The adoption of no-tillage (NT) farming increased water-use efficiency and enabled cropping intensification, especially in semi-arid environments like western Kansas, by increasing soil water storage through greater retention of crop residue on the soil surface. With more residue retained in NT systems, wind and water erosion are reduced, and more organic matter accumulates in the soil. However, despite these benefits, maintaining continuous NT has become increasingly challenging due to the lack of herbicide options for difficult-to-control and herbicide-resistant (HR) weeds, as well as issues with stratification of soil pH with increasing soil acidification near the surface.
The lack of effective herbicide options to control perennial grass weeds like tumble windmillgrass, tumblegrass, and purple three-awn, as well as HR kochia and Palmer amaranth, poses some of the most significant challenges to long-term NT systems (Figure 1). With the increased costs of alternative herbicide options, increasing agricultural input costs, and reduced commodity prices, some farmers resort to tillage as a cost-effective strategy to manage weeds.
Figure 1. Purple three-awn, tumble grass, and tumble windmillgrass growing in a fallow field in Finney County. Note the nodding purple-to-red seed heads. Photo by Logan Simon, K-State Extension.
Strategic and Occasional Tillage as a Management Tactic in Long-Term No-Tillage Systems
K-State agronomists at the Western Kansas Research-Extension Centers in Hays, Garden City, and Tribune have studied strategic and occasional tillage in NT fields to manage difficult-to-control and HR weeds and evaluated impacts on crop yields and soil properties.
What is strategic tillage? Strategic tillage is defined as a one-time tillage operation in an otherwise NT cropping system to manage challenges of long-term NT (Figure 2), including difficult-to-control weeds and pH stratification. Following this strategic tillage operation, the system returns to NT. The sweep plow, a non-inversion conservation tillage implement, is the most commonly used implement for strategic tillage. Inversion-type tillage with a disk may be preferable in correcting pH stratification if needed.