Nitrogen in one form helps crops grow. In another, it can pollute drinking water, and in still another, it can change the climate.
That was the basic message at a statewide conference in Modesto on fertilizer use on farms. Experts at the two-day event, which ended Thursday, shared recent research on how to enrich the soil in ways that do not harm other resources.
A couple of hundred suppliers, academics, regulators and other interested people came to DoubleTree Hotel for the conference, the 22nd annual gathering of the Fertilizer Research and Education program.
Among them was Karen Ross, secretary of food and agriculture for Gov. Jerry Brown. Her department sponsors the research program with the Western Plant Health Association, an industry group.
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“All of us play such important roles working with growers to constantly improve our practices so that we can continue the marvelous record of productivity we have in California agriculture,” Ross said.
The program has been refining the science on synthetic fertilizers, which emerged in the 1940s and are credited with helping farmers greatly increase their yields. Critics point to pollution of air and water, and say the soil would be healthier over the long term if farmers relied more on livestock manure, crop rotation and other age-old practices.
One conference speaker talked about the threat to groundwater from nitrates, a byproduct of nitrogen-based fertilizer. It has been linked to thyroid cancer, birth defects and other problems.
Another speaker dealt with nitrous oxide, which can waft into the atmosphere from fertilized fields and contribute to the heat-trapping phenomenon known as the greenhouse effect. Many experts say this could shrink the Sierra Nevada snowpack, which provides most of the Central Valley’s water, while also raising temperatures and sea levels.
Nitrous oxide is 300 times as potent as carbon dioxide, the best-known greenhouse gas, said William Horwath, professor of biogeochemistry at UC Davis. He said farmers could reduce the emissions with careful timing and placement of nitrogen fertilizer. This can include delivering it in subsurface irrigation lines or adding substances that control the release of the element.
Howarth said that while agriculture is a major emitter, the problem would be far worse if farmland were developed into homes where people use energy and fertilizer much more intensively.
“If you save an acre of farmland from urbanization, you can reduce greenhouse emissions by 70 times,” he said.
The nitrate threat to groundwater has drawn much attention since a 2012 report from UC Davis on the Tulare Lake Basin and Salinas Valley. The concern is especially for farmworkers and other low-income residents who drink from rural water systems supplied by wells.
The assumption has been that farming is mostly to blame, but much more data has to be gathered, said research program supervisor Barzin Moradi.
“It’s becoming obvious that we need to get good at quantifying all these inputs into the root zone, and also the outputs,” he said.
The industry has been educating farmers about how to use nitrogen, phosphorous, potassium and other fertilizers efficiently. Users can save money from applying less, as long as this does not reduce their yields.
High-tech methods for carrying out the advice have emerged, such as testing of foliage to see if fertilizer is needed and monitoring of entire fields with the aid of satellites.
Earlier this month, the Environmental Defense Fund launched a campaign to get retailers and other parts of the food industry to favor grain products grown with proper fertilization.
“Our long-term goal is to make the entire U.S. grain supply sustainable – good for farmers, good for the climate and good for our waterways,” Suzy Friedman, director of the group’s Sustainable Sourcing Initiative, said in a news release.
Bee staff writer John Holland can be reached at email@example.com or (209)578-2385.