Farmers do their part for Earth Day

Ag industry actively conserves, recycles all year long

Bob Krauter
Capital Press California Editor

April 20, 2007

SACRAMENTO - As caretakers of nearly one-third of the state's 100 million acres of land area, California farmers and ranchers actively recycle, compost and re-use natural resources as part of their daily routine.

For many farmers, the observance of Earth Day on April 22 will be just another day in their year-round endeavor to conserve water, promote habitat and produce food and an array of other agricultural products with Mother Nature's help.

Clarksburg wine-grape grower Ken Wilson employs a variety of earth-wise techniques that include putting up boxes for owls and perches for hawks to encourage them to watch over vineyards for mice, gophers and squirrels. He also maintains cover crops to keep vineyards cool during the hot summer months.

"It keep the dust down and the mite populations in check. We have made big improvements in cover crops. It helps with erosion because we get pretty heavy rains out in this area," Wilson said. "The cover crops create habitat for predatory-type insects and we need those to help feed off the bad insects."

His use of cover crops extends to levees in his area of the Sacramento River Delta to control erosion and keep weeds in check. His cultural practices include shoot thinning to cut the incidence of disease and the need for chemicals.

"We probably take out about half of the shoots, which gives more aeration in the vines and reduces fungus diseases," Wilson said. "We also do leaf-pulling around the fruit clusters. By aeration and more sunlight, that's what fungus does not like, so you will have a much higher quality fruit cluster for the winery."

California 's $4 billion dairy industry works also on environmental challenges. A major one is disposing of manure from nearly 2 million dairy cows.

Kings County UC Cooperative Extension dairy farm advisor Carol Collar said some dairy farmers use methane digesters to convert manure into biogas. Many dairy farmers are employing methods to separate solids from the liquid manure that flows into on-farm lagoons.

Collar is working on a research project that is analyzing the use of aerators to increase oxygen and cut methane emissions. Dairy farmers are increasingly interested in refining their composting techniques to reduce pathogens and improve nutrient management of land-applied manure for crop production, she said.

Dairy farmers are also conserving water on dairies.

"Some free-stall operations where they do good job of keeping the beds clean and some are using sand bedding so the cows are really clean and don't need to be washed as much and use as much water," she said. "When they reduce water used, it means less pumping and less electricity that are used."

Many farmers have long practiced water efficiency and conservation. It is estimated that California farmers and ranchers use roughly 43 percent of the state's developed water supply of 78 million acre-feet annually. This year, a meager Sierra snowpack could place additional pressures on farmers to conserve and innovate with tools such as sub-surface drip irrigation.

Will Horwath, a UC-Davis professor, said the use of sub-surface drip in the Central Valley is increasing but still represents less than 15 percent of all irrigation. The method has the potential to reduce tillage compared to furrow irrigation. It can also help reduce greenhouse gas emissions, Horwath said.

"If you use less water, you can reduce the conditions necessary to emit greenhouse gases," Horwath said. "The furrow irrigation wetted the entire soil profile creating more areas that could release greenhouse gases. Sub-surface drip spoon-feeds plants and does not wet as much of the soil profile."

Horwath said farmers in many commodity segments have adopted sub-surface drip irrigation. Processing tomato growers have significantly increased their use of the technology, but farmers of melons, peppers and other vegetables have followed suit, Horwath said.

"You can potentially use less water. We showed up to half as much water can be used," he said. "We haven't experimented with the amount of fertilizer, but adding the same amount of fertilizer between the traditional way and sub-surface drip, you get a significant reduction in nitrous oxide emissions."

Johan Six, a UC Davis plant science professor, is working with fellow researcher Steven De Gryze at the university's Agroecology Laboratory on evaluation of the potential and economic value of carbon sequestration in the soil. He said use of cover crops, reduced tillage and lower rates of nitrogen fertilizer can have benefits for storing carbon and reducing emissions of nitrous oxide.

"Nitrous oxide emissions are a potent source of greenhouse gas emissions and even with positive steps to sequester carbon, you can quickly offset that with nitrous oxide emissions," Six said. "If you reduce your fertilization in a given year, that nitrous oxide is never going to appear. That is a permanent reduction."

Six and De Gryze are trying to develop economic models to determine the value of carbon sequestration on farms and the potential for farmers to sell carbon credits derived from their carbon sequestration practices.

Just a few years ago, discussion of carbon credits for farmers' efforts would not have been a reality, but Six said there appears to be the political will and momentum to seriously consider the issue now.

"If we really want to deal with climate change, it will (require) going through these kinds of schemes," Six said. "We are talking about 5 to 10 percent of emissions that need to be reduced that we can handle with some things in agriculture. So it is clear there are other kinds of measures that will have to be done."

Bob Krauter is the Capital Press California editor based in Sacramento . His e-mail address is bkrauter@capitalpress.com.  

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