This study seeks to determine the long-term feasibility of diverse, cereal-based, no-till cropping systems for low-rainfall areas of the inland Pacific Northwest. Specifically, it will:
1. Evaluate and compare three long-term no-till annual spring cropping systems
2. Measure the effects of the three annual spring-sown rotations on root disease, soil moisture dynamics and grain yield for wheat
3. Record weed species shifts and weed ecology related to no-till seeding and alternative spring cropping systems; screen herbicides for controlling weeds in broadleaf crops
4. Document the long-term cumulative effects of minimum-disturbance no-till sowing practices on physical and biological properties on the soil surface
5. Evaluate agronomic and economic potential of diverse annual spring cropping compared with winter wheat/summer fallow
6. Through field days, research reports and winter meetings, demonstrate and promote no-till and alternative farming practices to growers and agriculture support personnel
After trying a variety of spring crops in rotations with a no-till operation, the SARE-funded project found the best results were staying with continuous cereals.
The alternative crops failed to provide a break in the major disease problem, Rhizoctonia root rot. Indeed, the project found, some crops, like safflower, are better carriers of Rhizoctonia than wheat or barley. Also, deep-rooted crops use more soil moisture than wheat or barley, which affects moisture available for the next crop. While mustard and canola show some promise, finding adapted varieties is a challenge, and the crops are susceptible in the seedling stage to spring frost damage.
The project was designed for plots ranging from 20 to 80 acres and planted with crops that have shown some promise of being adapted to the region, including safflower, mustard, flax, triticale and oats.
Limited seed, severe spring frost and drought altered some of the crops and rotations. After consulting with an advisory committee in January 2001, the project was expanded to add two four-year rotations, two two-year rotations and two continuous rotations for study from 2001 to 2004. The four-year rotations are two years of soft white winter wheat followed by two years of soft white spring wheat and soft white winter wheat, spring barley, yellow mustard and soft white spring wheat. The two-year rotations are soft white winter wheat followed by spring barley and hard white spring wheat followed by spring barley. The continuous rotations are soft white spring wheat and hard white spring wheat.
Yields were low at all sites in 2001 because of drought. Vast areas of drought-stressed wheat surrounded green patches of healthy spring wheat. The cause of these “leopard spots,” which occurred widely throughout the Pacific Northwest, remains a mystery. In many instances, winter wheat seedlings that survived the winter were killed by Rhizoctonia root rot in early spring.
Weeds. The major weeds at the Jirava site during Phase I were Russian thistle, mares tail, prickly lettuce and tansy and tumble mustard. Russian thistle was by far the most troublesome weed at both sites. Broadleaf weed infestation was much higher in safflower and yellow mustard, which have no labeled herbicides, compared with cereals, where in-crop herbicides were effective.
Rhizoctonia root rot. Despite differences in crops and rotations, the incidence and severity of root rot were similar, or the same, on wheat whether the cropping system was continuous wheat, a two-year barley-wheat rotation or a four-year safflower-mustard-wheat-wheat rotation. It appears that broadleaf crops provide no benefit for control of Rhizoctonia root disease and leave less soil water available for the ensuing cereal crops, begging the conclusion that growers in the low-precipitation areas of the inland Pacific Northwest are better off planting continuous cereals. A short period of fallow, the project report says, can greatly reduce the severity of this disease.
The study demonstrated numerous benefits from no-till cropping, including reduced erosion, cleaner air and enhanced soil quality. With no fieldwork during nesting, bird habitat is improved. The amount of soil saved from reduced wind erosion is hard to measure, but USDA-ARS estimates that as much as 50 tons per acre can be lost during some windstorms.
Despite these advantages, the economics are still not up to the bottom line of the summer fallow rotations.
FARMER ADOPTION AND DIRECT IMPACT
Most farmers in the area continue to practice the traditional winter wheat-summer fallow rotation. About 10% of the land area is in a three-year rotation of winter wheat, spring cereal, summer fallow. Less than 1% of the land is continually cropped on an annual basis. Still, farmers and scientists are highly interested in no-till, which is viewed as the farming practice of the future.
Neighboring farmers and visitors have responded in a variety of ways. A core of farmers doubt success with continuous cropping, preferring to see more research on summer fallow. Others are excited at the no-till work.
“We have had visits from scientists, students and farmers from many areas of the world,” says project coordinator Ron Jirava. “They have been generally impressed by what we are accomplishing. I have had people say that they believe this is work that needs to be done.
FUTURE RECOMMENDATIONS OR NEW HYPOTHESES
Jirava says that after contemplating the project he can find nothing he would change.
“We had some crops that were large disappointments,” he says, “but I truly believe we learn more from our failures than we ever do if things work right the first time. Learning that alternative crops won’t grow is just as important to know as how to grow them.”
DISSEMINATION OF FINDINGS
About 30 people attended each of three field days in 1999, 2000 and 2001. In 2000, 15 academics from central Asia toured the project site. And the board of directors of the Pacific Northwest Direct Seed Association, along with a class of 20 graduate students from Washington State University, attended the 2001 tour.