PROTECTED CROPPING TECHNIQUES

CHOICE OF SITE

Important points to consider in choosing a site would be:

Light

Although it may seen obvious, glasshouses should be erected where trees or buildings will not shade them at any time of the year. Maximum light intensity is the paramount aim.

Shelter

As wind speeds increase so does the heat loss. For example, when wind speed increases from nought to fifteen miles per hour, the heat loss is doubled. Any shelter which can be provided will help to reduce and control the heating costs. This is often achieved by planting wind-break hedges around nurseries, as long as these are of sufficient distance away not to interfere with light levels.

Many nurseries are situated near the coast because of the good light conditions, this also brings exposure to winds therefore a balance has to be achieved again with the use of wind-breaks or other protection such as double cladding and double-skinned houses. Rate of heat loss is affected more by wind speed than the outside temperature. A good wind-break of 50:50 permeability gives protection downwind for ten times its height, reduces the wind speed by 30% which means that 10% fuel saving is made over the year, or even more is possible on very exposed sites. Natural wind-breaks using a mixture of conifers and deciduous trees will cost far less than artificial materials such as Paraweb, but will take longer to become effective.

Aspect

A fairly level site is the most suitable because when a heating system is used heat can be distributed more evenly throughout the houses.

Water supplies

An adequate supply of clean water is essential for any commercial nursery either from the mains or a special borehole. When using mains water it is required under law that the supply is broken with a break-tank or reservoir. You are not permitted to take water direct from the mains because of chemicals or soil being drawn back into the drinking water system.

For estimating water requirements about 5,600 cubic metres of water would be needed for one hectare of a tomato crop per season. That is 500,000 gallons per acre.

In northern Europe, in the seventeenth century many orangeries were built in the great gardens of wealthy land owners. By the early 18th century it was fashionable to grow exotic plants and fruits from abroad in conservatories, an example of which can be seen in the Great Conservatory of 1840 at Chatsworth, Derbyshire.

The start of commercial glasshouse growing on a large scale was started about 1860-1870 in the Worthing area of Sussex when tomatoes and grapes were grown especially for the London market. From this developed the extensive market garden and glasshouse industry to the north of London in the Lee Valley. The objective of the commercial grower was then and still is, to provide a near optimum environment for the crop, to achieve profitable crop production.

Sorry, comments are closed for this post.