Each of four types of“pipe-beds”was established in the open air (Fig. 1, Table 1). After preliminary tests on various structures of beds and fertilizer concentrations, this experiment was made on the effects of structures of beds on the growth of broccoli. Broccoli seedlings were raised in a “ditch-ded”. It was also devised to make water rise by capillarity. Seeds were sown on August 4, 1967. Four seedlings were planted in each bed on August 26. Water was poured into the water-storage pipe continually to fill the capacity of 8 liters as the water level lowered to leave around 2 liters. Liquid fertilizer (20 cc of 10-5-8) was supplied into the pipe once every week.
The results are shown in Table 2 and Fig. 2. It is censidered that the C-type bed is satisfactory for most crops. For root crops the soil underneath the medium should be cultivated.
The studies are on the exploratory stage. Further studies should be made on the spacing of water-conducting pipes, the depth of plastic mulch placed in the central half of the bed, proper ingredients and amounts of fertilizer, and other things.
When these problems are solved, the method of water and fertilizer application is not only effective and efficient for plant growth and for saving labor but also not too expensive for construction and also durable.