Conservation tillage, like happiness, means different things to different people, and agricultural and resources professionals found plenty of diversity to whet their interests recently at Five Points, Calif.
The Western States Conservation Tillage Conference drew attendees from throughout California, Arizona, and Oregon to see everything new in equipment and methods under the San Joaquin Valley sun.
Perhaps not yet a household word, conservation tillage, or CT, in its various permutations, generally means either no-till, ridge-till, or strip-till operations, with or without cover crops. Advocates concede it has not been a success for all crop and locations, but they are quick to add that much is yet to be learned.
Adoption of CT has been spurred by desire for fewer passes across a field, reduced fuel use, prevention of soil erosion by water and dust, and preservation of carbon in the soil. In some instances, threats of air pollution regulation or shortages of water have also given strong urgency to experimentation.
While terminology and best methods may still be clouded, observers say more acreage across the U.S. is being farmed with some sort of CT than by standard tillage practices.
The conference, expected to become an annual event, filled two days with simultaneous presentations and in-field demonstrations, along with tours for some 250 attendees at the University of California's West Side Research and Education Center near Five Points.
In an overview of CT in California, Robert Hutmacher, UC cotton specialist, said while statistics are being accumulated with multi-year trials, a work group of university and resource agency experts polled nearly 300 SJV farmers for their perceptions of CT.
“We got a very broad range of comments and some of them will help determine future directions for research,” he said.
Some 60 growers, representing more than 144,000 acres responded, nearly half of them saying they had practiced some method of CT, mostly as minimum tillage or some routine that amounted to fewer passes than the standard.
Forty-five present said they were familiar with the general concepts of CT, 35 percent said they were quite familiar with it, and the remainder indicated they had either little or no familiarity with it.
Touching on double cropping cotton with tomatoes, Hutmacher said trials are under way with various methods and cover crops. One result so far is that more crop residue is not necessarily a good thing. Pink bollworm requirements in the SJV necessitate that cotton roots be killed and displaced, so no-till operations are not possible and a pass with a shredder-bedder is required.
Problems with stand establishment and early crop vigor in cotton have dogged the trials with CT, although some improvements are being seen as the studies continue.
Tomato trial results
However, data from four years of tomato trials, he said, show that CT without cover crops can establish adequate transplants for yields comparable to traditional practices. Studies continue to develop systems for the best economics and greatest reduction in tillage.
Steve Husman, University of Arizona Cooperative Extension agent for Pinal County, said on-farm CT research during 2002 and 2003 demonstrated that tillage operations could be reduced for barley-cotton double crop programs at Coolidge, Marana, and Maricopa.
Coming out of cotton, they could go with two passes, shredding and planting, and from grain to cotton with one pass, either harvest or herbicide burn-down, before planting into the residue. Conventional practice for going from cotton to grain might take as many as seven passes.
Some participating growers have “parked” their rippers and heavy plows in favor of CT methods.
“It won't be surprising that we found a lot of inconsistencies in yields and economics between systems across different locations. We are comfortable saying there's no question that CT systems needed fewer passes and therefore lower labor and lower ownership (tractor) costs,” he said.
Among the findings is the need for higher seeding rates for barley for acceptable stands. Current studies are aimed at finding other higher-yielding grain crops.
Husman was optimistic that “brainstorming” among Central Arizona farmers will continue to be successful in finding solutions for adapting innovative practices.
UA weed specialist Bill McCloskey, who worked with Husman and others in the studies, said spot spraying with weed sensing equipment used with CT is promising but has to be evaluated further as to whether the reduced herbicide costs can balance with increased capital costs of the equipment.
For a CT perspective from Oregon, John Luna, associate professor of horticulture at Oregon State University, Corvallis, said trials with strip tillage in the Willamette Valley, mostly on sweet corn, produced the desired effects of CT, along with improved soil biomass from cover crops and yields comparable to conventional tillage.
Centerpieces of his work were a modified rotary strip tiller and a shank-coulter tiller. Tillage equipment was set to the row spacing of planters and required either row markers or GPS systems for precise alignment. Two tillage passes were required for a satisfactory seedbed, and a final pass was made with a cultipacker to smooth and firm the seedbed.
Participating growers have built or modified their tillage equipment to suit the practices, and Luna said the transition to strip tillage requires patience in mastering a learning curve.
And there was frustration along the way. The need to operate rotary tillers at 2-1/2 miles per hour caused some growers to adopt the faster shank-coulter system set at about 14 inches.
A curious by-product of the experiments, he noted, was the growers found ways to reduce the number of passes in their conventional routines.
Luna also studied the use of cover crops and found the native California plant, Phacelia, planted with common vetch, to be easier to work into the soil than cereal residue, which tends to ball up. Phacelia provides nitrogen and its dried fibrous foliage and roots shatter easily. “If there's too much residue out there, the tiller just can't do its job.”