A deeper look at the relationship between root carbon pools and the vertical
distribution of the soil carbon pool
Ranae Dietzel, Matt Liebman, and Sotirios Archontoulis
Department of Agronomy, Iowa State University, Ames, 50011, United States
Received: 25 Jan 2017 – Accepted for review: 23 Feb 2017 – Discussion started: 27 Feb 2017
Abstract. Plant root material makes a substantial contribution to the soil organic carbon (C) pool, but this contribution is disproportionate below 20 cm, where 30 % of root mass and 50 % of soil organic C is found. Root carbon inputs changed drastically when native perennial plant systems were shifted to cultivated annual plant systems. We used the reconstruction of a native prairie and a continuous maize field to examine both the relationship between root carbon and soil carbon and the fundamental rooting system differences between the vegetation under which the soils developed versus the vegetation under which the soils continue to change. In all treatments we found that root C : N ratios increased with depth, which may help explain why an unexpectedly large proportion of soil organic C is found below 20 cm. Measured root C : N ratios and turnover times along with modeled root turnover dynamics showed that in moving from prairie to maize, a large, structural-tissue dominated root C pool with slow turnover, concentrated at shallow depths was replaced by a small, non-structural-tissue dominated root C pool with fast turnover evenly distributed in the soil profile. These differences in rooting systems suggest that while prairie roots contribute more C to the soil than maize at shallow depths, maize may contribute more C to the soil than prairies at deeper depths.
Dietzel, R., Liebman, M., and Archontoulis, S.: A deeper look at the relationship between root carbon pools and the vertical
distribution of the soil carbon pool, SOIL Discuss., doi:10.5194/soil-2017-5, in review, 2017.
Ranae Dietzel et al.
Ranae Dietzel et al.
A deeper look at the relationship between root carbon pools and the vertical distribution of the soil carbon pool: Data and Code