Agriculture

Group studies new way of dealing with dairy wastewater

De Jager Farms, southeast of Merced, uses drip irrigation to water plots of feed corn, seen during a tour Aug. 26, 2015. The project also involves Netafim USA, which makes drip irrigation supplies and has a Fresno branch, and Sustainable Conservation, a San Francisco group that helps businesses protect the environment.
De Jager Farms, southeast of Merced, uses drip irrigation to water plots of feed corn, seen during a tour Aug. 26, 2015. The project also involves Netafim USA, which makes drip irrigation supplies and has a Fresno branch, and Sustainable Conservation, a San Francisco group that helps businesses protect the environment. Modesto Bee file

I drove out past Merced last year to see a dairy farmer testing a new idea. He irrigated 40 acres of feed corn with drip lines, which are much more common in orchards and vineyards than annual crops.

The lines did more than conserve water. They delivered fertilizer, in the form of nitrogen-rich wastewater from one of the farm’s manure lagoons. Such precise application could reduce the risk of pollutants seeping into drinking-water aquifers – a concern with the widespread practice of flood irrigating with lagoon water.

The research is moving into a new phase, thanks to an $833,000 grant from the U.S. Department of Agriculture. It went to Sustainable Conservation, a San Francisco-based group that will look into how to spread the practice to other dairy farms in the Central Valley. Project manager John Cardoza is working on it from the Modesto branch office.

The first demonstration took place over two years at De Jager Farms, about 6 miles southeast of Merced in northern Madera County. The lagoon water was filtered to remove some of the manure and sand, then mixed with fresh water and and sent through drip lines provided by Netafim USA for the project.

Flood irrigation typically takes about 40 vertical inches of water over the growing season for corn, farm manager Nate Ray said at the demonstration last year. He needed only 28 inches with the drip lines.

Ray said he harvested about 20 percent more corn per acre thanks to the efficient application of the nutrients. And the irrigation happens much faster than the 15 or so hours it can take to flood a field completely.

The next phase will take place over three years on 217 acres total at three dairy farms. De Jager is one of them. The others are in Madera and Kern counties.

The grant came from the Conservation Innovation Grants program, which seeks to spur fresh thinking on how farmers and ranchers can produce food while protecting the planet. In this case, it’s keeping drinking-water wells from being tainted by nitrates, a form of nitrogen that can make people sick. Dairy farmers say they apply only enough of the nutrient to be taken up by the crops, but the concern remains in some quarters.

“With our Conservation Innovation Grant from the USDA,” Cardoza said by email, “we’re hoping to scale this type of farming practice across the Central Valley to save water, reduce nitrate leaching to groundwater, improve the health of local communities, and boost crop yields.”

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