Abstract
The optimum growing temperature of an agricultural crop plant, vegetable and flower and ornamental plants, concentrates and exists in 15-25 degree C. A seasonal temperature change has strong influence on growing of agricultural products. The soil warming for plant husbandry is one of the effective promotion methods of an agricultural crop plant growing. Generally, the ridge warming is performed by warm water circulation of underground. The heavy oil is mainly used for water warming. The experimental results is shown that the soil warming for plant husbandry by geo thermal energy, which keeps 15-20 degree C through a year. The growth promoting effect is proved by the Japanese-mustard -spinach cultivation experiment by using the ground heat at an actual soil. It is clarified that the quantity of soil-warming-heat by using heat pipe.