ECOLOGICALLY-SOUND PEST, WATER AND SOIL MANAGEMENT STRATEGIES FOR NORTHERN GREAT PLAINS CROPPING SYSTEMS
Location: Agricultural Systems Research Unit
Title: Where does Strip Tillage Fit in Montana Irrigated Crops
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 7, 2009
Publication Date: January 12, 2009
Citation: Stevens, W.B., Evans, R.G., Iversen, W.M. 2009. Where does Strip Tillage Fit in Montana Irrigated Crops [Abstract]. 21-23.
Strip tillage, which is sometimes called zone tillage, row clearing or inter-till, is a form of conservation tillage for row crops where only the soil immediately within the crop row is tilled. The tilled strip can vary from 8 to 12 inches wide and from 2 to 14 inches deep leaving standing stubble and detached crop residue between the tilled strips. Depending on crop row spacing the amount of a fields surface area that is tilled varies from 25% to 50%. Strip tillage is a represents a compromise between conventional practices and no-till by achieving a favorable seed-bed similar to conventional tillage along with many of the soil conservation benefits of no-till. Strip tillage systems were developed several decades ago, but adoption has increased notably during the past ten years. It has become fairly widely used in rainfed areas on large seeded crops like corn, soybeans, cotton, and peanuts. However, development of strip tillage for small seeded crops like sugarbeet has been slow, but that is rapidly changing.
The growing interest in strip tillage is a result of several potential advantages compared to conventional tillage practices. Since seedbed preparation and fertilizer application can be accomplished with one pass instead of the multiple tillage passes required for conventional tillage, there can be substantial savings in fuel and labor costs. Lower tillage intensity can preserve soil carbon potentially enhancing soil organic matter content, tilth and structure which in turn promote good soil fertility and water infiltration. Standing stubble protects seedlings from wind-blown soil and increases the amount and uniformity of snow capture during the winter. Crop residues on the soil surface help reduce moisture loss by evaporation. Shank-type strip tillers provide a convenient way to band fertilizer within the root zone, which typically increases fertilizer use efficiency.
There are, of course, challenges that need to be considered when converting to strip tillage. Equipment conversion can be costly and horsepower requirements are high, ranging from 20 to 30 horsepower per row for tillage depths of about 8 inches. Traditional weed control practices may be more difficult with strip tillage because residue from the previous crop can interfere with cultivating and spraying operations. This has been overcome in most situations by using high-residue cultivators and Roundup Ready® cultivars and hybrids. Insects and diseases can also be more of a problem when the previous crop’s residues are left on the soil surface. More careful field scouting may be necessary to ensure that any cutworm activity and disease incidence are detected early. On heavy soils, strip tillage must be done when the soil moisture is moderate. Tilling when the soil is too wet will fail to shatter the soil adequately and will lead to plugging of the strip tiller when there is an abundance of residue. If the soil is too dry, strip tillage will leave hard clods that may not mellow before planting time, leading to a poor seedbed. Fall strip tillage performed when soil moisture is moderate has consistently produced satisfactory seed bed conditions for spring planting. Strip tilling in the fall seems to work best for heavy soils, whereas spring strip tillage should work well for lighter sandy soils
One of the most frequently mentioned difficulties with strip tillage is accurately following the tilled strips with the planter in the spring. Tilled strips can be difficult to see in the spring after fall tillage because of blowing residue. The use of guidance ridges, furrows or high-precision (RTK) GPS guidance of tractors and equipment has greatly helped. Finally, much of the successful implementation of strip tillage has occurred under rain-fed or sprinkler-irrigated conditions with wide row spacing (30 to 36 inches).
Narrower rows increase the likelihood that residue will plug the strip tiller, especially under wet conditions and reduced the amount of undisturbed residue remaining after tillage. Much less strip tillage has been done under furrow irrigation because forming a clean furrow that will allow irrigation water to flow freely is more difficult than with conventional tillage; however, we believe that these techniques may also work on furrow irrigated fields, although some modifications may be required to handle the residue effectively.
Strip tillage offers both potential advantages and challenges for Montana and Wyoming crop producers. Reduced fuel and labor costs and improved soil quality can benefit all operations. Protection of seedlings from wind-blown soil can be particularly valuable on sandy and other easily erodible soils. Grower experience and field research from Idaho, Montana, Wyoming and North Dakota have shown that corn, dry bean, sugarbeet, soybean, and sunflower have consistently yielded as well under strip tillage as under conventional management. Strip tillage fits well with sprinkler irrigation, while growers with heavy soils, narrow row spacing and furrow irrigation will need to give careful consideration to the challenges that these factors presents for successful implementation of this tillage system.