Strip-tillage in California’s Central Valley
click image to zoomRandy Raper and Francisco Arriago, USDA ARS Soil Dynamics Laboratory, Auburn, Alabama, 2007Figure 8. Model of soil cross-section showing extent of soil-loosening when strip-tilling is done when soil is wet (yellow) or dry (green). Red indicates soil that is not affected by the strip-tillage shank. Timing of Strip-Tillage
Timing is a critical determinant of the success of strip-tillage systems. In general, strip-tillage 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. Research at the USDA Agricultural Research Service Soil Dynamics Laboratory in Auburn, Alabama, has demonstrated that a wider area of soil is loosened when dry soil is strip-tilled than when wet soil is strip-tilled, but this must be balanced by the need to provide satisfactory seeding conditions (fig. 8). Timing of the strip-tillage operations ultimately depends on the specific implement that is available, whether the strip-tiller is hooked directly to the planter, and the need to seed at a certain time in order to achieve yield goals.
Strip-tillage is most effectively accomplished when the soil in the vertical zone that is to be tilled is relatively dry, but not so dry that the strip-till implement brings up large soil clods or bends under the high resistance that can exist in very dry conditions. Conversely, strip-tillage is best done when the soil is somewhat moist, but not so wet that compacted layers are not shattered or broken up. Thus, in forage corn production systems, strip-tillage would generally be done immediately following winter small grain chopping and before pre-irrigation for corn.
Dairy Forage Production and Strip-Tillage
For strip-tillage to become a sustainable management option in dairy forage production systems, several issues must be addressed and resolved. The distance between irrigation berms that are typically used to facilitate water movement across a field and the actual size of these berms should be determined and set out in advance to permit optimal seeding and harvesting of all crops in a forage rotation. When strip-tillage and no-tillage corn seeding was first introduced into San Joaquin Valley forage fields, farmers tended to avoid planting the berm areas because they did not think it would be successful. By not planting berm areas, however, a sizeable portion of the field remains unproductive. Strip-till and no-till corn farmers now use different strategies to address this problem. Planting or strip-tilling and then planting directly over the berms can be done if existing berms are relatively shallow or low. Another approach is to reconfigure fields with relatively narrow berms that permit GPS-enabled planting and the strip-till planting directly up to the base of the berm. The narrow berm is left unplanted, but planting is done on all but the top of the berms throughout a field.