Water Resources Research Act Program

Details for Project ID 2016CA358B

Using Soil Exopolysaccharides (EPS) to make California grapes more drought-adapted

Institute: California
Year Established: 2016 Start Date: 2016-03-01 End Date: 2017-02-28
Total Federal Funds: $12,396 Total Non-Federal Funds: $6,632

Principal Investigators: Joseph Blankinship

Project Summary: As highlighted by the current historic drought and forecasts for future climate change, California agriculture will only be sustainable by adapting to drought. For example, in order to support the rapid expansion of grape vineyards, Californians need to develop water conservation strategies from the “ground up.” I propose a soil-based solution for drought adaptation. If water retention and nutrient availability can be improved in dry soils, it may be possible to conserve large amounts of water by reducing irrigation frequency during drought. Various synthetic soil surfactants and hydrogels are commercially available to increase water infiltration and retention, but these products can have toxic effects in the environment and they are not intended to increase nutrient diffusion to plant roots. As an alternative, we propose to amend vineyard soils in the greenhouse with an exopolysaccharide (EPS), xanthan gum, which is naturally secreted by soil bacteria, commercially available in bulk quantities, and a non-toxic FDA-approved food additive. When mixed with soil, xanthan is known to be both a superb “sponge” for long-lasting water retention and “highway” for the diffusion of resources. However, there are no studies that have investigated the potential benefits of soil EPS on plants. Does more soil EPS mean greater water and nitrogen (N) availability for plants? An undergraduate researcher and I will grow grape plants in a greenhouse with varying levels of xanthan and water to see whether soil EPS can maintain N supply and plant health while reducing the need for irrigation.