アナログ式蒸発散計を用いた育苗用自動灌水装置の試作

抄録

An automatic ebb-and-flow watering system with an analog evapotranspiration meter for transplant production was developed and used for cucumber plug seedlings. The plug sheets consist of plug seedlings, soil mix, and a tray that were placed on a bench with an ebb-and-flow system. The evapotranspiration of a plug sheet located in the center of the bench was measured with an analog evapotranspiration meter using a spring balance equipped with movable pointers for the maximum weight and the weight to start the watering. The evapotranspiration of the plug sheet was estimated with the difference between the pointers for the maximum weight and the current weight. When the pointer for the current weight reached the pointer for the weight to start watering, then a switch to start watering was turned on and all the plug sheets were watered from below, and the weight of the plug sheet increased. When the maximum weight of the plug sheet increased with the seedling growth after watering, the pointers for the maximum weight and the weight to start watering moved simultaneously due to the current weight pointer. Although some sort of mechanical improvement was required to reduce operating errors of the pointers, the watering system controlled the soil-mix moisture in the plug tray in an almost proper range for growth of the plug seedlings during the culture period.