2. Devices of potato planters

Potato planters may be mounted or trailed. Most of them are fully automatic and, depend­ing on model, plant between two and eight rows. Planters for de-stoned beds plant from two to six rows in each bed and a typical twelve-row machine will, in a single pass, plant four rows of potatoes in three adjacent beds. The planting mechanism may be driven by a hydraulic motor or more usually by the land wheels. Hopper capacities vary from 500 kg on a two-row planter up to 5 tonnes on big trailed machines. Chitted seed planters carry up to 1.25 tonnes of potatoes. Wide potato planters are folded hydraulically for transport.

A coulter makes a furrow for each row being planted, while a feed mechanism carries pota­toes from the hopper and places them in the ground at regular intervals. Ridging bodies or angled concave discs cover the potatoes with soil to complete the operation. Some planters have a ridge topping bar to leave flat-topped ridges.

Farmers who grow a few potatoes may use a hand fed planter which requires an operator for each row. Potatoes are either dropped down a tube into a furrow or placed in land wheel driven rotating cups which drop the tubers into the soil at regular intervals. Chitted (sprouted) and unchitted seed can be planted with hand fed planters.

Figure 18.6 Cup feed potato planters for chitted and for unchitted seed. (Cramer)

2.1. Cup feed planters

The standard continental European potato planter singles the tubers by vertical belts with cups, which move upwards through the supply (Fig. 18.6). Skips and multiples can occur. The larger the potatoes in comparison to the cups and the higher the belt speed, the higher the share of skips and the lower the share of multiples is. Therefore it is possible to use the machines in such a way that either skips or multiples dominate. In the past, the machines were operated with skips and, for practical purposes, without multiples. The cups with skips were sensed and provided with a tuber from a compensating magazine. The present-day method is opposite the planters are operated in such a way that mainly multiples instead of skips are attained. These multiples are removed by shaking the belt (Fig. 18.6).

Automatic cup-feed planters have land-wheel or hydraulic-motor driven belts with a series of cups to carry seed potatoes from the hopper to the ground.

Examples of two-row mounted automatic cup-feed planters, shown in Figure 18.6, are suitable for unchitted and chitted seed. They have land-wheel driven endless belts with cups which collect single potatoes from the hopper and places them at regular intervals in a furrow made by a coulter. The potatoes are covered by a pair of concave discs.

A two-row cup-feed planter with a 1.25 tonne hopper used on level ground requires a tractor of 65 kW (85 hp). A six-row trailed planter, with a 4 tonne hopper and an output of up to 40 acres a dav in prepared beds, will need a 115 kW (150 hp) tractor.

Most cup-feed planters can be used with dif­ferent sized cups to suit various sizes of seed potato. Spacing of the seed in the rows will depend on the planter and type of planting, and can vary between 100 mm and 600 mm or more. The narrower spacings are used when planting four, five or six rows across each bed for the production of very small tubers for specialist markets.

Some planters have a control unit in the tractor cab which is used to select the correct cup-belt drive speed to plant the crop at the required spacing in the row. The control unit can also be linked to electronic sensors that con­stantly monitor, and when necessary change, the speed of cup belts to compensate for varia­tions in forward speed and maintain the required tuber spacing.