Collaborating Organizations

Bachand & Associates, UC. Davis Land Air Water Resources, U.C. Cooperative Extension and East Stanislaus Resource Conservation District

Funding Organization

State Water Resources Control Board, Proposition 50 Dairy Water Quality Program 

Project Summary

At Central Valley dairy farms, concentrated nutrients are leaching into the groundwater. Elevated groundwater nitrate levels from dairy lagoon water applications pose a human health risk and raise environmental concerns.  

Bachand & Associates worked with U.C. Davis, the East Stanislaus Resource Conservation District, and individual farmers to develop dairy Best Management Practices (BMPs) to more efficiently recycle nutrients on dairies and help control groundwater contamination from nutrients and salts.  The project utilized a combination of laboratory and field experiments to investigate the fate, transport, and cycling of nitrogen applied to silage crops. The study included (1) quantifying and understanding year-round surface and vadose zone hydrology of silage fields, (2) developing hydrologic and nitrogen budgets for fields, (3) quantifying mineralization rates of lagoon water and soil organic nitrogen, and (4) determining the availability of inorganic and organic nitrogen in lagoon water and modeling nitrogen cycling using the USDA Root Zone Water Quality Model (RZWQM). This study recommended BMPs to better manage lagoon water applications based upon data and model results.

Bachand & Associates was the primary science team contact for the East Stanislaus RCD and worked with the other collaborators in designing the field experiments.  We were responsible for the hydrologic and modeling aspects of this study.  We utilized a combination of Area Velocity Meters (AVMs), soil probes, pressure transducers, on-site precipitation data, irrigation district records and California Irrigation Management Information System (CIMIS) data to understand the field hydrology.  We were the primary liaison with farmers, interviewing them regularly to understand their cultural practices.  Working closely with the USDA model developers, Bachand & Associates utilized the RZWQM to model nitrogen transport and cycling.