Scenario-planning system to optimize cover cropping practices for maximum infiltration and soil health in California

Prepared for the USDA Natural Resource Conservation Service California State Office in fulfillment of Conservation Innovation Grant Award Number 69-9104-18-008

Distributed changes in agricultural management practices can be an essential part of the solution for achieving groundwater sustainability. Reducing groundwater demand through increased irrigation efficiency will be an important strategy, but this only benefits groundwater reserves if producers irrigate using groundwater sources. Winter flooding of agricultural fields using excess surface waters, known as managed aquifer recharge (MAR), will also be an important tool for groundwater recharge, but it can only be implemented where infrastructure is present to divert surface waters to fields, and in years where excess surface water is available in the winter.

Beyond irrigation efficiency upgrades and MAR, there is another management practice to consider. Cover cropping, if adopted at scale, may contribute to achieving groundwater sustainability through the capture of on-field winter precipitation and stormwater. Cover cropping also has multiple co-benefits, including: the reduction of nutrient and sediment runoff, improvement of soil health and pollinator habitat, and sequestration of atmospheric carbon.

More data is needed to quantify the field-specific groundwater benefits and economic costs of winter cover cropping in California. With local USDA Natural Resources Conservation Service and Resource Conservation District partners, TFT has expanded its basin-scale assessment and prioritization system to include cover cropping in orchards and vineyards in Solano County.

In this documentation, using existing methodologies and models in a unique way, The Freshwater Trust demonstrates a methodology for

  1. the quantification of site-specific costs and benefits of using cover crops and
  2. basin-wide analysis and prioritization of cover crop implementation.

The system developed by TFT is applicable to other basins and geographies throughout the Central Valley to assess the potential for cover cropping to be included in a strategy to achieve groundwater sustainability.

Read full documentation of methods.

December 22, 2019

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