Advancing Sustainable Agriculture in the Pacific Northwest

Conservation Tillage Systems

Information Resource

Pacific Northwest Conservation Tillage Handbook Series No. 23
Chapter 2 - Conservation Tillage Systems and Equipment, May 1999


Direct Seeding or No-Till....
What's the Difference?

Authors: Roger Veseth, WSU/UI Extension Conservation Tillage Specialist, Moscow, ID; and Russ Karow, OSU Extension Cereal Specialist, Corvallis, OR.

Direct seeding is becoming a commonly accepted term across the Northwest and around the world. The Northwest Direct Seed Cropping Systems Conferences in 1998 and 1999 each drew audiences of about 900 compared to 200-350 for similar NW no-till and conservation tillage conferences over the past 25 years. Is direct seeding that much different?

Well, yes and no. YES in that dramatic improvements in crop management and equipment technologies compared to 20-30 years ago and (here in the U.S.) new cropping flexibility under the USDA farm program can greatly increase the success of these planting systems today compared to some difficult times with "no-till" in the past. We also now have a much better understanding of soil quality and productivity benefits and potential for improving production efficiency than in the past. Soil erosion control is becoming an important side benefit of more productive, more profitable farming systems.

And now the NO part. It is largely semantics. Direct seeding is, for the most part, just a "new improved" term for no-till planting systems, but it does provide the opportunity for more accurate descriptions of the actual planting systems and seedbed conditions. Now let's get into the meat of the discussion.

Traditional Tillage Systems Terminology

Tillage system terminology can get confusing, but keep in mind that the end results - erosion control, soil quality and productivity, production efficiency and profitability - are the important factors. Don't get too side-tracked on terminology. The Conservation Technology Information Center coordinates annual national surveys of tillage practices across the U.S. and has defined several categories:

No-till - Soil is left undisturbed from harvest through planting except for strips up to 1/3 of the row width

Mulch-till - Full width tillage which disturbs all of the soil surface prior to or during planting and retains 30% or more surface residue cover

Conservation tillage - Umbrella term for the above tillage systems which maintain 30% or more residue cover

Reduced-till - Tillage systems that leave 15-30% residue cover

Intensive-till or conventional-till - Tillage systems that leave less than 15% residue cover

Tillage definitions help, but there are lots of "gray areas" when it comes to fitting the wide range of equipment options and final field conditions into these definitions. Although the term "no-till" has been used for more than three decades, there is still confusion about what planting systems are included or excluded. Some no-till drills are so low disturbance that it can difficult to see where they have seeded - examples of "true no-till or zero-till" systems. In contrast, some one-pass, "no-till" implements might be better described as a "till-plant" systems because they result in substantial soil disturbance and residue burial. What we have today are a wide range of high- to low-disturbance "no-till" systems, which may seem like somewhat of a contradiction of terms.

The term direct seeding has evolved, in part, to more effectively describe the planting process and end results, and this is one reason why it is becoming an increasingly common term worldwide. It tends to be a more flexible and inclusive term rather than exclusive, allowing more grower and industry innovation. This flexibility can help to overcome practical challenges in residue and pest management as we move towards the transition to low-disturbance direct seed / no-till - which offers the greatest long term potential benefits in erosion control, soil quality and productivity, water conservation, energy efficiency, and production efficiency. The "newer" term of direct seeding can also help get past the "baggage of past failures" associated with no-till, emphasizing that many advances in crop and pest management technologies, equipment, and products now make it a "new ball game." There are some variations of direct seed systems that do not fit in the traditional definition of no-till, and when they do not, those differences need to be described. So, direct seeding is not just a new name for the same old practice, but a new name to reflect new management technologies and systems that are now available and will continue to be improved.

Direct Seed Systems Definitions

As the name indicates, all direct seed systems have at least one important factor in common - that there is no traditional "full width" tillage for seedbed preparation with field cultivators, or other secondary tillage implements prior to planting. To most effectively describe the planting process and final seedbed conditions, direct seeding should be further categorized into high- to low-disturbance, and one- or two-pass systems. The following are descriptions of some common types or variations of direct seed systems today.

Low-Disturbance Direct Seeding

Narrow knives, single discs or double discs (standard or offset with one leading edge) only disturb a narrow strip of soil between openers retaining nearly all of the residue on the surface. This would be the same as the traditional "no-till, zero-till or slot-till" definitions.

High-Disturbance Direct Seeding

Hoe or sweep openers disturb more of the soil between openers, though usually not full-width, and still retaining much of the residue on top. With some flatter sweep blades, the surface soil and residue disturbance can be minimal even though much of the surface layer is undercut with the opener. Obviously, the furrow size, soil disturbance and residue retention will vary with opener designs, speed, soil moisture and other factors.

One-Pass or Two-Pass Direct Seed Systems

Growers can choose between one-pass direct fertilize and seed systems, and two-pass systems with direct fertilizing and direct seeding in separate operations. In both cases, there are no other tillage operations for seedbed preparation before seeding. The choice depends on the precipitation zone and seasonal distribution, length of planting windows, equipment availability and cost, crop choices, available labor, and a number of other consideration. There are a number of "direct-shank" fertilizer applicators for fertilizing without prior tillage. Some can be very low disturbance, such as narrow shanks or knives, coulter-knife combinations, coulter - pressure injection and spoke wheel applicators. In some lower and intermediate rainfall areas, direct fertilizer application in the fall before direct seeding spring crops is becoming increasingly common, helping to improve nitrogen availability to the crop in our dry PNW spring / summer environment. The one-pass and two-pass systems could result in similar soil and residue disturbance in the final seedbed if the similar fertilizer and seed openers are used in both systems. Two differences that could have agronomic effects would be that the one-pass system has 1) more precise positioning of the deep band fertilizer in relation to the seed row, and 2) may have soil disturbance from the fertilizer opener below the seed-row (depending on the fertilizer opener type and configuration), both of which can increase plant tolerance to root diseases in higher root disease situations (e.g. cereals after cereals).

Example Systems - To help others understand your direct seed system, you should use the above "descriptive categories" that best fit your system. Two examples are one-pass, high-disturbance direct seed systems, and two-pass, low disturbance direct fertilize and direct seed systems. You could also add other descriptors that help improve the understanding of your system, such as two-pass, low disturbance, fall direct fertilize - spring direct seed systems. These types of descriptions are definitely longer and more cumbersome than saying "no-till," but it makes for much better communications.

A Hybrid "Till-Direct Seed" Category

Fall Mulch-till - Spring Direct Seed (also know at the Stale Seedbed) - This is one type of "direct seeding" that does not fit the typical "no-till" definition because of full-width tillage between harvest and planting. In the world of tillage definitions, this is categorized as "Mulch-till." It needs to be pointed out that these fall mulch-till - spring direct seed systems will not achieve improvements in soil quality that are possible with direct seeding alone. However, it is a big step in the right direction. For some growers that struggle with heavier residue levels, wet cold spring conditions, or other production challenges in the higher rainfall, annual cropping regions, a combination of mulch-till in the fall and direct seeding of spring crops without spring tillage can provide an opportunity to begin the transition into lower disturbance direct seed systems for spring crops. As new crop rotation and residue management technologies become available to deal with the heavy crop residue, growers can begin to phase out the fall tillage component and move into continuous direct seed systems. Compared to mulch tillage systems with both fall and spring tillage before spring crops, this "hybrid" system offers the potential for significant improvements in residue retention for erosion control and water conservation and reduced soil compaction from spring tillage operations on wet soils. Obviously, there will also be some corresponding improvements in soil quality, but less than with direct seeding alone.

Can You Be a Partial Direct Seed Farmer???

Another yes and no answer. But, there are actually two questions to answer. First on a field basis and second on a farm basis.

No... on a Field Basis

Continuous direct seeding is the only way to reap the full soil improvement benefits from direct seeding. Using intensive tillage at any time in the rotation cycle disrupts the improvements in soil organic matter content, macroporosity and other soil productivity factors that take time to build and for you to see the benefits. HOWEVER, from a practical standpoint, if you don't have the equipment, crops diversity, residue management options, etc. needed for continuous direct seeding now, using mulch-tillage intermittently with direct seeding in your rotation is much better than continuous mulch-till or more intensive tillage.

Tillage results in increased soil oxygen levels and higher soil temperatures that stimulate intense microbial decomposition of soil organic matter and the resultant release of soil carbon as carbon dioxide. Soil organic matter is biologically burned off faster with intensive tillage than it can be built through the addition of new crop residues under our current dryland cropping systems with intensive tillage. Organic matter is a critically important soil component directly related to soil fertility, water holding capacity and infiltration, aggregation and structure, erodibility, biological activity and a long list of other soil properties affecting soil productivity and soil quality. Recent research shows that continuous direct seeding systems offer the greatest potential for increasing soil organic matter content over time.... now commonly termed "carbon sequestration" under the topic of global warming. The less severe and less frequent the soil disturbance, the greater the carbon accumulation potential.

In addition to organic matter, another important related soil quality benefit of continuous direct seeding is the improved soil macroporosity. That refers to the proportion of larger soil pore spaces for water and air movement created by undisturbed root channels, earthworm holes and other soil fauna. Full-width tillage breaks the continuity of these soil pores and eliminates or greatly reduces their effectiveness. In a long-term tillage near Pendleton, OR, researchers found that rates of water infiltration (inches/hour) into the soil were 0.04 in the plow-conventional tillage treatment, 1.1 after the first year of direct seeding, and 5.1 after 16 years of direct seeding. That's a pretty dramatic difference in the potential for water runoff and evaporation, and storage for crop use. Part of this improved soil structure is also attributed to increased microbial activity associated with higher organic matter content and increased soil water near the surface without tillage - increasing soil aggregation and "tilth," as well as fertility.

Yes.... on a Farm Wide Basis

Being a direct seed farmer does not mean you need to direct seed your entire farm from the start. Successful direct seeding and more intensive cropping takes time to gain the knowledge and experience to develop management systems that are best adapted to your farming conditions. We would encourage you start on a few fields rather than the whole farm and gradually increase the acreage with increased confidence. Realize that you will probably have to learn from your mistakes, or at least learn what works and what doesn't on your fields. Remember that equipment and crop performance will likely change with improvements in soil quality over successive years in the transition to direct seeding

If you can afford to keep a set of your current tillage and planting equipment as well as a direct seeding drill, or rent a drill from a neighbor, local dealer or conservation district, then it makes sense to utilize both systems while you are working your way through the learning curve and transition to direct seeding. This is especially true given current economic conditions and the ever changing weather.

Think of Your Fields like a Financial Investment Systems - You can keep some of your fields in "certificates of deposit - CDs" under your current, generally-reliable tillage / rotation system where you get a known rate of return. Put some of your field in higher-yielding "bonds" while you explore new cropping systems using direct seeding where you know it will work in the rotation, but still have the option of mulch-till where needed in the rotation as well. A new cropping example for the crop-fallow region could be flex-cropping, or recropping part of your winter wheat stubble acreage in the spring by direct seeding spring crops when there is adequate soil moisture, markets, and weed levels permit, but fallowing if spring planting is not feasible. Similarly, you could also direct seed winter wheat following spring crops on part of your farm when there are early fall rains and other economic and agronomic factors were favorable. You would need to be prepared both mentally and financially to not plant some fields in the spring or fall when it will not make sense to do so. And finally, put some of your field in the "stock market" - continuous direct seeding using more diverse and intensive rotations to make it work - where you have potential for the greatest long term and short term gains, but where you are also at a higher level of risk early on the learning curve. As you gain experience, you can add more fields into this investment area with the greatest potential. Fortunately, unlike in the stock market, your risk level will continue to decline with additional years of experience with direct seeding and more intensive cropping, and with continued advances in production technologies. The weather is obviously always an unpredictable factor to keep in mind.

Define YOUR Direct Seed Systems

Direct seeded acreage and the number of growers working in direct seed systems is rapidly increasing worldwide. It is important to continually explore new research technologies and learn from experiences of other direct seed growers because these are rapidly evolving farming system. Direct seeding and flexible intensive cropping will require more information on a field-by field basis and greater communication with input providers and landowners to be successful. You will need to decide what crops to plant in which fields based on markets, field history, field moisture status, weed and disease problems, and how to manage those problems under direct seeding.

Every grower has different production conditions and different experiences with direct seeding, and everyone can benefit from sharing these experiences. One key to effective sharing will be more accurate descriptions of the direct seed systems being used. The same is true for researchers, who need to give detailed descriptions of the treatments and production conditions with the research results so that others can more easily adapt the results to different farming conditions and different equipment. Fertilizer placement, seed and fertilizer opener types, row spacing, packer type, crop rotations, residue amounts and management, growing conditions and many other factors can effect the performance of a direct seed system and need to be carefully defined for the benefit of others. Everyone will benefit from improved descriptions of direct seed cropping systems.

 


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.

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 1999, 47 new PNW Conservation Tillage Handbook Series have been added to the original 98. Copies of the complete Handbook 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 Internet home page (http://pnwsteep.wsu.edu) Pacific Northwest STEEP III Conservation Tillage Systems Information Source. The home page 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).

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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