Strip-till implements provide an excellent means of deep banding fertilizer, which will improve efficiency and reduce the risk of nutrient loss to the environment. Soil erosion potential in a strip-till system will be intermediate to the high risk of conventional tillage systems and the very low risk seen in no-till systems.
A Solution For Cold, Wet Soils
No-till has been largely successful at reducing soil loss from erosion. It also has proven to be better at retaining moisture by improving infiltration and reducing evaporation.
On heavy soils in moist environments, high residue levels have delayed planting and resulted in poor early seedling vigor. This has been a problem for corn production in the Midwest.
Strip-till was designed primarily to help improve the seedling environment in early spring. Tillage in the fall or spring helps reduce residue levels, dries excess soil moisture and causes soil temperature to rise because of increased exposure to the sun.
To gain the benefits of tillage in the seed zone, while retaining the needed soil-erosion and moisture-saving benefits of no-till, a hybrid tillage system, strip-till, was created.
This new equipment varies by manufacturer, but in a basic configuration consists of coulters, discs and a subsurface knife for injecting fertilizer. Strip-tillage can be performed in the fall or spring before planting. Tillage equipment must be designed to match planting equipment because consistent seed placement within the tilled area is critical to gain the benefit of the tilled strip.
Strip-till performance is still being evaluated, as this practice is fairly new. In the upper Midwest, some research shows continuous-corn production using strip-till has improved over no-till.
As predicted, crop emergence has improved with more uniform stands and better seedling vigor. In the same study, however, little response to tillage was seen in corn rotated with soybeans. Grain yields in strip-till have shown a limited advantage over no-till, varying with annual weather conditions.
Strip-Till As A Transitional Tool
Most strip-till implements have a fertilizer shank that allows placement of fertilizer within the tilled zone. Some irrigated corn producers in western Kansas now use strip-till to help manage fertilizer applications in continuous-corn systems.
In these high-yielding environments, continuous high residue levels limit adoption of no-till. Most producers apply nitrogen in the fall as anhydrous ammonia. The strip-till implement provides an opportunity to retain a large amount of residue, while clearing a path for planting and putting down more than half of the annual nitrogen requirement for corn.
These Kansas irrigators have adopted this tillage tool as a transitional tool. Without the use of strip-till, the majority of these producers would use some form of complete tillage to reduce residue in order to stay in a continuous-corn system.
Using strip-till provides a way to manage a high-residue system. Since 66% of the field retains residue in strip-till, the overall effect will improve soil and water conservation.
The lesson is that strip-till can be used to help transition traditional tillage systems into less-tillage-intensive systems. For dryland production, most no-tillers would argue that a strip-till machine isn’t necessary. They are comfortable planting through high-residue fields and managing weed and disease pressure through crop rotations.
Still many traditional producers are reluctant to try no-till. Either they lack the proper planting equipment, or feel they don’t have enough information to properly manage this new system. Strip-till may help them move to high-residue crop production systems.
Strip-Till In An Arid Environment
In dryland production in western Kansas, the factor that most limits crop yield is water availability. No-till summer crops capitalize on the moisture-saving nature of high residue levels.
Typically, the best corn is grown following wheat, Kansas’ highest residue producing crop. Strip-till reduces residue levels in the tilled strip, exposing soil to the air.
How will this affect the overall water balance for crop production? Research in the panhandle of Texas might provide insight on this subject.
In an intensively monitored research plot, estimates of seasonal evaporation were determined for cotton grown in two tillage systems. The soil water contents were measured to 10 feet, and soil evaporation rates were measured daily using micro-lysimeters.
The total evaporation from both systems were similar, but a greater percentage of water transpired through the plant where residue was retained in the strip-till system. This 37% increase in transpiration efficiency resulted in a 35% increase in lint yield.
At the end of the season, in an arid or semiarid environment, water added as precipitation or as irrigation will likely end up in the atmosphere from the large and ever-present evaporative demand. Management of the soil will dictate how that water travels to the atmosphere.
In this environment, increasing the amount of water that moves through the plant typically leads to higher yields. Maintaining higher residue, whether through strip-till management or through no-till management, should increase yield potential in western Kansas.
Soil Organic Carbon In The Balance
Soil productivity is strongly tied to soil organic matter and microbial activity. Many researchers have shown how tillage intensity reduces soil organic matter.
The most intense tillage practice involves using a moldboard plow, and all tillage practices result in a reduction of soil organic matter from that of native sod.
The greatest loss occurs with the most aggressive tillage system. Total soil nitrogen also follows this trend with tillage. Even though producers provide most of the nitrogen needed for crop production through fertilizer nitrogen applications, the ability of the soil microbiological community to hold that nitrogen and release it to a growing crop is an important factor.
In terms of tillage intensity, strip-till falls in a category between conventional tillage and no-till. Therefore, the effect it has on soil organic matter is intermediate.
Soil organic matter could improve where conventional tillers adopt strip-till, but could be reduced where no-tillers begin to use strip-till. In either case, the effect on soil organic matter should be minimal, and only measurable over long time periods.
All tillage choices should be weighed against the effects they have on natural resources. Strip-till should not be used on highly sloped ground. In this situation, exposed soil strips are subject to erosion.
This is especially risky if the strips run up and down the hill, rather than following a contour. Exposed soil in a tillage strip also might increase the risk of crusting as compared to a no-till system.
As a system for wind erosion control, strip-till should be a great improvement over a conventional-till system. The maintenance of standing residue will reduce the wind speed near the soil surface and provide sediment traps for any suspended particles. On sandy soils, place strips east to west, or at least at an angle different from the prevailing winds, to prevent the wind from blowing down the strip.
Water-erosion potential can be reduced with strip-till as compared to conventionally tilled systems. The alternating strips of residue that remain will slow surface water movement and will maintain high infiltration rates because of surface protection provided by residue. Wildlife also benefit from increased cover and nesting areas.
There are still many unknowns about strip-till. For example, for soils with near-surface compaction, will strip-till help by shallow ripping directly where the row will be planted?
Can strip-till improve planting conditions on fields that have been recently grazed by livestock? Are the positive yield effects seen by some researchers because of soil temperature changes, nutrient avail ability, more efficient use of precipitation or some other factor? Time will tell.
But what we do know is because of warmer soil temperatures and deep fertilizer placement, continuous corn may benefit from strip-till. Conversely, crops like soybeans, sunflower and sorghum, which are typically planted later, when the soil environment has improved, are less likely to respond to strip-till.
Every farmer operates differently. For those who see potential benefits of strip-till in their operations, a strip-till implement may offer an advantage. Many configurations are available, including ways of attaching units to existing toolbars. Strip-till is probably not going to replace all existing soil management systems, but it is a well-designed tool that can help you remain successful.
Editor's Note: This article was written in 2004 by Kent McVay, soil and water conservation specialist, Kansas State University, and by Brian Olson, K-State crops and soils specialist. This article has been edited for length and clarity.