Assessing Soil Water Distribution under Regenerative Agricultural Practices using Three-Dimensional Computed Tomography

Nall Moonilall (PI), UC Davis Dept. of Land, Air, and Water Resources, with Sangeeta Bansal (CSU Fresno) and Cristina Lazcano (UC Davis)

The combination of climate change and limited water resources has made irrigated agriculture in semi-arid regions more difficult. Drought is becoming more severe due to rising temperatures and changing precipitation patterns, and groundwater overuse has caused groundwater depletion, reduced water quality, and reduced surface water flows. This underscores the urgency of implementing new water management strategies. One potential solution is the adoption of regenerative management practices that focuses on improving soil health to support plant growth by enhancing biological and physical processes. These practices can also provide additional benefits, such as greater water availability and infiltrability, which can help to sustain agricultural production in challenging conditions and address our research problem related to groundwater storage. Thus, the purpose of this study is to quantify the effect of regenerative soil management practices on soil hydraulic properties in irrigated agricultural systems of California. This proposal is based on the hypothesis that regenerative management practices that include no-tillage, cover crops, crop rotation and livestock grazing will enhance soil organic carbon, which in turn affects structural characteristics such as aggregate size distribution, carbon and nitrogen within the soil aggregates, pore size distribution, connectivity, and tortuosity of the soil. These soil structure modifications can potentially improve soil functions, such as water retention, storage, and water cycling. Therefore, this proposal focuses on assessing how regenerative management practices affect water distribution and soil properties in California's agricultural systems. Currently, limited research has been conducted on soil pores and aggregates and water dynamics in relation to regenerative soil management practices despite their critical importance in building soil health. This research will use X-ray micro-computed tomography (µ-CT) scanning technology to evaluate soil structure and assess soil hydraulic functions across different regenerative management systems adopted under major cropping systems in California. The project can provide researchers with insights into water dynamics (plant available water content, water storage, etc.) and improve understanding in terms of sustainability and resilience of major crops such as almonds, vineyards, and tomatoes in agricultural ecosystems.