Strip-Till Systems for Corn Production
Crop Insights written by Andy Heggenstaller, Agronomy Research Manager
- Strip-till is a form of minimum tillage best suited to areas where no-till is not well adapted for corn production due to cold, heavy, compacted and/or poorly drained soils.
- In a strip-till system, seeds are planted into narrow strips of tilled soil that are created prior to planting.
- When properly implemented, strip-till can offer the seedbed advantages of full-width tillage along with the soil conservation benefits of no-till.
- The four most common strip-till methods are: fall strip-till; spring strip-till; zone-till; and in-row subsoiling. Each system offers advantages and drawbacks depending on field conditions and crop management system.
- In most strip-till systems, N, P and K fertilizers are subsurface-applied in the row area at the time of strip preparation, which can increase nutrient availability to seedling plants and decrease the chance of nutrient loss.
- Strip-till can deliver better continuous corn yields than no-till due to improved seedbed uniformity and reduced plant-to-plant variability.
Although reducing tillage intensity can provide conservation benefits and cost savings, adoption of no-till and minimum till practices for corn production has been limited in some areas, particularly in the northern Corn Belt. Cold, poorly drained soils and a shorter growing season there can lead to delayed planting, low and uneven emergence and lower yields for reduced vs. conventional tillage. Strip-till has been proposed as an alternative minimum tillage system for areas and soils that are not well suited for no-till management.
Strip-Till Concept and Benefits
Strip-till is a method of seedbed preparation in which confined strips of soil are tilled prior to planting. Seeds are then planted directly into tilled strips, leaving inter-row areas protected by residue while avoiding residue contact with seeds and seedling plants (Figure 1). Interest in strip-till has increased in recent years due to evidence that it combines many of the best aspects of no-till and conventional tillage systems.
|Figure 1. Corn seedling emergence and early growth benefit from reduced in-row residue in a strip-till system. Photo courtesy of Liz Stahl, University of Minnesota.|
Benefits over no-till: Tilling in the row area encourages more favorable soil temperature, moisture and aeration conditions for germinating seeds and seedling plants, which can translate to improved crop establishment and early season performance. In addition to potential seedbed preparation advantages, strip-till also offers the opportunity to place fertilizers directly in the root zone, away from crop residues that could otherwise intercept or immobilize nutrients.
Benefits over conventional tillage: Strip-till can provide conservation and efficiency benefits over conventional tillage practices. Leaving the inter-row area untilled retains crop residues on the soil surface, providing increased erosion resistance and increased organic matter inputs. Strip-till can also reduce field passes and input costs compared to conventional tillage (Table 1).
|Tillage System||Field Operations||Minimum Field Passes|
|No-till||Apply N; Plant (apply P and K w/planter)||2|
|Strip-till||Strip Preparation (apply N, P and K w/tillage); Plant||2|
|Reduced tillage||Apply N; Apply P and K; Field Cultivate; Plant||4|
|Conventional tillage||Apply P and K; Chisel Plow; Apply N; Field Cultivate; Plant||5|
Strip-till is a general term used to describe a group of related tillage systems that share common practices and equipment, but have different names and specific management elements that vary by state or region. The four most commonly used forms of strip-till are: fall strip-till; spring strip-till; zone-till; and in-row subsoiling.
Fall strip-till is the most commonly practiced strip-till system and is implemented by preparing 6- to 10-inch wide and 6- to 8-inch deep strips in the fall and planting directly into these without further tillage in the spring. As in most other strip-till systems, injection knives that are able to accommodate application of both anhydrous ammonia as well as dry (P and K) fertilizers can be used to prepare strips and make preplant fertilizer applications with a single field pass.
|Figure 3. Strip preparation and preplant fertilizer application are often completed in a single-pass in a strip-till system. Photo courtesy of Case-IH.|
Spring strip-till is typically the same as fall strip-till in terms of equipment and field operation, but with strip preparation occurring in the spring, directly prior to planting. The decision of whether to prepare strips in the spring versus fall depends on several issues, including field drainage and nitrogen management strategy. Many producers, especially those managing poorly drained soils, prefer to prepare strips in the fall due to improved field access and tillage conditions. In contrast, other producers choose to prepare strips in the early spring when opportunities for N loss are reduced.
Zone-till is similar to other strip-till methods in terms of management objectives, but uses less aggressive equipment. In a typical zone-till system, planting bands are created by coulters that disturb the soil to a depth of only 1 to 2 inches. In soils where subsurface compaction is not a problem, zone-till can deliver the same advantages as conventional strip-till, with lower horsepower requirements.
In-row subsoil tillage is often used in soils where subsurface compaction is a concern. In-row subsoil tillage consists of a series of straight leg shanks that disturb narrow soil zones, but can be adjusted to operate to a depth of 20 inches or more. In-row subsurface tillage is used to alleviate compaction layers in the area where the seed will be placed, and is often used in conjunction with zone-till equipment to create a planting band that is equally as wide as that produced in other strip-till systems.
Typical equipment requirements for strip-till include a heavy tool bar to which row markers, opening coulters, knives and covering disks are attached. Rolling harrow baskets and other seedbed conditioner attachments are often added to the back of the unit as well (Figure 4).
|Figure 4. Basic components of a typical strip-till unit include: (1) opening coulter; (2) residue managers; (3) mole knife/NH3 injector; (4) covering disks; and (5) seedbed conditioner. Photo courtesy of Yetter Manufacturing.|
Zone-till units differ from those used for conventional strip- till in that they consist of a set of two or three offset, wavy or fluted coulters that disturb the soil surface only. In cases where subsurface compaction prevents the use of zone-till, in-row subsurface tillage units (referred to as “zone builders”) can be used in place of or in conjunction with zone-till equipment to achieve a restricted tillage band (Figure 5).
|Figure 5. Zone builder unit used for in-row subsoil tillage. Photo courtesy of Unverferth Mfg. Co., Inc.|
In order to maximize fertilizer efficiency gains in strip-till systems, N, P and K are best applied at the time of strip preparation. If strips are prepared in the spring and anhydrous ammonia is used as a source of N, application should occur at least two weeks before planting and at full tillage depth (6 to 8 inches) to prevent ammonia toxicity. Other fertilizer considerations for strip-till include:
- Fertilizer nutrients should be placed 3 to 6 inches below seeding depth in the tilled strip to optimize their location for early access by seedling plants.
- Banded application of less mobile nutrients like P and K can improve fertilizer efficiency on soils that have a low CEC or that have low to very low test levels.
- Subsurface fertilizer placement generally reduces the likelihood that soluble nutrients will be lost as run-off.
|Tips for Successful Strip-till|
Crop Rotation and Corn Yields
The advantages of strip-till are generally most pronounced for corn following corn, where strip-till can help improve seedbed uniformity and reduce plant-to-plant variability compared to no-till. In a four-year, continuous corn study conducted on a loam soil in northern Indiana, corn yields under strip-till were 5% greater than in no-till, and within 1% of full-width tillage (Figure 6). In the same study, however, corn yields were similar for strip-till, no-till and full width tillage when corn was rotated with soybean. On cooler, poorly drained soils, strip-till can also provide a yield advantage over no-till when corn is rotated with soybean (Vetsch et al. 2007).
|Figure 6. Corn yield response to rotation and tillage system in a four-year study conducted on a loam soil near Wanatah, IN (Vyn et al., 2006).|
USDA Strip-Till Incentive Program
In many states, the USDA's Natural Resources Conservation Service (NRCS) provides incentives through the Environmental Quality Incentives Program (EQIP) for transitioning to strip-till or no-till. Funds received through the EQIP program can be used to defray the costs of purchasing strip-till equipment. Details of EQIP vary by state and county, but payments for transition to strip-till are typically in the range of $15 to $30/acre during the transition year, with limitations on total payment received and acres enrolled. For more information about financial support for transition to strip-till, visit the NRCS EQIP web site or your local USDA Service Center.
Randall, G., and P. Hill. 2000. Fall strip-tillage systems. p. 193-199. In R. Reeder (ed.) Conservation Tillage Systems and Management. MWPS-45. Midwest Plan Service. Ames, IA.
Vyn, T.J., T.D. West and P. Walker. 2006. Agronomic impacts of strip tillage and new reduced tillage systems in corn production. Pioneer Crop Management Research Award Summary.
Vetsch, J.A., G.W. Randall, and J.A. Lamb. 2007. Corn and soybean production as affected by tillage systems. Agronomy Journal. 99: 952-959.