Forcing a crop of witloof chicory (Cichorium intybus L.) by using heat from the fermentation of cow manure

Abstract

This research investigated the feasibility of producing witloof chicory with heat from the fermentation of cow manure in the semi-cold and cold seasons. Chicory roots were grown in the experimental farm of Hokkaido University (Sapporo, Japan) and sorted roots were stored in a refrigerator or a snow storage chamber until the start of forcing culture. In the semi-cold season (one test, April to May 2013) and cold season (two tests, March 2014 and 2015), experiments were conducted in Yubari city, Hokkaido, in the indoor experimental facilities. In each experiment, cow's compost which was produced through a solid-liquid separator (water content; approx. 72.6%) was used as the heat source. The heat supply was by circulating antifreeze solution through heat exchangers which were installed between compost containers and forcing chambers. Temperatures of the outside and inside air, compost container, forcing chambers (soil and air) and heat exchangers were recorded. Through all experiments, compost temperature was maintained up to 30°C, and it showed potential to be used as a heat source for the chicory crop. In the semi-cold season, temperatures of forcing chambers (6.3×0.9×0.65 m) were maintained stable, and average air temperature of the forcing chamber reached 17.2°C, and marketable chicons were obtained after 22 days. In the cold season, air temperature of the forcing chamber (3×0.9×0.65 m) was maintained stable (10.6°C in 2014, 14.4°C in 2015), and marketable chicons were obtained after 15 to 19 days. The results indicated that forcing a witloof chicory crop in semi-cold and cold seasons by using heat from the fermentation of cow manure can be possible.