Chapter 17

Soil Management for Field Crops

Strip-Till

Strip-till is increasingly common and often viewed as a stepping stone to conservation tillage. With strip-till only the narrow strips into which the crop is sown are cultivated to 8 to 16 inches (3–6cm) depth leaving the strips in between undisturbed. Often, fertilizer is injected into the tilled area during the strip-tilling operation. The tilled strips correspond to planter row widths of the next crop, and seeds are planted directly into the tilled strips the following spring.

Benefits and Disadvantages of Strip-Till

Strip-till provides the benefits of both no-till and conventional till systems. Maintenance of interrow residue helps to provide the benefits of a no-till system, while the uncovered soil near the seed row reduces the negative effects of cold, wet soils often found in no-till. The advantages of strip-till over no-till are thus most likely to be seen in cold, wet springs. Strip-till does conserve more soil moisture compared to conventional tillage systems. However, in some cases, strip-till may reduce soil moisture compared to no-till. Compared to no-till, strip-till provides conventional tillage-like planting conditions in the berm that is created, and when performed in the fall, provides a warmer, better drained seedbed to plant.

Timing of Strip-Till

Timing is a critical determinant of the success of strip-till systems. In general, strip-till is most effectively performed when the soil is dry enough to allow shattering of the subsoil profile, but not so dry as to produce large surface clods of soil that do not permit even and consistent seeding. Conversely, strip-till is best done when the soil is somewhat moist, but not so wet that compacted layers are not shattered or broken up. Strip-till often takes place in the fall, giving the strips time to mellow over the winter, followed by spring planting. Fall tillage allows time for the soil in the berm to smooth during the winter and warm as soon as the weather allows in the spring before crop planting.

Placement of Seed

As outlined previously, one of the primary purposes of strip-till is to create a tilled strip in which seed will be planted in the spring. Thus, there is a desire to stay on this tilled strip when planting. Planting takes place as close as possible to the center of the berm, which has usually “melted down” by spring to be little higher than the soil between the rows. Traditional planters can be used to plant into the tilled strips. Success of this system depends on the ability to plant directly on top of the tilled strip where the fertilizer was placed.

Deep Zone-Tillage

Deep zone-tillage, one type of reduced tillage, can help counter the effects of conventional tillage. Deep zone-tillage, also known as vertical-tillage, is one of the more promising and versatile methods of reduced tillage and can help farmers reverse the ill effects of years of excessive tillage on their soils. Deep zone-tillage is similar to strip-till in that it relies on the residue of a cover crop to protect the soil surface and help improve soil health over time. However, unlike strip-till, deep zone-tillage uses a subsoiling shank to break up the plow pan. Crop roots grow deep through the slit made by the shank rather than just spreading out in the top few inches of soil above the plow pan.

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