Advancing Sustainable Agriculture in the Pacific Northwest

Conservation Tillage Systems

Information Resource

Chapter 2- Systems and Equipment, No. 12, Fall 1988

Conservation Tillage Considerations for Cereals

Roger Veseth

The use of conservation tillage systems, such as reduced tillage and no-till, for cereal production has sharply increased in the Northwest in recent years. About 36 percent of the 1987 cereal acreage in Idaho, Oregon and Washington was under some type of conservation tillage, up from 24 percent in 1982. This trend toward increased use of conservation tillage is expected to accelerate in the 1990's. A major reason for this increase is that producers are realizing the potential advantages of conservation tillage and the importance of keeping up to date on new technology to develop and maintain successful systems.

The USDA Farm Program provides added incentive for producers to explore conservation tillage systems if they have not already discovered the potential advantages. The Conservation Compliance provisions of the 1985 Food Security Act require producers to have a conservation plan approved on their highly erodible cropland by 1990 and fully implemented by 1995 in order to remain eligible for USDA program benefits. Although conservation tillage is not necessarily a requirement in conservation plans, it is one of the most effective practices for holding topsoil in place and one of the few conservation options which can also help improve production efficiency.

A substantial part of the new technology for conservation tillage systems in the Northwest has been developed through the STEEP (Solutions To Environmental and Economic Problems) research program. Over 100 scientists from the universities and USDA-Agricultural Research Service in Idaho, Oregon and Washington have been involved in this cooperative, federal-state research effort since 1975. STEEP and related research efforts have accelerated the development of new technology for more efficient farming systems which effectively conserve soil and water resources.

Why Consider Conservation Tillage?

Potential Advantages

There are numerous potential advantages of conservation tillage:

  1. Improved Production Efficiency - The potential for reducing production costs is one of the most commonly reported reasons producers give for changing from conventional to conservation tillage. Reducing the number of trips over the field saves fuel, time, labor costs, and machinery wear and maintenance.
  2. More Timely Planting - For both winter and spring cereals, yield potentials typically decline as planting dates are delayed past "optimum seeding windows" for each particular area. With fewer tillage operations, more timely planting is often possible with conservation tillage, providing for a potential increase in yield. However, in areas where wet soils are a problem in the spring, more surface residue may delay soil drying and potentially cause delays in spring seeding.
  3. Increased Soil Water Storage - A higher yield potential, as the result of increased soil water storage, is an important advantage in lower and intermediate precipitation areas. STEEP research has demonstrated that surface residue commonly increases overwinter soil water storage about 20 percent through reduced runoff and evaporation compared to low-residue conventional tillage. Each additional inch of available water increases wheat yield potential by 5 to 7 bushels. Consequently, where 10 inches of precipitation occurs overwinter, a 2-inch increase in soil water storage could increase yield potential roughly 10 to 14 bushels if water is the major yield-limiting factor.
  4. Soil Productivity and Water Quality Maintained -One of the most obvious advantages ii maintaining soil productivity by effectively reducing erosion. STEEP research points out that present-day yields would often be 25 to 50 percent higher on many areas of eroded cropland in the Northwest if erosion had been controlled. The research also demonstrates that maintaining more crop residue on the surface with conservation tillage can reduce soil erosion by 90 percent or more depending on the surface residue level, soil roughness and other factors. When soil erosion and surface runoff are effectively controlled, the potential for surface water pollution is also greatly reduced. Pacific Northwest Extension Bulletin PNW 275, Effective Conservation Farming Systems, describes the runoff and erosion control potential of several conservation tillage systems.

Potential Disadvantages

Conservation tillage also has potential disadvantages. Because of the extreme variations in Northwest cropping regions and individual grower equipment and management, the obstacles to developing successful conservation tillage systems will vary greatly. There are, however, some disadvantages which are commonly encountered.

  1. More Complicated Management - One of the biggest disadvantages of conservation farming systems is that they are often more complicated than intensive tillage systems. In order to take advantage of lower production costs and/or improved production efficiency, producers must make a special effort to search for the information they need to put together a successful crop management system. This can be a big obstacle for growers who are new to conservation tillage and are not sure where to find needed information. Growers also need to make a commitment to keep up to date on new developments in technology.
  2. Potential Additional Equipment Expense - Additional equipment expense is possible, but often not necessary. Some conservation farmers have made significant financial investment in equipment modification or purchase, while others have only made adjustments in how they use their present conventional equipment. Minor modifications or attachments for combines are usually desirable to eliminate straw and chaff rows.
  3. USDA Commodity Program a Greater Obstacle -Crop rotation is often more important for controlling some diseases and weeds in conservation tillage than in conventional tillage. Consequently, USDA commodity acreage-restriction programs may be more of an obstacle for conservation farmers than for conventional tillage farmers in some areas because of the constraints they place on flexibility in crop rotation. For example, the inclusion of a spring barley crop to lengthen 2-year rotations, such as wheat-pea or wheat-fallow, to 3-year rotations can be restricted by lack of sufficient barley base-acreage and the potential loss of wheat base.
  4. Greater initial Risk - Trying anything new for the first time creates uncertainty. When growers make a major change in management practices, there can be an initial risk that yields may not be maintained because of unforeseen problems. As they gain experience and confidence with conservation tillage practices on their own farm over time, the risk level declines. Bankers and lending agencies can have a high level of risk aversion, thus limiting the flexibility and options of producers wishing to explore conservation tillage.

Some Key Crop Management Considerations

Knowledge of Pests

The first step in controlling weed, disease and insect problems is to develop a basic understanding of each major crop pest you encounter in your area. What is its life cycle? What conditions affect its survival from year to year? What are its "weak links" that can be capitalized upon for control through -op management options? This does not mean that producers will need university degrees in plant pathology, entomology and weed science, but it may mean reading some Extension publications or possibly attending some conferences that address pest problems in their area. If producers do not have a good understanding of the pests they are dealing with, they will probably have a more difficult time developing successful conservation tillage systems,

Crop Rotation

In conventional tillage systems, intensive tillage has served as a substitute for other pest management choices, one of the most significant being crop rotation, Crop rotation is probably the single most effective pest management tool in conservation tillage. It is particularly important in reducing the potential for many soilborne diseases of cereals, as well as other crops. For example, crop rotations with 2 years out of winter cereals can effectively control Cephalosporium stripe in winter wheat under conservation tillage. One non-cereal crop in the rotation controls take-all for the following wheat crop and also helps reduce the incidence of Rhizoctonia root rot and Pythium root rot in cereals.

Crop rotation is important in weed control as well. For example, control of winter-annual grass weeds, such as downy brome (cheatgrass) or jointed goatgrass, is greatly improved by including spring crops in the rotation, or crops which allow use of grass weed herbicides not possible under winter cereals.

Combine Residue Distribution

Producers successfully using conservation tillage often list uniform residue distribution from the combine as one of the first important steps. Impacts of straw and chaff rows include: drill plugging; poor seed-soil contact; straw contact with the seed, nutrient tie-up; increased soilborne disease; a concentration of volunteer and weed seeds, resulting in more crop competition; reduced herbicide effectiveness; and increased rodent damage. Commercial straw and chaff spreaders, now available for most combine models, and farmer shop modifications are often very effective in eliminating straw and chaff row problems. Pacific Northwest Extension Bulletin PNW 297, Uniform Combine Residue Distribution, provides more information on this topic.

Fertilizer Application

STEEP research has shown that early root access to fertilizer banded below the seeding depth and near the seed row often provides more efficient fertilizer use and increased cereal yield, particularly under conservation tillage. The advantage of placement can be enhanced or overshadowed, however, by other factors which influence plant nutrient uptake. These factors include: soil nutrient level, nutrient mobility, precipitation level and distribution, soil pH and soil temperature. The greatest response to fertilizer banding is on soils with low soil-test nutrient levels and under cold wet conditions. A review of fertilizer placement considerations for cereal root access in no-till and minimum tillage is available in Pacific Northwest Extension Bulletin PNW 283, Fertilizer Band Location for Cereal Root Access in Conservation Tillage.

Seeding Considerations

Using good quality seed of adapted cereal varieties is as important under conservation tillage as in conventional tillage. Seeding date and rate can also be important management choices. Seeding date can significantly influence the potential impacts of several important pests under conservation tillage. For example, late fall seeding greatly increases the potential for damage from Pythium root rot, whereas early seeding can increase the potential for Cephalosporium stripe and strawbreaker foot rot. Integrated management strategies have been developed through the STEEP research effort to effectively reduce the potential of many of the plant diseases encountered, Seeding date can also influence weed control options and weed potential, particularly with winter annual grass weeds, depending on fall weather conditions, herbicide options and other factors.

Seed age can bean additional consideration with seeding date. STEEP research has shown that in areas with potential for Pythiwn root rot, using current-year winter wheat seed will reduce the potential for damage with late seeding dates compared to older seed lots, Under normal or earlier seeding times, seed age generally did not result in differences in Pythium root rot because the pathogen is less active when soils are warmer and dryer, In addition, current-year seed can result in more high-temperature dormancy problems than older seed with early or normal winter wheat seeding dates in fallow. The importance of seed age is greatly influenced by storage conditions.

Seeding rates slightly higher than normal (10 to 25 percent) have commonly been used in conservation tillage to compensate for less favorable seedbed conditions. The need for increased seeding rates must be evaluated, however, for the particular field conditions including: previous crop, available water; tillage and planting equipment used; final seedbed conditions; tillering ability of the cereal variety; and other factors.

Herbicide Options

Herbicide options after the crop has emerged are generally the same under conservation tillage as under conventional tillage, Some preplant and pre-emergence herbicides which require thorough soil incorporation will, however, have limited use in conservation tillage. Where these herbicides cannot be used, other herbicide and management options will need to be selected for control of the particular weeds. It is always important for application equipment to be properly adjusted to effectively penetrate the crop stubble and to ensure weed contact with foliar-active herbicides.

Tillage System and Equipment Selection

The type of equipment producers select for their conservation tillage system will depend on the individual farming situation. Two important considerations in conservation tillage are seeding through the surface residue and applying fertilizer to achieve the highest use efficiency. A majority of the commercial conservation tillage drills now available have improved residue handling potential and fertilizer placement options. Producers are also modifying their drills with numerous commercial attachments and shop fabrications. Many producers have adapted their own chisels and cultivators for banding fertilizer in order to reduce the number of field operations.

Equipment purchases or extensive modifications are often not needed for effective conservation tillage. A common alternative approach is changing how conventional equipment is used in order to maintain more surface residue. Reductions in tillage speed and depth, turning the plow furrow uphill, removing trash boards on moldboard plows, and other adjustments in equipment use can significantly increase surface residue retention.

Some fertilizer dealers in the Inland Northwest, such as McGregor and Wilbur-Ellis, now have fertilizer injector equipment for direct shanking of fertilizer without prior tillage in ''shank and seed" type systems. Consequently, producers can now use their standard drills and avoid equipment purchases or modifications for fertilizer placement under conservation tillage.

There is no one best tillage system or equipment combination for all situations. Climatic conditions, available equipment, crop rotation options, soil type, topography, cash flow, information resources and many other factors influence producer choices.

Information Resources For Getting Started

Successful conservation tillage requires much more than just fewer tillage operations, equipment purchases or modifications, or maintaining more surface residue, It must bean integrated system of crop management choices affecting crop health and production efficiency.

A big investment you have to make in the transition to conservation tillage is your time spent pulling together the information you need to understand and implement a system. Talk with conservation tillage farmers in your area. Attend educational conferences such as the Eighth Annual Inland Empire Conservation Farming Conference at the Washington State University Coliseum in Pullman, Feb. 7, 1989, Contact your local Conservation District, USDA-SCS Office and Extension Agricultural Agent for information.

Reference materials are also available through the STEEP Extension program, which is designed to help increase producers' access to new technology developed through STEEP and related conservation farming research efforts. The quarterly STEEP Extension Conservation Farming Update provides in-depth reviews of the latest developments in conservation tillage research in the Northwest, written from a management perspective.

A major focus of the STEEP Extension program is currently on an early 1989 release of a new Pacific Northwest Extension Conservation Farming Handbook. This Handbook will be one of the most comprehensive reference guides on conservation tillage for this region. It will contain more than 110 articles and Extension publications on the latest research developments in all aspects of conservation tillage management. It will continue to be updated in the future. To get on the mailing list for the Update and to be informed when the Handbook is available, contact: Roger Veseth, WSU/UI Extension Conservation Tillage Specialist, Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow ID 83843 (208) 885-6386, or Don Wysocki, OSU Extension Soil Specialist, Columbia Basin Agricultural Research Center, Box 370, Pendleton, OR 97801 (503) 276-5721.

Developing a conservation tillage system is a big commitment, requiring a dedicated effort. But, the rewards of improved production efficiency and resource conservation are well worth the investment.

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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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