Minimum tillage includes cultivation activities that do not include inversion of soil, cause minimum soil disturbance, and limits the number of passes over the field. Minimum tillage practices that cause more than 30% residue cover can be considered conservation tillage. This post will discuss the various tillage systems considered under this category, their benefits, disadvantages and considerations.

Minimum tillage, as the name suggests, encompasses tillage practices where minimal soil disturbance occurs using discs or tines (tooth harrows) up to 2-4 inches or in narrow strips where future crops will be planted (strip tillage). Minimum tillage follows a principle of mixing previous crop residues with soil producing a surface soil tilth for the next crop. The depth to which minimum tillage is carried out is determined by the existing compaction and residue incorporation requirements. It can be shallow (2-4 inches) or deep (8-14 inches). Minimum tillage equipment can mix the soil using disc or tine coulters and level the seedbed after using a packer or roller. Discs can be used in drier soils, while tines can be used over wider soil moisture conditions. The minimum tillage practice suited to prepare your field for crop cultivation can be decided based on the soil texture, moisture content, and the crops in consideration. 

Minimum tillage includes the following tillage practices: 

Strip tillage: Involves tilling of a strip of seed row(flexible depth) prior to planting, helping with better root penetration, compaction control, enhanced soil drying, and warming. A good alternative to no-till on fine textured and compacted soils. However, it is costlier and energy-intensive than no-till and does not prevent weeds and compaction in inter-rows. 

Ridge tillage: Minimum tillage system where crops are planted on raised seed beds/ridges (4-6 inches high) formed with a ridge-till cultivator. Facilitates seed zones on ridges to dry and warm more quickly. Raised seed zones are less prone to getting saturated with excess rainfall. This tillage system can be hard with sod and narrow-row crops. The wheel spacing must be constant with fixed travel lanes for this tillage system to work. 

Mulch tillage: Conservation tillage system (>30% residue cover) achieved using conventional tillage equipment like disks, chisel plows, or field cultivators run with limited passes across the field. It can be considered a minimum tillage practice as it involves tilling soil without inversion. Chisel plows are primary tillage equipment that lifts and shatters soil with chisels, shovels, or sweeps but does not involve inversion. Coulter-chisel plows come with disks or coulters in addition to chisel teeth. The coulters/discs help with cutting the residues leaving 30-75% residues after a single pass. Discs leave 30-70% residues, and usage should be avoided under wet conditions. 

Higher residue on the field can require additional equipment adjustments like coulters or trash whippers to move the crop residues from the crop row. This can help with preventing soil moisture retention on rows that can lead to seeds being disease susceptible. There is a need for monitoring for smearing and compaction, as running discs under unfavorable soil moisture conditions can cause that. Taking care of the timing of tillage operation, effective weed control, and nutrient management via regular soil testing needs to be included in the system to ensure success. Incorporation of cover crops and crop rotation can help add cover, weed control, nutrient cycling, soil quality enhancement, and pest cycle breaking. In soils with weak drainage, structure, and high compaction, beginning with minimum tillage for a slower transition to no-till can be more effective. 

A 40% or more reduction in the number of passes can be expected with minimum tillage in comparison to conventional tillage. The reduced number of tillage passes leads to less labor and time requirements with more energy conservation and less machinery wear. Incorporating minimum tillage practices provides not only economic benefits but also agronomic and environmental benefits wherein soil productivity and quality can be enhanced by improvement in soil structure, better water infiltration, less erosion, better nutrient retention, enhanced biodiversity, more organic matter, and lesser greenhouse gas emissions. Farmers who are practicing conventional tillage can consider making the slow transition to no-till by resorting to minimum tillage operations for a start. They may need to go through a learning curve to comprehend and adjust to new management as they switch from conventional tillage to min-till management. In order to properly apply this approach, join our extension and education activities.