Posted 28 August 2006. Crop Management.
Conservation Tillage Helps Growers Save Time, Money, the Environment
University of California at Davis www.aes.ucdavis.edu
Davis, California (August 15, 2006) - As fuel prices rise and agricultural profit margins narrow, California farmers may find some relief with conservation tillage, in which growers reduce the number of times that they drive tractors across their fields. Common in the Midwest, conservation tillage is relatively new to California, and UC researchers are working to adapt it to local crops and conditions.
The July-September 2006 issue of the University of California's California Agriculture journal includes two peer-reviewed research articles and related news coverage on the pros and cons of conservation tillage in California. The full articles are posted online at californiaagriculture.ucop.edu.
"Conservation tillage is not like previous agricultural innovations," says Jeff Mitchell, UC Cooperative Extension vegetable crops specialist at UC Davis. "Farmers are not just introducing a single technology; they are changing their entire system of farming. Farmers are doing the frontline trouble-shooting work with support from scientists and agricultural industries."
While some innovative California growers have adapted conservation tillage to the state's unique climate and soil conditions, the practice is still relatively uncommon here. (A seminar with California growers who have successfully reduced their tillage will be held Aug. 8 in Sacramento [see below]; the UC Conservation Tillage workgroup has nearly 500 members statewide; see http://groups.ucanr.org/ucct)
Growers continue to till the soil for a variety of agronomic reasons, Mitchell says, including to manage weeds and diseases, loosen compacted soil and allow more-efficient furrow irrigation.
However, Mitchell says the potential benefits of conservation tillage are numerous. They include water conservation, dust suppression, reduced pesticide runoff into surface water, lowered labor needs and costs, and fuel savings. In addition, limiting tillage helps to keep carbon in the ground and prevent the buildup of greenhouse gases in the atmosphere.
In California Agriculture, Mitchell and colleagues report on a field study of seven different tillage methods in two back-to-back cotton crops in the San Joaquin Valley, with and without an intervening cover crop. While cotton yields were for the most part comparable in all the tillage systems studied, the reduced-till systems decreased the number of tractor operations by anywhere from 41 percent to 53 percent, fuel use by 48 percent to 62 percent and overall production costs by 14 percent to 18 percent.
The other peer-reviewed study published in California Agriculture examines the effects of different tillage methods on soil quality in a typical San Joaquin Valley cotton-tomato crop rotation, with and without cover crops. The 4-year study found that conservation tillage alone improved some soil parameters, such as bulk density and the availability of nitrogen and phosphorus, but it also significantly increased concentrations of salt and potassium at the soil surface. However, cover cropping in conjunction with conservation tillage mitigated most of the deleterious effects on soil quality.
"In the low-rainfall regime of the San Joaquin Valley, farmers may benefit more from cover cropping in combination with conservation tillage to maintain soil fertility, as opposed to conservation tillage alone," wrote authors Jessica Veenstra, former UC Davis researcher, and colleagues.
UC Davis soil scientist William Horwath noted that the effectiveness of conservation tillage varies considerably with crop type, agronomic practices and growing conditions. "California agriculture is more intensive than in the Midwest, which is primarily grain crops and is thus more amenable to conservation tillage," Horwath says. "Here we have many varied crops requiring specific agronomic practices. Itís not a clear-cut decision, and it may not be for everyone."
Seminar: A free workshop featuring California conservation tillage innovators will be held at 7 p.m. on Aug. 8 at the Hyatt Regency in Sacramento. For more information, go to: http://news.ucanr.org/newsstorymain.cfm?story=820