The chisel plow is a specialized agricultural implement used for primary tillage, the first step in preparing a field for planting. It functions as a key component of conservation tillage systems, designed to minimize soil disturbance and protect the land. This tool works the soil deeply while leaving a significant amount of previous crop residue on the surface, setting the stage for improved soil health.
Defining the Chisel Plow and Its Operation
The structure of a chisel plow consists of a heavy, rigid frame supporting multiple curved shanks, typically spaced 12 to 15 inches apart. These shanks are the main working components, penetrating the soil and ending in replaceable points, shovels, or sweeps. The entire assembly is pulled by a tractor, and the depth is often adjustable, allowing the implement to work between 6 and 12 inches deep.
The mechanism of action is characterized by a lifting and shattering effect on the soil rather than the complete turning or inversion associated with a traditional moldboard plow. As the shanks are pulled through the soil, they create fissures and fracture compacted layers, loosening the earth without mixing the topsoil layer down into the subsoil. This process is highly effective at improving soil structure while minimizing the burial of surface residue. The type of point used, such as a straight spike point versus a twisted shovel, determines the degree of soil mixing and residue retention; a straight point maximizes residue retention, while a twisted point incorporates more plant material into the topsoil.
Primary Applications in Field Management
Farmers primarily use the chisel plow for deep primary tillage, often scheduling the operation in the fall after the harvest. This timing allows the winter weather cycle of freezing and thawing to naturally break down the rough soil surface left behind. The most frequent application is breaking up compacted layers, often referred to as a hardpan, created by the repeated passes of heavy machinery.
The shanks effectively rip through this dense soil layer, typically 8 to 12 inches below the surface, to alleviate compaction that restricts water infiltration and root growth. This action creates vertical channels that allow roots to penetrate deeper into the soil profile to access moisture and nutrients. The tool is also utilized for the initial incorporation of crop residues and fertilizers into the upper soil strata, preparing the field for shallower passes of secondary tillage equipment in the spring.
Key Advantages Over Traditional Tillage
The chisel plow’s design is central to its benefits, especially when compared to older methods like moldboard plowing which completely invert the soil. By leaving a significant percentage of crop residue on the soil surface (typically 30% to 75%), it greatly reduces the risk of wind and water erosion. This protective layer intercepts raindrops, slowing runoff and preventing the detachment of soil particles.
The residue provides a shading effect that conserves soil moisture by reducing the rate of evaporation from the surface. The shattered, loosened soil profile improves water infiltration, capturing precipitation more effectively and minimizing standing water in the field. Operationally, the chisel plow requires less draft force than a moldboard plow, which translates to an estimated 20% to 30% reduction in fuel consumption and allows farmers to cover a wider area more quickly.
Limitations and Considerations for Use
The shattering action of the shanks leaves the soil surface rough and cloddy, which is unsuitable for planting small seeds. As a result, a secondary tillage pass, such as with a field cultivator or disc harrow, is almost always necessary in the spring to create a fine, uniform seedbed.
The implement can face challenges when dealing with very heavy crop residue, such as corn stalks, which can accumulate and clog the shanks, slowing the operation. Compared to the complete inversion of a moldboard plow, the chisel plow is less effective at burying weed seeds and disease pathogens deep below the surface. Growers relying on a chisel plow must often use other methods for weed and pest control.