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Introduction to the NFT System
The NFT (Nutrient Film Technique) is a high technology crop
production system, and requires both skill and experience from
its users if the best results are to be obtained.
" NFT achieves high
production and product quality through its effects on crop
nutrition and water relations and by providing its users with
additional opportunities to influence plant growth and
development in more productive ways than can be achieved in other
types of conventional culture. A thorough knowledge of crop
cultural practices and especially of environmental control is
needed, and NFT of itself will not overcome deficiencies in the
users knowledge in these areas. The prospect of changing from
conventional culture methods such as growing in soil to the high
technology NFT system is very daunting to many experienced
growers. These misgivings are usually overcome by installing a
small trial system as described in Section 3.
Best results from NFT will be obtained in greenhouses with good
environmental control systems. Soil quality and fertility is of
no consequence and NFT is suitable us in older greenhouses where
soil has been damaged by disease or mismanagement. Adequate
supplies of water are essential In New Zealand very few water
supplies are of such low quality that they cannot be used for NFT
production. The cost of operating NFT systems is increased when
water of low quality is used.
General Features of All NFT systems
Every NFT installation contains
channels of gullies in which the plants grow in a shallow film of
flowing nutrient solution. NFT gullies are usually, but not
always, folded lengths of black and white polythene (often called
Panda Film) laid on a carefully prepared sloping firm surface and
folded to make an inverted V shaped channel. The nutrient
solution flows out of the ends of the gullies into collecting
pipes and from the pipes into a sump. Pumps are used to circulate
the solution from the sump through flow mains and headers into the
gullies. Fresh water is added to the sump to replace water
evaporated by the crops. Additional nutrients are added as
nutrient stock solutions to the sump to replace nutrients
absorbed from the nutrient film by the crop. The nutrient
solution in the sump is kept within a certain range of acidity
(solution pH) and within a certain range of nutrient salts
concentrations (the solution conductivity of the above features
are common to both the NFT trial system and full scale commercial
NFT systems.
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