Tillage Intensity to Maintain Target Residue Cover (NRCS 329, 345 & 346)

Effectiveness

A long-term Ohio study on two different soils found that infiltration rates were at least 1.9–4.2 times greater under a no-till system when compared to those under minimum tillage and conventional moldboard plowing to 25 cm followed by secondary tillage to 10 cm. Reduced-till was comprised of chisel plowing, without soil inversion, to 25 cm followed by cultivation to 10 cm before planting. The study also found that soils in the no-till system had higher soil organic carbon, improved or maintained soil tilth, enhanced aggregate stability, and higher available water content (Kumar et al., 2012).

Diesel fuel use comparisons of different tillage systems determined that a conventional system used 5 gallons/acre, a mulch-till system used 4 gallons/acre, and a no-till system used 3 gallons/acre (NRCS Energy Estimator Tool). NRCS expects the total energy consumption associated with conservation tillage to be reduced by at least 20 percent compared to the conventional tillage. Reduced tillage systems also conserve fuel and reduce labor needs on the farm. Less soil disturbance equals less horsepower needed per pass. Tillage passes can be replaced by a pass made with spray equipment making an herbicide application. Diesel fuel use in in different tillage systems has  been calculated with a plowed system using 5.28, chisel 3.34 and no-till at 1.35 gallons per acre.

Conservation tillage practices, including reduced tillage and no-till, leave more crop residue on the soil surface after planting and reduce root zone disturbance resulting in reduced erosion and improved soil tilth. Water infiltration and structure is improved by preservation of natural channels formed by cracks, fissures and biopores. In a long-term study in Ohio on two different soils, Kumar et al. (2012a) found that infiltration rates were at least 1.9 to 4.2 times greater under no-till when compared to those under minimum tillage and conventional moldboard plowing to 25 cm followed by secondary tillage to 10 cm. Reduced-till was comprised of chisel plowing, without soil inversion, to 25 cm followed by cultivation to 10 cm before planting. They also found that soils in the no-till system had higher soil organic carbon, improved or maintained soil tilth, enhanced aggregate stability, and higher available water content (Kumar et al. 2012b).

Organic matter is improved with reduced soil disturbance. Introducing oxygen through tillage activities results in oxidation of organic matter. The short-term benefit of oxidation of organic matter is the release of plant available nutrients but the long-term impact of reduced organic matter is the reduction in water holding capacity, loss of soil tilth and natural nutrient cycling capacity of the soil. For each 1% increase in soil organic matter, water holding capacities will increase 0.75 to 1 inch.

Conservation Tillage leaves significant residue cover to provide for erosion control during the non-growing portions of the season. Maintaining a targeted level of 30% residue cover after planting is recommended to provide enough cover to reduce soil losses. The guide Farming with Crop Residue provides a pictorial view of residue in corn and soybean systems.

Considerations

Maintaining a targeted level of 30 percent residue cover after planting is recommended to provide enough cover to reduce soil losses. NRCS’ guide Farming With Crop Residue provides a pictorial view of residue at different levels of cover in corn and soybean production systems.

Reducing tillage results in system changes that must be accounted for to be successful. Drainage, pH and weed problems should be addressed before moving to no-till.

Drainage and soil type considerations in adoption of no-tillage.

Soil characteristics greatly influence the crop yields obtained using no-till and other forms of conservation tillage. While it may be possible for a few producers to produce a crop (and even make money) using these systems on any field, maximum returns are normally achieved by matching the proper tillage systems to the soil at hand. In general, as soil drainage becomes better, tillage can be reduced further.

Well-drained soils, such as Wooster, Fox, Miamian-Celina, or Morley-Glynwood, often become moisture deficient as the growing season progresses. The mulch provided by no-tillage planting normally conserves some water and maintains infiltration on these soils by reducing crusting. As a result, the yield potentials of such soils are usually higher under no-till than under moldboard plowing. Intermediate tillage, such as chisel plowing, usually produces yields intermediate between moldboard plowing and no-till.

Somewhat poorly drained soils, such as Blount, Crosby, and Fincastle, can be no-tilled with careful management. These soils produce the best yields under no-till if they are systematically drained and crops are rotated. If drainage is not provided, chisel-plowing may provide the best yields under conservation tillage. If adequate drainage and residue are present, yields produced with conservation tillage should be equal, on the average, to those obtained by plowing, though different systems may produce the highest yields in different years. These soils crust severely, and in some cases, use of a carefully managed cover crop may be necessary when planting into soybean stubble to ensure adequate surface protection and infiltration. This latter point is most important during the first few years of no-till on such soils.

Poorly drained soils that respond to subsurface drainage improvements, such as Kokomo, Pewamo, and Hoytville, may be adapted to no-till production. Improved drainage and crop rotation are essential to producing top yields. If drainage and rotation are not used, yields under no-till may be much lower than had the field been plowed. No-tillage soybeans may be successful if drainage and rotation recommendations are followed and precautions for preventing Phytophthora root rot are taken. Soils such as these are considered to be among the most productive in Ohio when plowed and will produce very high yields under conservation tillage as well, if managed properly.

Wet, poorly drained soils, such as undrained Hoytville, or soils that do not normally respond well to tile, such as Clermont, Mahoning, and Paulding, are not normally recommended for no-tillage because surface residue often creates severe moisture excesses. Ridge planting may offer a more attractive alternative on such soils because the elevated ridge dries more quickly in the spring and may allow for significantly earlier planting, which can raise yield potentials. Crop rotation is a must on these soils to avoid low yields, regardless of tillage system used.

pH and Liming

Soil pH governs nutrient availability and water pH of 6.5-6.8 tend to result in the greatest availability of soulable nutrients we want to have available to the crop. When converting from a more aggressive tillage system to a lower intensity tillage system is being considered, a soil sample to measure soil available nutrients and pH should be done. Soil pH is most easily and quickly corrected when a lime source can be thoroughly mixed in the soil profile. Once the reduced tillage system is adopted, lime correction will only be accomplished through surface application with minimal mixing resulting in delayed correction to pH. See BMP Amending Soils with Lime or Gypsum for more information on pH and liming.

Cost

Cost of equipment and the required horsepower for the tractor are the major capital costs required to change tillage systems for the farm. Used equipment may be available that will lower the initial cost of the switch. A second consideration will be labor required. Due to actual number of passes involved in the new system vs current practices, more or less labor may be involved.