抄録
In order to study the water consumption of crops as the fundamental knowledge of irrigation, it is desirable to record the consumptive absorption rate automatically not in each individual plant but under community conditions. As the automatic water consumption recorders designed in the past were of automatic balance types, material plants were limited in their weight and also in number, usually only one or a small number of plants having been used. Therefore, it was hitherto impossible to record the variation of water consumption of field crops under community conditions continuously. TAMAI (1956), one of the authors, introduced the automatic water absorption recorder for field crops (Fig. 3) the design of which was based on a different principle from that of BRIGGS & SHANTZ (1915) and STEINBERG (1930). This recorder was one of the micro-automatic recorders for individual plants and could not be used for plant community. The authors newly devised another type of recorder, which is fit for the use of a group of a considerable number of plants. In the present paper, the construction of the new type recorder and some results obtained by using it will be stated. For the purpose of determining water absorption rate of crops under community conditions, many porous cups for auto-irrigation were connected with each other as shown in Fig. 1, and they were placed on the bench. Soil was piled up on the bench to bury the porous cups, then crops were planted in the soil, and the soil surface was covered with vinyl cloth. The amount of water absorbed by crops could be known by measuring the amount of lost water in the reservoir (R). Furthermore, the automatic recorder (recording flowmeter), as shown in Fig. 2, was provided between the porous cups (P) and the reservoir (R) so that the water absorption of crops could be recorded continuously by it. This recording flowmeter is composed of three main parts: (1) A lever (L) equipped with a water tank (T); (2) Electric valves (V1, V2) which are worked by electric magnets (M1, M2) ; (3) A part composed of a recording drum (D), a electric magnet (M3) and a recording pen (R. P.). The water tank (T) is connected with the reservoir (R) and the porous cups (P), which supply water to crops, through the two valves (V1 and V2) respectively. Suppose a difinite amount of water in the tank is spent by the crops, the lever inclines to the left because the right side of the lever becomes light. Then a balancing ball (B. B.) rolls on the lever from the center to the left and accelerates the touching of a contact point (K1). If the contact point touches, then the electric magnet (M1) acts, the valve (V1) opens, and water flows down from the reservoir (R) into the tank (T). When the amount of flowing water becomes equal to the amount of water spent by the crops, the lever inclines to the right, and the balancing ball on the lever rolls back to the center, accelerating the touch of another contact point (K2). If the contact point (K2) touches, the electric magnet (M2) acts, the valve (V2) opens, the valve (V1) closes, and the flowing water stops. Here the water in the tank is again absorbed by the crops. Simultaneously with the action of the magnet (M2), the electric magnet (M3) acts and a line is drawn with the recording pen (R. P.) on the drum (D). Thus, the absorption of water, the supply of water and the recording of lines being repeated, the water absorption of crops is recorded on the drum with the density of lines. Contact points (K3 and K4) were especially provided to use electricity instantaneously. Though lines were drawn at each time when 50 cc of water was absorbed, the volume of water absorbed at a time is adjustable by changing the size of the balancing ball (B. B. [the rest omitted]
