cm h -1 , compared with 5.55 and 3.42 cm h -1 under conventional tillage and NT at Vernal in 2023, respectively. The results demonstrate that moderate reductions in irrigation can be compatible with maintaining soil health in cooler regions, whereas warmer environments may require more conservative water reductions.