Reasons for Tillage
There are many reasons to perform tillage for crop production in addition to increasing soil dry-down. Soil is also tilled for reasons such as:
- Weed control
- Soil levelling to improve seedbed uniformity
- Incorporation of crop residues
- Incorporation of manure and/or fertilizer
- Wireworm and grub protection
- Seed bed preparation
Herbicides have resulted in reduced need for tillage to control weeds, except in organic production systems. And the development of equipment capable of planting into crop residue ensures that crops can be planted successfully with little or no tillage.
Generally performing primary tillage operations in the spring will leave the soil less prone to erosion than tillage in the fall. From an economic and environmental perspective it is best to use the least amount of tillage necessary. This will help to keep the soil in place and prevent soil movement to water courses.
Considering all parts of the system will improve the success of any tillage system. For example:
- Uniform distribution of crop residue and chaff at harvest will improve tillage and planting operations.
- A diverse crop rotation can reduce insect, disease and weed issues and can incrase the potential success with reduced tillage.
- Adapting ther planter or drill for specific soil texture and/or crop residue type, over and above the addition of coulters or residue wheels, can improve seed placement.
A number of different tillage systems are used in Ontario. These are summarized below but covered in more detail in the tillage section.
Conventional Tillage
Conventional tillage in Ontario generally consists working the entire soil profile with primary tillage equipment followed by secondary tillage (usually in the spring ahead of planting). The more uniform and level a field is left after fall primary tillage, the greater the opportunity to reduce secondary tillage costs and improve planter/drill performance. A lack of surface residue in conventional tillage exposes fields to great risk of erosion from water and wind. On complex slopes, tillage erosion can be responsible for causing large quantities of topsoil to move to lower slope positions.
Fall Mulch Tillage
Also referred to as conservation tillage or chisel plowing, mulch tillage tools usually leave more (greater than 30%) residue on the soil surface. The soil surface is left level in the fall so that single-pass planting can occur or planting can occur with minimum secondary tillage.
Vertical Tillage
Vertical tillage is used to reduce the pushing or smearing action that can be cased by tillage tools. Many verticlal tillage tools are designed to size residue into more manageable pieces and distribute crop residue, while causing some soil fracturing and mixing of soil with residue at the surface. A number of tillage tools are available that embrace the concept of “vertical” tillage, but use shallow concave discs, low profile sweeps and extensive harrows to provide some additional soil disturbance – all the while attempting to remain true to the idea of tillage without significant inversion and soil smearing.
Spring Mulch Tillage
Eliminating fall tillage is the best practice for reduing soil erosion. Producers working with fine-textured soils, especially with high residue crops such as corn or wheat may be apprehensive about leaving soils untouched, however following low-residue crops, such as soybeans or dry edible beans, there is little justification for conducting fall tillage. Considerations for eliminating fall tillage include risk of soil erosion, availability of equipment to handle spring residue and field drainage. Best results with spring mulch tillage occurs with the use of high-clearance tines, narrow teeth and/or packers or rollers used in conjuction with the field cultivator.
Strip Tillage
Performing tillage that is confined to narrow zones corresponding to the rows of the next crop allows strips of soil to be loosened and cleared of residue while leaving the rest of the field covered with protective crop residue. When performed in the fall, the strips are often drier and more suited to “no-till” planting. Most spring strip tillage are restricted to lighter soils and are performed within hours of planting. Strip tillage provides the opportunity to apply all or part of a crop’s fertilizer needs.
Deep Tillage
Increasing axle loads from farm machinery, and the general concern that soils have become more compacted have increased the use of deep tillage systems. The main reason offered for deep tillage is the elimination of compacted sub-soil layers and or tillage “hard pans” to promote deep root growth and improve drainage. Deep tillage into dry soils combined with deep-rooted crops (alfalfa, sweet clover) offer the best opportunity for repairing compacted soils.
No-Till Systems
In no-till systems, tillage is not used to prepare a seedbed. Minimal soil loosening occurs in a narrow band immediately ahead of the seed opener. Planter accessories such as coulters or residue clearing tools can be essential for success. Successful no-till crop production is dependent of effective use of alternative production practices and field management strategies. For successful no-till production it is important to:
- have good soil drainage and water infiltration.
- start with adequate soil fertility levels, especially pH, and consider fertilizer placement stragegies.
- maintain a multi-year crop rotation.
- incorporate weed control strategies without use of tillage.
- manage diseases and insects.
- incorporate residue management to maintain some soil cover all year.
- minimize compaction.
Rasmussen, K.J., and E. Moller. 1981. Regrowth after pre-wilting of grassland crops. II. Soil compaction in connection with harvest and transport. Tidskr. Planteavl. 85: 59-71 (In Danish, with English summary).
Chamen, W.C.T., A.P. Moxey, W. Towers, B. Balana and P.D. Hallet. 2015. Mitigating Arable Soil Compaction: A Review and Analysis of Available Cost and Benefit Data. Soil & Tillage Research. 146: 10-25.