Tillage Systems

  • Tilling the soil can help prepare a seedbed, kill weeds and disrupt dormant insects and plant pathogens, incorporate nutrients, and manage crop residues.
  • The yield benefits of a tillage system are specific to each individual field and production practices.
  • Each tillage system has advantages and disadvantages that need to be assessed for each field situation.

Tillage Comparisons

Farmers and agronomists have debated the pros and cons of no-till versus other tillage systems for decades. Reviews of research comparing corn and soybean yields between no-till and other tillage systems continue to find only small differences in yield.1 No-till corn and soybeans tend to perform better in southern and western regions over other tillage systems; however, overall yield decreases were noted in north-central states and Canada (Table 1). No-till systems do not perform as well when soil drainage problems exist. Many of the tillage studies that are cited in reviews did not have a stable no-till system in place prior to initiating an experiment, which may bias the results. Overall, the outcome of each different tillage system will depend upon the individual field and production practices.

 Table 1. Yield comparisons for no-till and other tillage systems expressed as percent yield advantage (+) or disadvantage (-) for no-till1
 
Corn
Soybean
 Region
 
 Northern
 -5.5%
 -3.9%
 Central
 -1.8%
 -0.6%
 Southern / Western
 +12.2%
 +5.0%
 Soil drainage
 
 Moderate / well drained
 +2.0%
 +2.0%
 Poorly drained
 -4.5%
 -1.4%
 Crop rotation
 Corn / soybean
 +1.9%
 +0.7%
 Continuous corn
 -1.5%
 +1.1
 
 

Types of Tillage Systems

The intensity of soil disturbance and the number of operations can be used to define a tillage system (Table 2). Primary tillage is deep tillage (> 6 inches) that loosens and fractures the soil for weed control and incorporation of residue, fertilizer, lime, and manure. Shallow tillage (< 6 inches) kills weeds, cuts and covers crop residue, incorporates herbicides, and prepares a seedbed. In-season tillage for weed control or incorporating fertilizer or manure is considered tertiary tillage.2

 Table 2. Typical field operations for several tillage systems
 System
 Typical field operations
 Plow
 Fall or spring plow, two spring diskings or field cultivations, plant, cultivate
 Chisel
 Fall chisel, one to two spring diskings or field cultivations, plant, cultivate
 Disk
 Fall or spring disk, spring disk and/or field cultivate, plant, cultivate or post-emergence spray
 Stubble mulch
 Blade plow in summer, one or more shallower operations with wide sweeps or a field cultivator, one or more rod weedings, drill, post-emergence spray
 Ridge-till
 Shred corn stalks, plant on ridges, cultivate for weed control, rebuild ridges
 Strip-till
 Strip-till, spray, plant, post-emergence spray as needed
 No-till
 Spray, plant, post-emergence spray as needed
 Source: University of Nebraska CropWatch Tillage website - http://cropwatch.unl.edu.

 
 



  • Conventional tillage. A primary tillage system that involves multiple tillage passes that disturbs 100% of the soil surface (full width), including moldboard plowing, that leaves less than 15% residue on the soil surface after planting. ​
  • Reduced tillage. A full-width tillage system that leaves 15 to 30% residue cover after one to three tillage passes. 
  • Mulch tillage. A one to three pass, full-width tillage system using a chisel, disk, field cultivator, or a combination of tillage tools that leave more than 30% residue cover after planting. 
  • Ridge tillage. A minimum tillage system where the soil is left undisturbed from harvest to planting except for 4- to 6-inch high ridges built during row cultivation. One to two inches of the ridges is scraped off during planting. 
  • Strip tillage. A minimum tillage system where the soil is left undisturbed except for strips where the soil is tilled and residue removed to facilitate planting. A mole knife is used to till a zone about 10 inches wide and 4 to 5 inches high and fertilizer is applied in the zone. 
  • Vertical tillage. A full width, shallow (2-3 inches) tillage system leaving 30% or more surface residue; used to cut, mix, and anchor residue in the upper few inches of soil and break up surface compaction and crusting. 
  • No-till. A system with a minimal amount of soil disturbance (> 70% residue cover) which uses a row cleaner, coulter, seed opener, or another planter attachment to facilitate planting.
 

Making Tillage Decisions

Each tillage system has advantages and disadvantages that need to be assessed for each field situation (Table 3). Selecting the best tillage system for a specific situation requires consideration of several factors.4 

  • Crop rotation. The amount and durability of the residue left in the field is crop specific. Corn generates more residue that degrades slower than soybean residue. It may be difficult to maintain adequate residue cover in crops following soybean.​
  • Erosion potential. The length and steepness of the slope, topsoil depth, and soil texture determine the erosion potential of a field. Highly erodible soils may require a large reduction in tillage operations to maintain residue and crop productivity
  • Internal drainage. Poorly drained soils usually require more tillage to help with warm-up and drying. High levels of residue may keep soils cool and wet too long for sensitive crops. 
  • Surface compaction. Primary tillage may be needed to alleviate compaction caused by field activities on wet soils. 
  • Nutrient management. Tillage may be needed to incorporate fertilizers. Surface applied nitrogen needs incorporation to minimize volatilization and runoff losses. Tillage should be used to incorporate broadcast applications of phosphorus and potassium.
  • Pest management. Reduced tillage systems may have more weed, insect, and disease problems than conventional systems. Residue cover can serve as an overwintering site for some insects and diseases, or delay crop development due to cool, wet soils, increasing the risk of early season disease and insect problems. Tillage can bury weed seed, disrupt weed, disease, and insect lifecycles, and bury residue that harbors pests. 
  • Planting equipment. Planter modifications (coulters, row cleaners, starter fertilizer attachments) may be required to handle higher crop residue levels in conservation tillage systems. Planting equipment specific to a strip-till, ridge-till, or no-till system may be required to match tillage and planting operations in each system.  
 Table 3. Advantages and disadvantages for several tillage systems
 System
 Advantages
 Disadvantages
 Plow
 Suited for poorly drained soils; excellent incorporation; provides a well-tilled seedbed
 Major soil erosion; high soil moisture loss; highest fuel and labor costs
 Chisel
 Less winter wind erosion from roughened soil surface; well adapted to poorly drained soils; good incorporation
 Little erosion control; high soil moisture loss; shredding may be needed for residue flow; medium fuel and labor requirements
 Disk
 Less erosion with more residue; well adapted for well-drained soils; good incorporation
 Little erosion control with more operations; high soil moisture loss; destroys soil structure; compacts wet soil
 Ridge-till
 Excellent for furrow irrigation or poorly drained soils; ridges warm up and dry out quickly
 No incorporation; wheel spacing and other machinery modifications may be needed; creating and maintaining ridges
 Strip-till
 Tilled, residue-free strips warm up quickly; injection of nutrients into row area; well suited for poorly drained soils
 Cost of pre-plant operation; strips may dry too much, crust, or erode without residue; not suited for drilled crops; possible RTK guidance costs
 No-till
 Excellent erosion control and soil moisture conservation; minimum fuel and labor costs; builds soil structure and health
 No incorporation; increased dependence on herbicides; slow soil warming on poorly drained soils
 Source: University of Nebraska CropWatch Tillage website - http://cropwatch.unl.edu.