A tine harrow is an agricultural machine that uses many narrow metal tines to scratch, stir, and level the upper layer of soil. Farmers use it after primary tillage to break small clods, spread residue, uproot young weeds, and prepare a smoother seedbed. It matters because seed placement, soil contact, water infiltration, and early crop growth all depend on the condition of the top few centimeters of soil.
The machine looks simple, but its performance depends on force, geometry, speed, and soil behavior.
Key Facts
- Draft force is the pulling force needed to move the harrow through soil.
- Work rate can be estimated by A = wv, where A is area per time, w is working width, and v is field speed.
- Soil disturbance generally increases when tine angle, tine depth, or travel speed increases.
- Pressure on each tine can be estimated by P = F/A, where F is contact force and A is contact area.
- Field capacity in hectares per hour can be estimated by C = wv/10 when w is in meters and v is in km/h.
- Power needed for pulling can be estimated by P = Fv, where F is draft force and v is speed in m/s.
Vocabulary
- Tine
- A tine is a narrow metal tooth or spring that penetrates and loosens the soil as the harrow moves.
- Harrow
- A harrow is a farm implement used to break up, level, or stir the surface layer of soil.
- Draft force
- Draft force is the horizontal pulling force required to move an implement through soil.
- Seedbed
- A seedbed is the prepared upper soil layer where seeds are placed for germination.
- Field capacity
- Field capacity is the rate at which a machine can cover land during field operation.
Common Mistakes to Avoid
- Confusing tine harrows with plows is wrong because tine harrows mainly work the shallow surface layer, while plows cut and invert deeper soil.
- Ignoring tine depth is wrong because even a small change in depth can greatly change draft force, soil disturbance, and seedbed quality.
- Using tractor speed without units is wrong because calculations for work rate and power require consistent units such as meters per second or kilometers per hour.
- Assuming more soil disturbance is always better is wrong because excessive stirring can dry the seedbed, bury crop residue too deeply, or damage young plants.
Practice Questions
- 1 A tine harrow has a working width of 6 m and travels at 8 km/h. Using C = wv/10, what is its ideal field capacity in hectares per hour?
- 2 A tractor pulls a tine harrow with a draft force of 4500 N at a speed of 2.0 m/s. Using P = Fv, what pulling power is required in watts and kilowatts?
- 3 A farmer notices that the harrow is leaving ridges and pulling up too much moist soil. Explain two adjustments that could reduce soil disturbance while still leveling the seedbed.