Move to regulate farms to ease nitrate problem
- May 17, 2010
Farmers and state officials are exploring solutions to nitrate pollution in heavily impacted parts of the state, including regulating Central Valley farmers who rely on commercial fertilizer.
"The largest problem is irrigated agriculture," said Jean Moran, professor of earth and environmental science at ÂãÁÄÖ±²¥ and a former research scientist at Lawrence Livermore National Laboratory.
"It covers a much larger area, it's a constant input of nitrates in groundwater and you have constant irrigation and over-irrigation, which drives the nitrates deeper into the groundwater. But if you look for new evidence of regulations on nitrate issues in groundwater, you just don't find them."
One option would require farmers to install mandatory groundwater-monitoring wells on each farm and report back to the state - a controversial idea that regulators say is unlikely to take root.
"Monitoring wells is expensive, and individual growers should not take on that expense if there is no demonstrated proof that whatever may be tested has anything to do with (them)," said Renee Pinel, CEO of the Western Plant Health Association, which represents agricultural retailers and fertilizer manufacturers.
In 2007, the state appropriated $2 million to assess whether to help low-income communities get access to safe drinking water in the southern Central Valley and the Salinas Valley - two of the most nitrate-saturated parts of California.
Another set of recommendations will focus on developing a cleanup plan for both regions. Money for the project was set aside in Proposition 84, the Safe Drinking Water, Water Quality and Supply, Flood Control, River and Coastal Protection Bond Act of 2006. But a freeze on Prop. 84 bond funding means the project has yet to begin.
One way to stop the nitrate cycle is to use less fertilizer. Depending on the type of crop and soil conditions, some plants only use half of the fertilizer a farmer applies - leaving the rest to evaporate or percolate into the groundwater.
A small group of lettuce farmers in Monterey County has discovered it's possible to save money on fertilizer, cut back on water and reduce nitrates without sacrificing crop yield.
Using a "quick nitrate" test provided by the UC Cooperative Extension, growers can gauge how many nitrates are in the soil and use only as much fertilizer as their lettuce needs to grow.
Michael Cahn, a UC Cooperative farm adviser, says he helped one company use 70 pounds less fertilizer per acre and get the same yield. A benefit of using less fertilizer is that less water is needed to grow the lettuce.
Some companies have developed "slow-release" fertilizers that limit the amount of nitrogen that breaks down into ammonium and nitrates. These fertilizers are mostly used by plant nurseries and strawberry farmers, according to Cahn.
Organic fertilizers are another source of nitrogen that leaches fewer nitrates into groundwater, but they are not widely used by growers because they are more expensive.