Application of mixed straw and biochar meets plant demand of carbon dioxide and increases soil carbon storage in sunken solar greenhouse vegetable production
Yiming Zhao, Shan Lin, Yanni Liu, Guoyuan Li, Jinggou Wang, Klaus Butterbach‐Bahl
Abstract
Abstract Solar vegetable greenhouse soils show low soil organic carbon content and thus also low rates of soil respiration. Processing vegetable residues to biochar and mixing biochar with maize straw might improve soil respiration and increase soil organic carbon stocks, while preventing the spread of soil‐borne diseases carried by vegetable residues. In an incubation experiment, we tested how additions of maize straw (S) and biochar (B) added in varying ratios (100S, 75S25B, 50S50B, 25S75B, 100B and 0S0B (control)) affect soil respiration and fraction of added C remaining in soil. Daily CO 2 emissions were measured over 60 days incubation, the natural abundance of 13 C in soil and in the added biochar and maize straw were analysed. Our result shows that (a) soil CO 2 emissions were significantly increased compared to soil without the straw additions, while addition of biochar only decreased soil respiration; (b) cumulative CO 2 emissions decreased with increasing ratio of added biochar to maize straw; (c) the abundance of soil 13 C was significant positively correlated with cumulative CO 2 emissions, and thus with the ratio of straw addition. Our results indicate that incorporation of maize straw in greenhouse soils is a meaningful measure to increase soil respiration and to facilitate greenhouse atmosphere CO 2 limitation while producing vegetables. On the other hand, additions of biochar from vegetable residues will increase soil organic carbon concentration. Therefore, the simultaneous application of maize straw and biochar obtained from vegetable residues is an effective option to maintain essential soil functions for vegetable production in sunken solar greenhouses.