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Researchers Aim to Cure Valley’s Salty Soil With $2.5M Grant From NSF

By James Leonard, UC Merced
January 23, 2020

California’s Central Valley has some of the most productive agricultural land in the world, but the accumulation of salt from irrigation water is decreasing crop productivity and threatening the industry’s long-term sustainability.

A new project out of UC Merced — funded by a $2.5 million grant from the National Science Foundation — seeks to address this problem by developing an innovative, environmentally friendly and economically feasible system to desalinate and reuse agricultural drainage water.

The project is being led by UC Merced professors Yanbao Ma, James Palko and YangQuan Chen, in collaboration with researchers from UC Santa Cruz, the University of Arizona, and the USDA’s Agricultural Research Service center in Fresno County.

Existing desalination practices don’t account for all the nuances of the food-energy-water (FEW) nexus, the researchers said. Their project will study desalination within that context, eventually leading to the development of a saltwater greenhouse system (SGS) that treats seawater or brackish wastewater for use in food production both in outdoor crops and inside the greenhouse.

The goal is to integrate the drainage-water-treatment process with the irrigation process to reduce or eliminate the long-term effects of irrigating field crops with saline water. The researchers hope to achieve this goal through six specific research objectives:

  1. Develop a cost-effective evaporator that uses agricultural drainage water to cool the SGS with no liquid discharge; recover minerals; and minimize the environmental impact.
  2. Develop a cost-effective condenser to recover water from both evaporative cooling and crop transpiration.
  3. Demonstrate efficient solar heating during daytime and radiative cooling during nighttime using a cold-water-storage tank, enabling significant energy reduction in the desalination process.
  4. Develop the SGS and identify optimal temperature and relative humidity conditions for the desalination process.
  5. Test the performance and study the FEW nexus issues in the SGS, including measuring water and energy use efficiency, crop yield and quality.
  6. Conduct a cost and performance analysis and demonstrate the technical and economic feasibility of the system in agricultural drainage wastewater treatment for food production.