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Tillage terminology

What we can learn

If someone should tell you no-till isn't really no-tillage (or no soil disturbance), tell them they're absolutely right. In the U.S., the term "no-till" merely identifies the one system designed to produce crops with the least amount of tillage. You're still making a small groove or slit in the soil to plant the seed. However, the term no-till is so easy to remember and say that it is often used in place of conservation tillage in casual discussion. Canadian farmers avoid the no-till misnomer. They use the term "direct-seeding." Perhaps farmers in the Midwest have hit upon a true form of no-till. During severely wet planting seasons, some will hire pilots to drop soybeans from airplanes onto cropland. That, they say, is "true no-till!" On the serious side While this may seem a bit frivolous, it does point to a more serious side of this broad range of systems we call "conservation tillage." While the goal for each is to leave 30 percent or more crop residue after planting, the flexibility to "till a little more or make another pass," is always the producer's prerogative, more so with some conservation tillage systems than others. For instance, both mulch-till and strip-till systems allow for more flexibility in tillage, which can make it easier to fall short of higher residue goals. The example on page 12 can help you get a better idea of the factors involved in trying to meet specific residue goals.

Table 4. Tillage terms and definitions Tillage Systems Definitions As featured in the annual National Crop Residue Management Survey Conservation Tillage (30 percent or more* crop residue left after planting) Any tillage and planting system that covers 30 percent or more of the soil surface with crop residue, after planting, to reduce soil erosion by water. Where soil erosion by wind is the primary concern, any system that maintains at least 1,000 pounds per acre of flat, small grain residue equivalent on the surface throughout the critical wind erosion period. No-till - The soil is left undisturbed from harvest to planting except for nutrient injection. Planting or drilling is accomplished in a narrow seedbed or slot created by coulters, row cleaners, disk openers, in-row chisels or roto-tillers. Weed control is accomplished primarily with herbicides. Cultivation may be used for emergency weed control. Ridge-till - The soil is left undisturbed from harvest to planting except for nutrient injection. Planting is completed in a seedbed prepared on ridges with sweeps, disk openers, coulters, or row cleaners. Residue is left on the surface between ridges. Weed control is accomplished with herbicides and/or cultivation. Ridges are rebuilt during cultivation. Mulch-till - The soil is disturbed prior to planting. Tillage tools such as chisels, field cultivators, disks, sweeps or blades are used. Weed control is accomplished with herbicides and/or cultivation. (Zone-till and Strip-till - Although these are popular terms in some areas, they are not official survey categories because they are considered modifications of no-till, mulch-till or "other tillage types.") Other Tillage Types: (less than 30 percent crop residue left after planting) Tillage and planting systems that may meet erosion control goals with or without other supporting conservation practices (i.e. strip cropping, contouring, terracing, etc.). Reduced-till - Tillage types that leave 15-30 percent residue cover after planting or 500 to 1,000 pounds per acre of small grain residue equivalent throughout the critical wind erosion period. Conventional-till (intensive tillage) - Tillage types that leave less than 15 percent residue cover after planting, or less than 500 pounds per acre of small grain residue equivalent throughout the critical wind erosion period. Generally involves plowing or intensive tillage. *The emphasis on the "30% or more" should often be placed on the "more." Considerably more than 30% cover could be necessary to achieve soil erosion tolerance levels ('T') and related production and environmental benefits.

Tillage definitions Each year, the Conservation Technology Information Center (CTIC) compiles a national survey of tillage practices by crops and acres planted. Data for the survey are gathered by USDA Natural Resources Conservation Service field offices, soil and water conservation districts, and others. The definitions used to gather the information are listed in table 4. Year after year, these definitions assist in compiling comparable data to track national tillage trends (to the county level)

Remember: Definitions aren't as important as achieving the desired results. Survey data are widely used by the agricultural industry to develop farmer education programs, target product marketing, and guide research and development efforts. At the very least, these definitions could foster some interesting discussion at your next conservation tillage club meeting.