Sustainable ag field day showcases research, points to Valley growth management

By Lyra Halprin and Bev Ransom of SAREP, with reporting by Sharon Stello of the Davis Enterprise.

Research updates on how to lessen environmental impacts while maintaining yields were presented along with a rousing talk on the importance of managing Central Valley growth at the UC Davis sustainable farming field day June 23, 2005.

The field day took place at UCD's Russell Ranch, home to many of the campus' long-term agriculture studies. More than 20 faculty, Cooperative Extension researchers, students, and growers are participating in experiments at the site and working on outreach with UC's statewide Sustainable Agriculture Research and Education Program.

California's enormous growth pressures threaten agriculture and the quality of life in the Great Central Valley but there are many things that can be done to encourage sustainability in the region, according to Carol Whiteside, president of the Great Valley Center, and keynote speaker at the UCD field day. Whiteside, a former mayor of Modesto and aide to Governor Pete Wilson, founded the Great Valley Center to focus on the economic, social and environmental health of California's Central Valley.

"We need to build a constituency for sustainability in the Valley," said Whiteside, whose organization is working to develop effective local leadership to help the region deal with the enormous pressures of a growth rate that exceeds the national and state averages, and which may result in 12 million residents in 20-30 years.

Whiteside urged the farm community to work with environmentalists and be part of the agenda to protect and sustain the Valley. To develop the economic, social and environmental well-being of an area, communities must learn new ways to deal with growth, she said. Growers should take advantage of the expanded market for organic and locally grown produce and be creative rather than allow the "demise of agriculture."

Sustainable farming project leader William Horwath, a UC Davis professor and soil biogeochemist in the land, air and water resources (LAWR) department, noted that UC researchers and cooperators are working on ag sustainability issues at the Russell Ranch location and on a 14-acre companion site. Researchers shared results on conservation tillage and the use of winter cover crops, and the use of underground drip irrigation to reduce weeds and pests, cut costs and lessen environmental impacts while maintaining yields.

The long-term agriculture studies at the Russell Ranch provide a living laboratory for students and the new Agricultural Sustainability Institute (ASI) at UCD. The ASI was launched recently with a $1.5 million endowment from the Kellogg Foundation to expand research and teaching of environmentally sustainable farming practices, including organic farming.

Tractor-drawn hay wagons moved the almost 100 participants to four field sites where researchers explained experiments designed to help growers with various rotations of tomatoes, corn, wheat, and cover crops. Each rotation is grown in organic, reduced inputs and conventional plots. Researchers are experimenting with conservation tillage and standard tillage for each method.

Field site presentations

Reduced tillage experiments are of interest to growers and others who are concerned with weed control, the use of herbicides, and water quality issues. Researchers had mixed results to report at the field day.

"We have very few weeds in this field," said Dennis Bryant, associate director of the Long-Term Research in Agricultural Systems (LTRAS) experiment, standing at a tomato plot that received reduced tillage.

According to Aaron Ristow, a graduate student researcher in the soils and biogeochemistry group, reduced tillage has not shown expected improvement for runoff water quality. He said this might be due to increased compaction under reduced tillage.

"Over the long term, however, the buildup of organic matter at the surface of reduced-till soil should lead to an increase in water infiltration," Ristow said. "We need more research to see how different degrees of soil disturbance might minimize runoff. Cover cropping significantly improves water quality and may work well in conservation tillage systems because of the ability of the cover crop to function as a ‘biological plow.’"

Drip irrigation, however, had a positive effect on weed reduction. Researchers explained that underground drip irrigation sends water directly to each tomato plant's roots, thereby avoiding unnecessary irrigation.

Horwath explained that under subsurface drip irrigation, there are fewer weeds and less need for herbicides compared to furrow irrigation, where water flows across and wets the soil surface.

"We think there may be less of the potent greenhouse gas nitrous oxide emitted," he said.

Graduate student researcher Cynthia Kallenbach, of the soils and biogeochemistry group, said preliminary results of her studies show lower carbon dioxide emissions during the growing season under subsurface drip irrigation. She believes this is because subsurface watering allows the plant roots to expend less energy to access water and nutrients and also provides less moisture to soil microorganisms at the soil surface.

Gene Miyao, a UC Cooperative Extension farm advisor for Yolo, Solano and Sacramento counties, noted, however, that underground drip irrigation might be too costly for some farmers to install. Those who do often find themselves forced to grow only high-paying crops like tomatoes year after year to pay for their investment.

On another plot, researchers have grown wheat without fertilizer or irrigation, leaving the land fallow every other year. Data show, however, that leaving the land fallow reduces the build-up of desirable organic matter but has not yet impacted yield. Substituting fallow with cover crops increases organic matter and promotes soil productivity.

"It [alternating fallow years] was the traditional farming system in California before irrigation," said Steve Kaffka, a UC Cooperative Extension agronomy specialist and LTRAS director. Kaffka talked about the possibility of changing lengths of crop rotations to "tweak" the system.

Kent Brittan, a UC Cooperative Extension farm advisor for Yolo, Solano and Sacramento counties, said farmers in the Midwest and Eastern states have been using no-till techniques for about 30 years with much success. But they grow only one or two crops, usually wheat and corn, which is not profitable in California where growers are forced to diversify.

"The problem is, California farmers rotate crops and their yield ‘takes a hit’ when they try reduced tillage," Brittan said. "There's no easy answer. We're continuing to experiment with different combinations of methods."

Tom Lanini, a UC Cooperative Extension specialist in weed ecology, addressed the effect of reduced tillage on weeds.

"Weeds are what's killing us in conservation tillage," he said, noting that other methods of weed control become necessary.

In a search for solutions to increased weed populations in reduced tillage fields, Lanini has had some success reducing weeds with clove oil and other non-toxic herbicides.

After the field discussions, Karen Klonsky, UC Cooperative Extension specialist in the UCD agricultural and resource economics department, discussed the economic impact of conservation tillage management systems.

"Our analysis demonstrates the potential for conservation tillage to decrease operating costs for both processing tomato and corn," she said.

She noted, however, that despite these encouraging findings, conservation tillage would not be attractive to growers unless yields are comparable to those under standard tillage.

"Our challenge in the coming season is to modify the systems to improve yields without compromising the spirit of conservation tillage," she said.

Farmer panel

A panel discussion featured local farmers talking about promising methods they've tried, and their impressions of the usefulness of conservation tillage.

Tony Turkovich, owner of Turkovich Ranch in Winters, said he has tried a diverse range of crop-management techniques. The challenge, he said, is different soil conditions make it impossible to employ the same methods on each field. He's pleased, though, to see university researchers investigating alternative methods.

"We're glad to see them pushing the envelope to see what can be done," Turkovich said.

First-generation farmer Scott Park of Meridian, who has been using cover crops for 16 years, summarized the grower's point of view by saying he is interested in sustainability if he can "make the ground better and still make a buck."

Bruce Rominger, who farms with his family in Winters, echoed the importance of good economics, and said there is a big learning curve working with reduced tillage.

"If I produce less per acre with new methods, I can't do it," he said.

Grower Frank Muller stressed the importance of weighing new production practices for individual farms and told other farmers to ask, "does it work for you?" He noted that profitability is a key factor for younger farmers, as is the ability to have some time off from the daily grind of farming.

For more information about conservation tillage research, see the Sustainable Agriculture Farming Systems (SAFS) Web site at http://safs.ucdavis.edu. Additional information on the LTRAS site is at http://ltras.ucdavis.edu/. For more information on the Great Valley Center, see http://www.greatvalley.org/.