Advancing Sustainable Agriculture in the Pacific Northwest

Conservation Tillage Systems

Information Resource

PNW Conservation Tillage Handbook Series
Chapter 2 - Conservation Tillage Systems and Equipment, No. 21, May 1997


CRP Take-Out: A Unique Opportunity for the Transition to Direct Seeding

Authors: Roger Veseth, WSU/UI Conservation Tillage Specialist, Moscow, ID; Baird Miller, WSU Dryland Cropping Systems Agronomist, Pullman; Tim Fiez, WSU Soil Fertility Specialist, Pullman

About 80% of the contracts on 2.5 million acres of Northwest cropland in the Conservation Reserve Program (CRP) are scheduled to expire in 1997. Although growers have offered much of this CRP acreage for enrollment in the 1997 CRP sign-up, a considerable amount of the acreage may not be accepted for new contracts in the national selection process. If CRP land is returned to crop production, growers should take advantage of this unique opportunity to make the transition to direct seeding or other minimum tillage systems. These systems can provide effective soil erosion control and water conservation, maintain soil quality improvements gained over 10 years in grass, and the bottom line....improve profitability and competitiveness in the global market.

CRP May Eliminate the Direct Seeding "Transition Period"

There can often be a 3- to 5-year "transition period" during the change from intensive tillage systems to no-till direct seeding systems before soils begin to reach a new equilibrium in physical, biological and chemical processes and properties. Early in this transition period, crop yields can sometimes be similar to or lower than yields under intensive tillage. However, as the transition period progresses, growers and researchers across the Northwest and around the world have noted higher crop yields compared to intensive tillage. The increased yields are attributed to improvements in soil organic matter content, soil structure or "tilth," soil biological activity, and water infiltration, and a reduction in weeds and diseases with adequate crop rotations.

Improvements in soil quality during CRP may help growers eliminate or shorten this typical transition period, and achieve enhanced yield potentials with direct seeding of CRP fields sooner than if converting cropland from intensive tillage to direct seeding. If growers have been considering direct seeding, CRP take-out is the time to start.

Northwest CRP Take-Out Research Effort

The results of a 3-year research project on CRP take-out for crop production in Washington State illustrate that direct seeding can provide similar economic returns to intensive tillage systems with other significant benefits to the environment and soil quality. The research effort included 10 large-scale, field research trials on crested wheatgrass CRP land in the low rainfall, crop-fallow regions, where the vast majority of CRP is in the State. Field trials were conducted in 7 counties in cooperation with 15 growers, 12 researchers and more than 25 other Ag support personnel. A variety of tillage and residue management systems were evaluated in three trials on CRP take-out with tillage for summer fallow - winter wheat, and seven trials on spring CRP take-out with direct seeding and/or tillage for spring crops. Some of the management options included: fall versus spring take-out; residue management practices such as flailing, harrowing, and burning; a range of tillage intensities, and direct seeding systems. This field research project used the large-scale, replicated, on-farm testing approach with farm-scale equipment operated by the growers.

The research was supported in part by two USDA-Cooperative Research, Extension and Education Service (CSREES) grant projects through Washington State University: 1) PNW STEEP II (Solutions To Environmental and Economic Problems) research and education program on conservation farming technologies; 2) Northwest Columbia Plateau Wind Erosion - Air Quality Project.

Results Highlight Direct Seed and Minimum Tillage Benefits

Intensive Fall Tillage Reduces Overwinter Water Storage

Fall discing reduced overwinter water storage by approximately 2 inches compared to leaving the grass undisturbed over winter because of increased evaporation. By winter wheat planting after fallow in the trials near Connell and Lind, available water storage in the fall disc system was still about 1 inch less than in take-out systems with no fall tillage. This water loss resulted in lower plant stands and a 3-5 bu/A yield reduction and lower profitability compared to spring take-out systems. Although fall versus spring CRP take-out trials were not conducted for spring cereals, yield reductions in spring wheat from water loss by intensive fall tillage could be 10 to 14 bu/A based on the 2-inch overwinter water loss in other trials.

Residue Management and Tillage Summary for Fallow

Burning -- The low to moderate surface residue levels with crested wheatgrass (generally 3,000-6,000 lbs/A) do not warrant the use of burning to achieve manageable residue levels at seeding time after fallow. Compared to other spring treatments, spring burning in the Franklin and Lincoln County sites did not result in significant differences in plant stand, yield, test weight, protein or net returns, and did not retain adequate surface residue for water conservation and erosion control.

Flailing -- Fall or spring flailing did not significantly affect surface residue cover or roughness after winter wheat seeding, improve plant stands or grain yield compared to other spring take-out treatments. Consequently, the additional cost of flailing was generally not recovered.

Harrowing -- Fall 2X harrowing - spring disc did not affect plant stands, surface residue and roughness after seeding, grain yield or net returns compared to two spring discings. It did, however, result in a slight reduction in downy brome population in the winter wheat crop due to increased weed seed germination before summer fallow establishment.

Maintaining Effective Erosion Protection -- All tillage and residue management combinations used in the three CRP take-out research trials for summer fallow-winter wheat were overly intensive, resulting in low surface residue levels that limited erosion protection and water conservation. All the systems included 2-4 rod weedings after primary tillage operations of discs, chisels or sweeps. The combination of fall harrowing and fall or spring undercutter or sweep would provide one of the most profitable and effective minimum tillage take-out systems for fallow. An application of Roundup RT before spring tillage on take-out trials for fallow helped reduce grass reestablishment, particularly under wet spring conditions. Chemical fallow and no-till seeding of winter wheat was not evaluated but may be an option in higher precipitation areas and years.

Direct Seeding Spring Cereals in CRP Take-out

Spray Rate and Timing for CRP Kill Before Direct Seeding -- Based on the results of cooperative small-plot research trials by Monsanto and The McGregor Co., a 48 oz/A rate of Roundup RT is generally recommended for a high percentage (90%+) kill of the crested wheatgrass for direct seeding systems without tillage. Application should be at least 21 days before direct spring seeding to reduce the potential for a "green bridge" of Rhizoctonia root rot and other root diseases that can be transferred from grass roots to the seeded crop. Because of crested wheatgrass dormancy in the fall, Roundup RT applications in the fall did not kill crested wheatgrass even with good fall regrowth and weather conditions.

Flailing Before Direct Seeding in Spring CRP Take-out -- Spring flailing ahead of direct-seeded spring wheat in 1996 spring CRP take-out trials near Ritzville and Waterville did not affect plant stands, root disease level or yield, and consequently was less profitable than direct seeding without flailing. Fall harrowing when grass residue was dry could provide a more cost effective alternative for spring crops after CRP. Under higher levels of grass residue, flailing of dry grass may provide a greater benefit for equipment operations and crop establishment.

Spring Burning Before CRP Take-out for Spring Crops -- In a direct-seeded spring wheat trial on crested wheatgrass near Ritzville, yields with burn - direct seed averaged about 3 bu/A higher than direct seeding into standing grass and about 3 bu/A lower than with a tillage comparison of disc - coil pack - fertilize and seed with conventional double disc drill. However, economic returns were not significantly different between the three systems.

Direct Seeding Versus Tillage Take-Out --Three spring take-out trials with direct-seeded hard red spring wheat were conducted in crested wheatgrass CRP in 11-inch rainfall areas in 1996: two trials near Ritzville and one near Waterville. Each trial compared several direct seeding systems with a reduced or conventional tillage system for comparison. Non-cereal crops were not evaluated in direct seeding for CRP take-out in the large-scale research trials, but could provide the advantage of being less susceptible to some of the root diseases and other pests encountered with cereals, which have more pests in common with CRP grass.

Yields of spring wheat in direct seeding systems were equal to or a few bushels per acre lower than yields of the tillage comparison systems. However, there were generally no significant differences in profitability. Higher grass survival was believed to be one of the main reasons for the small yield reductions in direct seed systems in some of the trials. The incidence of Rhizoctonia root rot was relatively high on the roots of both direct seeding and tillage take-out systems. Options to reduce grass survival and root disease potential could include spraying out the CRP grass the summer before spring planting or using non-inversion tillage, such as an undercutter or sweep, in the fall or spring before direct spring seeding. Harrowing when the grass residue is dry and brittle in the late summer or fall could provide an economical and effective residue management practice for spring seeding. Compared to intensive tillage, improved water conservation with direct seeding would increase yield potential if the crop can effectively utilize the increased available water.

In addition to effective, early grass kill, an important factor in the success of direct seeding CRP would be the drill capability to effectively penetrate the grass residue and soil for good seed-to-soil contact and accurate seed placement. Deep banding of fertilizer below seeding depth near the seed row would also help reduce the impacts of root diseases and increase yield potential.

Collaborative research under the direction of Ann Kennedy, USDA-ARS Soil Microbiologist in Pullman, WA, showed that direct-seeded CRP maintained soil quality parameters at a level more similar to CRP than did intensive tillage take-out. The amount of soil carbon (measured as readily mineralizable carbon) available for microbial growth was greater after direct seeding than after intensive tillage. Other national research shows that direct seeding can significantly build soil organic matter levels over time while tillage results in an increased loss of soil carbon as carbon dioxide released to the air by dramatically accelerating the rate of biological decomposition of plant residue and organic matter in the soil.

Copies of the CRP Take-out Research Summary

Detailed results from the 3-year CRP take-out research project are summarized in the November 1996 PNW Conservation Tillage Handbook Series No. 16 in Chapter 2, titled "Returning CRP to Crop Production -- A Summary of 1994-96 Research Trials in Washington State." Copies are available from the WSU Crop and Soil Sciences Dept. Cooperative Extension Office, P.O. Box 646420, WSU, Pullman, 99164-6420, phone 509-335-2915 or e-mail (ce6025@coopext.cahe.wsu.edu). This Handbook Series publication on CRP take-out, and eventually all the PNW Conservation Tillage Handbook, can also be accessed on the World Wide Web Home Page (http://pnwsteep.wsu.edu) titled Pacific Northwest STEEP III Conservation Farming Systems Information Source. For more information, contact Roger Veseth, WSU/UI Conservation Tillage Specialist, at 208-885-6386 or e-mail (rveseth@uidaho.edu).

The Pacific Northwest Conservation Tillage Handbook is a large three-ring binder handbook that is updated with new and revised Handbook Series publications. It was initiated in 1989 as a PNW Extension publication in Idaho, Oregon and Washington. Updates to the Handbook are provided when the updating card is returned. By 1997, 34 new PNW Conservation Tillage Handbook Series have been added to the original 98 publications Copies are available for $20 through county extension offices in the Northwest or ordered directly by calling state extension publication offices: Idaho -- (208) 885-7982; Oregon -- (541)-737-2513; Washington -- (509) 335-2999 (some shipping and handling charges and sales tax may apply).

It’s now accessible on the Internet! All of the PNW Conservation Tillage Handbook and Handbook Series are being put on the World Wide Web Home Page (http://pnwsteep.wsu.edu) titled Pacific Northwest STEEP III Conservation Farming Systems Information Source. The Web site also contains recent issues of the PNW STEEP III Extension Conservation Tillage Update, listings of other conservation tillage information resources, coming events and much more. For more information on the Handbook or updates to the Handbook, contact Roger Veseth, WSU/UI Conservation Tillage Specialist, Plant Soil and Entomological Sciences Department, University of Idaho, Moscow, ID 83844-2339, phone 208-885-6386, FAX 208-885-7760, e-mail (rveseth@uidaho.edu).

Pacific Northwest Conservation Tillage Handbook Series publications are jointly produced by University of Idaho Cooperative Extension System, Oregon State University Extension Service and Washington State University Cooperative Extension. Similar crops, climate, and topography create a natural geographic unit that crosses state lines in this region. Joint writing, editing, and production prevent duplication of effort, broaden the availability of faculty, and substantially reduce costs for the participating states.

For herbicide application recommendations, refer to product labels and the Pacific Northwest Weed Control Handbook, an annually revised extension publication available from the extension offices of the University of Idaho, Oregon State University and Washington State University. To simplify information, chemical and equipment trade names have been used. Neither endorsement of named products is intended, nor criticism implied of similar products not mentioned.

Cooperative Extension programs and policies comply with federal and state laws and regulations on nondiscrimination regarding race, color, gender, national origin, religion, age, disability, and sexual orientation. The University of Idaho Cooperative Extension System, Oregon State University Extension Service and Washington State University Cooperative Extension are Equal Opportunity Employers.

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Hans Kok, WSU/UI Extension Conservation Tillage Specialist, UI Ag Science 231, PO Box 442339, Moscow, ID 83844 USA (208)885-5971
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