When experimenting with till versus no-till, what constitutes tillage?

Answer: A good definition of tillage is the preparation of soil by mechanical agitation for planting crops. Any disturbance, small or large, that prepares the soil for planting constitutes tillage. One type of tillage is primary tillage, which is the breaking up of sod ground or other ground that has not been worked for planting for a long time. This consists of plowing deeply and turning sod and residue into the ground. This was traditionally done with a moldboard plow and can leave the soil vulnerable to erosion. Chisel plows and heavy disc harrows can also be used for primary tillage and will leave residue closer to the soil surface. Secondary tillage is not as deep and is used to prepare a finer seedbed for planting. A disc harrow, spike tooth harrow or a rototiller would be examples of secondary tillage equipment.Cultivation for weed control with mechanical cultivators or a hoe can also be considered tillage of the soil, even though it only works the top few inches of soil. There are many advantages to no-till and reduced tillage, including better soil health, reduced erosion, reduced energy use, and water conservation. Organic no-till systems are really reduced tillage systems because some form of primary tillage is needed to control weeds. Herbicides are used for this in conventional no-till so the ground doesn’t need to be tilled prior to planting. Once weed control is achieved in an organic system, and a cover crop is established, then a cash crop can be planted without additional tillage. No tillage is needed for about five seasons, after which weeds may once again become a problem. The ATTRA publication Pursuing Conservation Tillage for Organic Crop Production describes the methods and strategies used to reduce tillage in an organic system. Conservation tillage refers to a number of strategies and techniques for establishing crops in the previous crop’s residues, which are purposely left on the soil surface. The principal benefits of conservation tillage are improved water conservation and reduced soil erosion. Additional potential benefits include reduced fuel consumption, flexibility in planting and harvesting, reduced labor requirements, and improved soil tilth. Two of the most common conservation tillage systems, ridge tillage and no-till, are discussed in this ATTRA publication.Rodale Institute has been researching and practicing organic no-till techniques. You can read about their equipment and systems at http://rodaleinstitute.org/our-work/organic-no-till/.