The survey was conducted by UC's Conservation Agriculture Systems Institute, made up of government, academic and environmental partners. It looked at land in nine San Joaquin Valley counties that was planted in silage and grain corn, small grains for hay, tomatoes, cotton, dry beans and melons.
In 2010, conservation tillage systems accounted for about 14 percent of the acreage, an increase from about 10 percent in 2008. Minimum tillage practices were used on about 33 percent of crop acreage in 2010, up from about 21 percent in 2008.
In California, a different problem exists
In California, 75 to 80 percent of corn is a genetically engineered variety, and much of it carries Bt genes, said Kent L. Brittan, the University of California Cooperative Extension's director for Yolo County and field crops advisor.
The corn seed is purchased for glyphosate tolerance. Seed companies commonly combine the traits in their products, so the Bt genes are part of the package, even though corn rootworm is not a concern for California growers.
"We have the insect; it has never - knock on wood - been a corn pest here in California, so the resistance problem would not be an issue with us," Brittan said.