On-Farm Flood Capture and Recharge (OFFCR) at an Organic Almond Orchard, Recharge Rates and Soil Profile Responses Groundwater Recharge Project, 2016

Abstract

Groundwater in much of California’s Central Valley (CV) has been critically over-drafted resulting in the implementation of the 2014 Sustainable Groundwater Management Act (SGMA). As Groundwater Sustainability Agencies (GSAs) work to comply with SGMA requirements and timelines, On-Farm Floodwater Capture and Recharge (OFFCR) is being studied to help increase recharge capacity. We implemented an OFFCR test on an organic almond orchard in the CV to assess achievable recharge rates attained through over-irrigation, and potential soil and water quality impacts. Irrigation water was applied via flood irrigation. We developed study sites and installed soil sensors for moisture and salinitymonitoring, took post-irrigation deep cores to assess changes in soil and porewater nitrogen and salt concentrations through the vadose zone, and monitored agronomic practices, recharge loading and crop yields.These studies were conducted on three recharge treatments with three replicated stations for each: 1) Control at about 6 inches of flooded water to meet ET as typical for irrigation (Control treatment), 2) Low Flooding of about 12 inches per irrigation application (Mid treatment), and 3) High Flooding of about 24 inches per irrigation application (High treatment).