Stone Picker

A stone picker is a tractor-towed conveyor implement that sieves the topsoil with digging teeth, lifts loose stones onto a chain or roller conveyor and discharges them into a hydraulic-lift hopper, leaving the sieved soil behind. It is used to bring rocky and stony fields under regular mechanised cultivation, where loose stones would otherwise damage rotavator blades, baler pick-ups and combine cutter-bars.

Function

A set of front-mounted rake teeth penetrates the topsoil to a working depth of a few centimetres, lifting stones and clods. A chain conveyor or rotating roller carries the lifted material upward; smaller soil and fine material falls back through gaps, while stones above the gap size are retained and discharged into the hopper. When the hopper is full, the hydraulic lift tips it into a trailer for off-site disposal.

Design and specifications

The implement is driven by a PTO with a slip clutch and requires a 35-60 HP tractor depending on width. Leading manufacturers include Highline (NT78), Kongskilde, Kivi-Pekka, Degelman and Schulte. A typical conveyor is sized to lift stones in the 1-15 kg range, although larger units handle much heavier rocks.

Operation

The implement is operated in passes across the field after primary cultivation, often with a second tractor running alongside to receive the dumped hopper load. Coverage rate depends on stone density: 1 acre takes around 2.5-3.5 hours in moderately stony soils. After clearance, the field can be cultivated with a Rotavator or seeded with a Seed Drill without risk of damage.

Subsidy and adoption

The stone picker is included in SMAM land-preparation implement categories in stony-soil states. In Indian conditions, where new ownership is rare because of cost, the implement is most commonly operated as a custom-hire service.

References

NT78 Rock Picker. Highline Manufacturing.
Stone Picker. Wikipedia.