畑地灌漑に関する基礎研究 (第III及IV報) : 甘蔗の吸水特性並びに灌漑用水量算出式に就いて
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The author studied the water absorption characteristic of sugar cane plant from various angles for many years. The results are summarized here introducing a formula for calculating the amount of water required in irrigation of the plant. The results of measurement with autoirrigators or tensiometers are summarized as follows. 1) The cane plant proved itself to have two processes, active and passive, in water absorption. The passive absorption was larger in water amount than the active. Therefore, the top size of the cane plant affected remarkably the absorption. To certain extent, the water absorption in the cane plant inreased porportionally with its stem length. 2) As the water absorption was largely influenced by environmental conditions, distinct diurnal changes in water absorption were observed as shown in Fig. 1. The data in Fig. 1 were obtained by automatic recorders, which were designed by the author. On fine days, the diurnal variation in absorption showed one maximum point, the curve running nearly parallel with that of evaporation. 3) Such paralellism between water absorption and evaporation was also observed on a solareclipse day, Sept. 21,1941 (TAMAI, 1943). 4) The same paralellism was also observed on each of other normal cases. The correlation between those two phenomena was high, r=0.74〜0.92 5) The relation between water absorption and length-growth over the whole growing season (14 months) was studied. Absorption intensity increased with the length growth of the plant to some extent (Fig. 2). It gradually decreased, however from autumn to the year end. The amount absorbed during July to September was one-half of that for the whole growing season. 6) The relation among the growth stages concerning the water absorbing capacity of the root per unit area of leaf was, as follows: young plant <middle aged plant> old plant; though the differences among them were not so large. 7) From the experiments on the water absorption above mentioned, following estimates were obtained. Average amount of water absorbed per day per stem =291〜300cc Water requirement =242〜287cc These values are nearly the same as those by other investigators. Calculating from these data, the amount of water required in sugar cane fields, which produce 150000 kin of canes per hectare, may be 700〜850mm in depth during the whole growing season. As a general principle, the amount of water absorbed by the cane plant may be calculated from the following two factors; (1) the size of plant (cane yield) (2) the evaporation from water surface (II) A formula for calculating the water amount required in irrigation of sugar cane. A formula was deduced from the results above mentioned and other data (TAMAI and BABA, 1942) as follows. The water amount for the cane irrigation, [numerical formula] Where E・・・Evaporation observed by means of evporating dishes during the growing season of sugar cane plant. a・・・Absorbing coefficient concerned in the cane yield; cane yield・・・50000→200000 kin per hect., (kin=0.6kg) a・・・・・・・・・0.5→2.0 b・・・Evaporation coefficient concerned in the physical property of soil; gravelly sand→clay, b・・・0.3→1.0 c・・・Percolation coefficient concerned in the physical property of soil; gravelly sand→clay, c・・・0.3→1.0 The values 0.36, 0.5, 0.25 in the formula are constant for the cane field producing canes of 100000 kin per hectare. Using this formula, the author could calculated nearly reasonable values of the amount of irrgating water at three places under different weather conditions (Table 1).
- 日本作物学会の論文
- 1955-07-20