ENERGY SAVING AND PROTECTED CULTIVATION IN JAPAN

At that time we had only glasshouses of nearly 100 hectares, excepting the frames of 470 hectares for growing vegetables. After that the increases in area under plastic film was fantastic, from essentially none in 1954 to nearly 69000 hectares in 1973 when the oil crisis occurred. Of this area, 48500 hectare was for low tunnels of temporary structure and the rest, 20100 hectare was for plastic-houses. Within the total area of under plastic, 96% was used for vegatables including melons and strawberries. Almost all the plastic-houses and one third of low tunnels are covered with PVC.

Since the number of greenhouse vegetable growers was about 160000, in 1973, the average greenhouse holding did not exceed 0.11 hectares (0.27 acres). Such a small size of holding is a significant feature of protected horticulture in this country. The figure implies that a greater part of growers did not specialize in greenhouse production, and this situation is the most important factor to understand the present and future of protected cultivation in this country.

We consumed during the year of 1972–1973 about 105 million kilolitres of fuel for greenhouse heating and 13 million tons of plastic for coverings. Since in order to make this amount of plastic 294 million tons of petroleum is needed as a raw material, total amount of petroleum used for protected production accumulated up to about 400 million tons per year. Of course, almost of all was imported, mostly from the Middle East.

In October 1973 after the oil producing countries declared the cut down of oil export as well as price-raising, fuel and plastic films for agriculture rapidly disappeared in the market of this country. Greenhouse growers just going to prepare for winter cropping were completely at a loss.

The government, who had fear for vegetable food panic, gave to oil sellers the instruction of supplying fuel to growers in the same quantity as last year, so that a greater part of growers could by any means coutinue greenhouse heating under the situation of soaring prices. But, not a few, who had been buying oil from the outsiders of the farm cooperative, were obliged to reduce their cropping area or give up growing on the way owing to the shortage of heating oil.

In spite of causing such difficulties at that time and considerable damages, the oil crisis had, from the long-range viewpoint, rather desirable effects on protected cultivation in this country; the greatest one is that the oil crises acted as a brake on the trend of too much increase in greenhouse area which would cause a slump of price due to overproduction. The second is that it remarkably stimulated growers to manage their greenhouses more carefully, especially on the control of interior climate. In conclusion, it might be said that greenhouse growers in this country have skillfully

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