Fundamental Studies on Land Improvement in an Orchard Surrounded with the Paddy Field

为了给今后的灌溉、土地改良和果园复垦计划的制定提供必要的基础数据，1990 ~ 1993年，采用水箱模型法，对稻田围成的梨、葡萄、樱桃和石榴果园根系发育、土壤水分波动、地下水位和土壤水分平衡的实际情况进行了调查。所得结果如下。1.葡萄、梨和柿子的根在顶部30 cm层中被发现占总根重量的约93%至约99%。2.果园10 cm、20 cm、30 cm、50 cm和70 cm土层的土壤水分吸力在白天呈上升趋势，夜间逐渐下降。据认为，这些波动直接关系到根系的深度分布，吸收水分在每个深度。3.落叶果树的冠根比分别为1.6-1.7（葡萄）、1.4-2.0（柿）和2.7-3.1（梨）。4.果园的灌溉设施是必不可少的。5.采用水箱模型法和水量平衡法对柿果园土壤水分平衡进行了估算。

With a view of obtaining basic data mecessary for making a future plan of irrigation, land improvement project and reclamation of an orchard, the actual conditions of root development, soil moisture fluctuation, ground-water level and soil moisture balance by the tank model method in an orchard (Pear, Grape, Cherry and Persimmon) surrounded with the paddy field, were investigated from 1990 to 1993. The results obtained are as follows. 1. The roots of grape, pear and persimmon were found in the top 30 cm layr from about 93 % to about 99 % of the total root weight. 2. Soil moisture suction at a depth of 10 cm, 20 cm, 30 cm, 50 cm and 70 cm in an orchard rose during the day and decreased gradually during the night. It is considered that these fluctuations are directly related to the depth distribution of roots which absorb water at each depth. 3. The top-root ratio of deciduous fruit trees was 1.6-1.7 (grape), 1.4-2.0 (persimmon) and 2.7-3.1 (pear) respectively. 4. The irrigation facilities for irrigation in a pear orchard is necessary. 5. The estimation of soil moisture balance in the persimmon orchard was made by means of the tank model method as well as the water balance method.