Strip tillage for high-residue irrigated cropping systems
O. Steve NorbergFigure 5. GPS receiver and antenna for RTK correction mounted on top of a tractor cab. When dealing with high-residue irrigated environments in the Pacific Northwest, handling the residue in a way that allows for successful seeding is a must. When harvesting the previous crop, using a chaff spreader to spread chaff back over the width of the combine header reduces problems with seedling emergence (figure 8).
Advantages of Strip Tillage Compared to Conventional Tillage
Compared to conventional tillage, strip tillage reduces water and wind erosion, especially in sandy soils, where stands can be lost each spring in wind storms. Strip tillage can greatly reduce this problem by leaving wheat stubble upright or by growing a cover crop and killing it prior to planting, both of which reduce soil movement and protect young seedlings (figure 9).
click image to zoomobert G. Evans, W. Bart Stevens, and William M. IversenFigure 6. Components of a strip tillage unit used in a two-pass system that uses mechanical markers for both the next pass and for the planter and does not require GPS for guidance. Strip tillage reduces soil stirring compared to conventional tillage, which improves soil organic matter content and reduces CO2 losses from the soil (USDA Natural Resource Conservation Service n.d.). Keeping residue on the soil surface helps prevent snow from blowing away and reduces soil evaporation to the atmosphere. Reducing tillage reduces the labor and fuel required per area cropped. Crop residue provides food and protective cover for wildlife. Some day you may even get sellable carbon credits associated with strip tillage and carbon retention.
click image to zoomRobert G. Evans, W. Bart Stevens, and William M. IversenFigure 7. Components of a planter following the strip tillage unit in a two-pass system. Notice ribbed tires to aid in following the mark made by the strip tillage unit and row cleaners placed ahead of planting units. Water savings is another potential advantage of strip tillage. Research from the arid state of Texas on strip tillage in cotton production showed that strip tillage compared to conventional tillage reduced water loss from the soil (evaporation) by 39%, saving 2.5 inches of water (Lascano et al. 1994).
Disadvantages of Strip Tillage Compared to Conventional Tillage
To be successful, strip tillage will require more management, skill, and planning than conventional tillage. Conventional tillage stirs the soil more thoroughly, incorporating more residue than strip tillage and making planting easier. Conventional tillage does not require as precise driving when planting. Conventional tillage may allow more flexibility in timing for weed control; however, if herbicide-resistant varieties of crops are available, this is not much of an issue. Thus, for strip tillage, different management practices and knowledge will likely be required in the areas of residue management, weed management, and seed placement with planter (figure 10).
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