Part 1, Section 1: Soil Management
- Primary tillage: deep tillage operation (>6") that loosens and fractures soil to kill weeds, reduce soil strength, mix residue, lime, fertilizers and manure into soil.
- Secondary tillage: shallow tillage operation (<6") to kill weeds, cut and cover residues, incorporate herbicides, prepare a pulverized seedbed.
- Tertiary tillage: in crop tillage used to control weeds or inject fertilizers and manure.
|Source: National Crop Residue Management Survey, Conservation Tillage Information Center.|
|Conventional tillage||Tillage systems that leave less than 15% residue cover at planting, or less than 500 lbs/A small grain residue equivalent throughout critical erosion period.|
|Reduced till||Tillage systems that leave 15 to 30% residue cover at planting or 500 to 1000 lbs/A small grain residue equivalent throughout critical erosion period.|
|Mulch till||Full-width tillage system that disturbs the whole soil surface prior to and/or during planting. Leaves more than 30% residue cover at planting or more than 1,000 lbs/A or small grain residue throughout critical erosion period.|
|Ridge till||The soil is left undisturbed from harvest to planting except for strips up to one-third of the row width. Planting is completed on the ridge and usually involves the removal of the top of the ridge. Residue is left on the surface between the ridges. Ridges are rebuilt during cultivation. Ridge till is sometimes referred to as plant-till.|
|No-till and Strip-till||The soil is left undisturbed from harvest to planting except for strips up to one-third of the row width. Cultivation may be used for emergency weed control. No-till is sometimes referred to as direct seeding, slot planting, zero-till, row-till, and slot-till.|
- Tillage classifications based on residue cover (Box 1.1-2)
- Used by the Conservation Technology Information Center in West Lafayette, IN, http://www.conservationinformation.org. Tillage that leaves more than 30 percent residue cover after planting is conservation tillage, while tillage that leaves less than 30 percent residue cover after planting is not conservation tillage.
- Intensive Till or Conventional Till (less than 15 percent residue cover after planting)
- Involves full-width tillage and may involve one, three or perhaps up to 15 tillage passes. There is less than 15 percent residue on the soil surface after planting. Moldboard plowing and/or multiple tillage trips are involved.
- Reduced Till (15 to 30 percent residue cover after planting)
- Somewhat similar to mulch till in that they involve full-width tillage, use the same implements and may use one to three tillage trips. Reduced-till, however, leaves 15–30 percent residue on the soil surface after planting.
- Mulch Till (more than 30 percent residue cover after planting)
- Fullwidth (100 percent of soil surface disturbed) tillage system that usually involves one to three tillage passes. Implements such as chisel plows, disks, field cultivators and combination tools are used.
- Ridge Till
- Involves building 4- to 6-inch high ridges during row cultivation and scraping off 1 to 2 inches of the ridge during planting.
- No Till
- Concept has evolved as technology has changed. With no-till, producers disturb only the minimal amount of soil needed to ensure a good stand and yield.
Variations under the No-Till Umbrella
Midwest United States
- Strip-till: usually involves a mole knife to till a zone approximately 10 inches wide and 4 to 5 inches high in the fall. Some combination of nutrients is usually applied at the same time. The following spring, planting occurs in the tilled strip.
Southeast United States
- Strip-till: used on the Sandy Coastal Plain soils (soils that naturally compact) in the Southeast portion of the United States. A ripper runs about 14 inches deep ahead of or with the planter.
- Vertical tillage: used with a narrow ripper about 12 to 14 inches deep, usually in the fall, which causes very little surface soil disturbance. Planting occurs directly over the tilled strip.
- Fluffing harrows: used to “fluff” the residue, allowing excess moisture in the seedbed to evaporate and improve planting conditions.