ELECTRICAL FORCING OF BELGIAN ENDIVE (CHICORY - WITLOOF)

From an economic as well as from a social point of view the cultivation of Belgian endive (witloof) is of the utmost importance for Belgium. From a social point of view, because some 7,000 families earn their livelihood from it, and from an economic point of view, because there is an annual export of more than 40,000 tons, representing a value of more than 500 million Belgian francs (4,000,000 pounds sterling). This crop, however, has a drawback. It is a labour-intensive crop, because the number of hours of manual labour represents 60% of the cost of production. As there are in Belgium some 8,000 ha (20,000 acres) of Witloof, with a production of more than 90,000 tons (1,800,000 cwts), it can easily be realized how many hours are spent on it.

Despite the labour-intensive nature of this crop, there is a yearly increase in Witloof cultivation.

There are two methods of Witloof production: cultivation in the field and forcing at home.

In field production, where sowing, thinning out and digging up are the most important activities, much labour has already been saved by the design of ever newer and more perfect machines.

Consequently it is the forcing process that makes heavy demands on labour. The layering, control of the heating, harvesting, cleaning and packing of the Witloof take a lot of time.

Much research has been done on the control of the heating system.

The layering and removal of the roots is still done by hand; it is very difficult to have this done by machines as it requires the utmost precision. The cleaning of Witloof however, is being done more and more by cooperative firms, where there are several large washing machines. In this way the Witloof is quickly ready for sale.

The classical heating system is still the thermosiphon system: i.e. by means of a stove water is brought to boiling point and it flows into a network of pipes that has been spread around and among the roots. The heat encourages the development of a great many roots with a fibrous structure on which the Witloof will grow.

The electrical system is based on the preceding method, but here heat is generated under the roots. Resistance wires are linked with a low-voltage transformer (lower than 26 volt). For a layer of Witloof, the dimensions are usually as follows: length 7.10 m (7.8 yards), width 1.90 m (2.1 yards).

The heating arrangement consists of 2 circuits, the first circuit being spread out in the border area of the Witloof layer (±5.30 m2 = 6.4 sq yards), and the second in the inner area (±8.20 m2 = 9.8 sq yards).