Maize root‐induced change in soil organic carbon pools

Quantification of root or root‐induced changes in soil organic C (SOC), water‐soluble organic C (WSOC), and microbial biomass C (MBC) is important for understanding processes of soil C storage. A greenhouse study was conducted on a Bainsville loamy sand (Typic Hapludoll) to evaluate root or root‐induced quantitative and compositional changes in various SOC pools by growing corn ( Zea mays L.), a C 4 plant, on a historically C 3 soil. Significant shifts in 13 C of SOC pools, most noticeably in WSOC and MBC were observed. During the course of a growing season, the proportion of C 4 ‐derived C varied from 0 to 12.3% of whole SOC, from 0 to 30.7% of WSOC, and from 0 to 52% of MBC, indicating a major contribution of root or root‐induced C to various soil C components, especially WSOC and MBC. The amount of C 4 ‐derived C in the entire soil estimated by the 13 C natural abundance (δ 13 C) was remarkably consistent with the amount of C 4 ‐C retained in the soil microbial biomass, WSOC, and corn roots, suggesting that measurements of 13 C of the entire soil following the shift of C 3 to C 4 plants can be used as an indirect measure of root or root‐induced C pools during the growing period.