(J. of the Society of Agricultural Structures, Japan, 40(1), 57-65, 2009)
Development of Automatic Irrigation Systems for Netted Melon Cultivation in Greenhouse
Using Fuzzy Controller

Kazuhiro NAKANO, Takako AIDA, Digui YANG, Shintaroh OHASHI and Qingyun CHEN

Summary

The price of netted melon varies with its quality in Japan. It is very difficult to control the soil moisture precisely in various growing stages of melon cultivation, because irrigation management in a greenhouse needs know-how and judgment of practical farmer. Irrigation management has a very important influence on the quality of melon; especially it is more difficult in case of sandy soil.In this study, a Fuzzy decision-making irrigation system, which was developed using the know-how extracted from a practical farmer, was compared with an On-off control system and a conventional manual irrigation by a practical farmer. The experimental crop was netted melon which cultivated in a greenhouse with sandy soil. The irrigation amount was controlled by the target ranges of various stages of netted melon. In the Fuzzy control area, the variation of soil moisture content was predicted by Fuzzy rules based on various climate values, such as solar radiation, soil moisture, inside temperature of greenhouse and atmospheric pressure. In the On-off control area, the only irrigation index was that whether soil moisture was lower than the lowest target range or not. Compared to the Manual irrigation by a farmer, the water-saving coefficients in the Fuzzy control and the On-off control were 48.7% and 16.5%, respectively. The qualities of melon cultivated in the Fuzzy control, sugar content and grade of exterior appearances, were almost the same as that of the On-off control or Manual irrigation. As the result, the Fuzzy irrigation system for netted melon cultivation in greenhouse is very valuable, and the multiple farmers can save working hour, labor and irrigation water in the busy summer season.



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