|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1995 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1994 : ¥1,300,000 (Direct Cost : ¥1,300,000)
The objective of this study was to investigate the actual situation of greenhouse water use and its implications for irrigation planning. To achieve this actual water use in both the greenhouse and the immediate surrounding uplands fields were examined. The micrometeorological conditions and the soil moisture content within and outside the greenhouse were measured, and from the micrometeorological data the estimation of the water requirements of some plants were estimated.
The experiments conducted are as follows :
1) The micrometeorological conditions within and outside the greenhouse at Soja City area (i.e.Egg Plant), Okayama Prefecture, and Daiei Town area (i.e.water melon), Tottori Prefecture, were measured. Also, the soil moisture content and irrigation amount within the greenhouses was measured.
In comparing the results the meteorological measurements, the fact that the temperature was high with solar radiation being low within the greenhouse was confirmed. Using meteorological data
of the greenhouse the Penman equation was used to estimate evapotranspiration of the egg plant and water melon. The results obtained compared fairly well with evapotranspiration estimated from the water balance of the greenhouse. It was concluded that the Penman equation can be used to estimate water use in a greenhouse with a fair degree of accuracy.
2) In this study micrometeorological data was collected at Tohaku town (i.e.lawn field), Tottori Prefecture, and Daiei Town (i.e.Broccoli field). Also, soil moisture content and rainfall amount were measured.
3) The actual water use situation in the Tohaku Irrigation Project district (i.e.Tohaku town and Daiei town, Tottori Prefecture) was investigated. This involved a comparison between the hourly discharge from farm ponds in the area and the water use at the farm level. Also, a questionnaire was prepared to investigate water use at the farm level in relation to the kind of crop.
The investigations revealed that the peak discharge from the farm ponds was in the morning and evening. This, however, did not interfere with the operation and maintenance of the farm ponds. Also, the amount of discharge from the farm pond fluctuated with rainfall amount in which more water was used during long, clear, dry days. The time, amount, and method of water application also differed with respect to the kind of crop, and with respect to whether crops were grown in greenhouses or in the open field. Less