Delta Sac-SJV Rice Evaluation III

Rice culture in the Sacramento-San Joaquin Delta to mitigate past agricultural impacts, improve water quality and sequester carbon, 2011 - 2016

Collaborating Organizations

Bachand & Associates, UC Davis, Hydrofocus, USGS, Stillwater Sciences, Wetlands and Water Resources, UC Berkeley, U.C. Cooperative Extension, Delta Science Center

Funding Organization

USDA AFRI Grant Program

Project Description

About two thirds of the 740,000 acres in the Sacramento-San Joaquin Delta (Delta) is agricultural land. The drained peat soils of the Delta have provided fertile soils for agriculture since the late 1800s when these lands were reclaimed from existing wetlands. Since then, the Delta environment has dramatically deteriorated as evidenced by subsidence. 2.5 billion m3 of peat soils have oxidized causing subsidence up to 20 feet or more below sea level on many Delta islands.

Subsidence is indicative of other severe consequences including extensive greenhouse gas emissions and degradation of water quality. Subsidence and groundwater loss necessitated the construction of a 110-mile levee network and the development of the California State Water Project. If current agricultural practices remain unchanged, consequences will increase in severity. Peat oxidation will continue, resulting in further subsidence over decades; GHG emissions will continue, with an additional estimated 158 Mtonnes CO2eq of C and N2O lost to the atmosphere by 2050; levee failure risks will increase due to levee deterioration and the increasing hydraulic gradients across the levees; water quality degradation will continue. Clearly, agricultural practices need to change in the Sacramento – San Joaquin Delta region.

The goal of this project was to demonstrate rice-based cropping systems as an agricultural solution in the Delta. The solution has the following environmental benefits: mitigating subsidence, GHG emissions, and soil fertility loss, whilst concurrently reducing water supply loss and protecting water quality. These mitigation strategies benefit agriculture downstream of the Delta. This project assessed both the technical, engineering, logistic, economic and policy constraints and opportunities to expanding rice throughout the Delta and the regional and state-water project scale impacts.

This project was awarded in 2011 under the National Institute of Food and Agriculture Climate Change grant program.

Publications

1. Bachand, P.A., Bachand, S.M., Stern, D., Deverel, S. and Horwath, W.R., 2018. Rice Drain Management to Reduce Seepage Exports in the Sacramento–San Joaquin Delta, California. Journal of environmental quality 47(5), 1186-1195.

2. Horwath, WR. L. Butler, B. Linquist, D. Baldocchi, P. Bachand, S. Deverel, J. Fleck, S. Siegel, and A. Merrill. 2012. Rice culture in the Sacramento-San Joaquin Delta to mitigate past agricultural impacts, improve water quality and sequester carbon. Soil Science Society of America Annual Meeting. October.

3. N. Stern, S. Bachand, S.Deverel, W.R. Horwath, P. Bachand. Rice Drain Management to Reduce Seepage in the Sacramento-San Joaquin Delta. Bay Delta Conference, October 2014. Sacramento, CA.