A chisel plow is a tillage machine used to loosen compacted soil without completely turning it over. It is pulled by a tractor and uses strong curved shanks to break the soil below the surface. This matters because compacted soil can block root growth, reduce water infiltration, and lower crop yields.
Compared with a moldboard plow, a chisel plow leaves more crop residue on the surface, which helps reduce erosion.
Key Facts
- Drawbar power is the useful pulling power delivered to the implement: P = Fv.
- Draft force is the horizontal pulling force needed to move the chisel plow through soil.
- Typical chisel plowing depth is about 20 cm to 40 cm, depending on soil conditions and crop needs.
- A wider plow or deeper tillage usually increases draft force and fuel use.
- Soil fracture zones form around each shank and can overlap when shank spacing is chosen correctly.
- Leaving residue on the surface protects soil from raindrop impact, runoff, and wind erosion.
Vocabulary
- Chisel plow
- A tillage implement with strong shanks that loosen soil deeply while leaving much of the surface residue in place.
- Shank
- A curved or straight metal arm on a chisel plow that penetrates the soil and creates fractures as it moves forward.
- Draft force
- The horizontal force required to pull an agricultural implement through the soil.
- Soil compaction
- The squeezing together of soil particles, which reduces pore space and can limit air, water, and root movement.
- Residue cover
- The layer of crop stems, leaves, and roots left on the soil surface after harvest or tillage.
Common Mistakes to Avoid
- Assuming deeper is always better, which is wrong because excessive depth can waste fuel, increase wear, and disturb soil that does not need loosening.
- Ignoring soil moisture, which is wrong because soil that is too wet may smear instead of fracture and soil that is too dry may require much more draft force.
- Using shanks that are spaced too far apart, which is wrong because the fracture zones may not overlap and compacted strips can remain between passes.
- Confusing chisel plowing with full inversion plowing, which is wrong because a chisel plow loosens and fractures soil but does not completely flip the soil layer over.
Practice Questions
- 1 A tractor pulls a chisel plow with a draft force of 18,000 N at a speed of 2.0 m/s. What drawbar power is required in watts and kilowatts?
- 2 A chisel plow is set to work 0.30 m deep and has 7 shanks spaced 0.40 m apart. Estimate the total working width using the distance across the shanks from first to last plus one spacing.
- 3 A field has a hard compacted layer at 25 cm depth and has crop residue on the surface. Explain why a farmer might choose a chisel plow instead of a moldboard plow.