ENERGY INPUT IN TWO NFT SYSTEMS FOR TOMATOES
The heated NFT tomato crop picked 19 per cent more heavily than that grown in border soil; the cash return was 31 per cent better in 1979. Considering, however, that electrical heating of the nutrient cost BF 40 per plant in 1979 the neat difference in cost return must be reduced to 22 per cent compared with soil-grown plants.
By temporary lowering the aerial temperature it was possible to reduce the consumption of heating oil by 9 per cent but the consumption of electricity was 20 per cent higher. Taking the cost of energy into account cash return of the heated NFT crop was actually 32 per cent better than that of cold NFT plants.
It appeared further that to cover the cost of energy in 1979, 3 trusses were needed of heated NFT plants and of soil grown plants as against 4 of cold NFT plants.