CO2 Utilization Strategy for Sustainable Cultivation of Mushrooms and Lettuces

Abstract

Mushroom cultivation generates a large amount of CO2 that can be used sustainably. The objective of this study was to use actual cultivation and simulation to find a sustainable cultivation method that uses the CO2 generated by king oyster mushrooms for the production of romaine lettuces. A closed cultivation system consisting of one mushroom chamber, three lettuce chambers, and one gas-mixing chamber was used. Two cultivation conditions, non-continuous and continuous, were analyzed. The non-continuous system cultivated 15 lettuces and 12 mushroom bottles at a time every 25 and 16 days, respectively. The continuous system cultivated three lettuces and mushroom bottles every five and four days, respectively, so that each chamber contained mushrooms or lettuces at each growth stage. The CO2 concentrations in the lettuce and mushroom chambers were stably maintained above 1000 μmol∙mol−1 and below 2000 μmol∙mol−1 in the continuous system. Mathematical models were developed to analyze the CO2 concentration in each chamber. The shoot dry weight of lettuces grown in the mixed cultivation were 48.0%, 21.9%, 19.7%, and 18.1% at 10, 15, 20, and 25 days after transplanting, respectively, higher than those in the lettuce-only cultivation. Compared to mushroom-only cultivation, mixed cultivation reduced the accumulated CO2 emissions into the air by 80.6%. Thus, using CO2 from mushrooms to cultivate lettuce in a continuous cultivation system could reduce CO2 emissions into the air and enable mixed cultivation of mushrooms and lettuces, achieving sustainable agriculture.