Seed drill
A seed drill sows seed in evenly spaced rows at a set depth and covers it over, instead of scattering it on the surface. It is the usual way to sow cereals, oilseed rape, grass and many other crops.
How it works
Seed sits in a hopper above a metering unit, traditionally a row of fluted rollers. On older drills a land wheel drives the meter through gears, so the amount sown stays in step with forward speed; changing the gearing changes the seed rate. Each row gets its own share of seed, which falls or is carried down a tube to a coulter.
The coulter opens a narrow slot at the chosen depth. It may be a tine, a single angled disc or a pair of discs set in a V. Seed drops into the slot and a press wheel or harrow behind closes and firms it, giving good seed-to-soil contact for even germination. On air drills one central meter feeds a fan-blown airstream that carries seed to a distribution head, which splits it among the rows.
Main types
- Mechanical (gravity) drill: Each row has its own meter and seed falls down the tubes. Simple and accurate, but width is limited by the hopper length.
- Pneumatic (air) drill: A hydraulic fan blows seed from one meter to every coulter, which allows wide folding drills of 12 m or so.
- Combination drill: A drill mounted on top of a power harrow so the seedbed is made and sown in one pass.
- Cultivator drill: Discs or tines, a packer, the coulters and press wheels on one trailed frame. Vaderstad's Rapid, launched in 1991, prepares, levels, sows and firms in a single pass.
- Direct (no-till) drill: Strong coulters sow straight into stubble or cover crops without any cultivation, keeping soil structure and soil life undisturbed.
Hooking it up to a tractor
Small drills hang on the three-point linkage, either alone or on a power harrow. Larger cultivator and air drills are trailed on the drawbar and need several hydraulic services for folding, lifting, markers and the fan, plus a power supply for the control box. Power need rises steeply with the amount of cultivation built into the drill.
A short history
Seed drills are ancient: the Babylonians used simple tube drills around 1400 BC, and multi-tube iron drills appeared in China in the second century BC. In Europe a drill was patented in Venice in 1566, and in England Jethro Tull developed his horse drill in 1701. Early drills were costly and fragile, and only became common in the mid to late 1800s, when machine tools made precise metal parts cheap. Sowing in rows let farmers hoe between them and used far less seed than broadcasting by hand.
Buying and care tips
- Calibrate every time: Do a calibration test whenever you change crop or seed lot, because seed size varies. Weigh what the meter delivers and adjust.
- Check coulters: Worn discs, tips and scrapers give uneven depth. Measure disc diameter against the maker's minimum.
- Look for blockages: Check seed tubes, the distribution head and hoses for cracks and blockages, and the fan for leaks.
- Clean out: Empty and clean the hopper and meter after use so seed and fertiliser residue do not attract damp, corrosion or vermin.
Questions people ask
What is the difference between a seed drill and a precision drill?
A seed drill sows a steady stream of seed into each row, ideal for cereals. A precision drill or planter places single seeds at an exact spacing, used for maize, sugar beet and similar crops.
What is a combination drill?
A drill mounted on a power harrow, so the soil is worked into a seedbed and sown in one trip across the field.
What is direct drilling?
Sowing straight into the previous crop's stubble, or a cover crop, without ploughing or cultivating first.
Related equipment
Sources
- Seed drill (Wikipedia)
- Rapid celebrates 30 years (Vaderstad)
- Pronto 3-4 DC disc seed drill (Horsch)
- Power harrows HR 104-1004 (Kuhn)
Last checked 2026-11-01