Snow vault becomes chicory root storage facility and supplies coolant for chicon production in summer

Chicory (Cichorium intybus L.) roots are stored at freezing temperature and chicon (edible part) are produced in a temperature-controlled dark room by planting the stored roots throughout the year. For the establishment of chicon production with natural energy, a snow vault was used for storage of the chicory roots and providing cooling in the summer. In the experimental location, Yubari City in Hokkaido, the heavy snow region of northern Japan, snow was stored in an underground vault. Chicory roots were stored in the snow vault and a refrigerator (4-5°C) from late in December 2012 and planted in the culture bed (length 3.6 m, width 0.9 m and height 0.6 m) after storage for 1, 3, 5 and 6 months, respectively. The temperature in the snow vault was 1-2°C. Most of the roots stored in the snow vault and the refrigerator until May survived, however the survival ratios for 6 month storage were 80% in the snow vault and nearly 0% in the refrigerator in late June. Chicory yield had a tendency to decrease as the storage period increased, especially in the planting of refrigerator-stored root after 3 months. The roots stored in the snow vault for up to 5 months grew marketable chicons. The bottom of the snow vault was fitted with a pipe through which an antifreeze solution was circulated. The pipe was connected to the bottom and wall of culture beds for cooling the soil directly. The top, bottom and walls of the culture beds were thermally insulated. The environment in the experimental room was conditioned by circulating air through a pipe, 25 m long, buried 2 m underground. This enabled the temperature of the experiment room to be stabilized at around 20°C even in mid-summer. The snow cooling system with the circulation of the cold antifreeze solution controlled the culture bed temperature to 15°C, which is suitable for chicon production.