Predicted annual biomass input to maintain soil organic carbon under contrasting management

Authors: Gollany, Hero; Nash, Patrick; Johnson, Jane; Barbour, Nancy

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2019
Publication Date: 1/22/2020
Citation: Gollany, H.T., Nash, P.R., Johnson, J.M., Barbour, N.W. 2020. Predicted annual biomass input to maintain soil organic carbon under contrasting management. Agronomy Journal. 2020:1-14. https://doi.org/10.1002/agj2.20068.
DOI: https://doi.org/10.1002/agj2.20068

Interpretive Summary: Corn residue is an important source of lignocellulosic feedstocks for meeting the USA renewable energy goals. However, there is uncertainty in how much biomass can be sustainably harvested. The objectives of this study were to: 1) simulate soil organic carbon dynamics in the top 12 inches soil depths for the 2005-2015 study period using CQESTR, a process-based C model; 2) establish trends in soil organic carbon with residue removal and tillage management over the predictive period of 2016-2035; and 3) recommend practices to maintain soil organic carbon stocks in a corn-soybean rotation with corn residue removal in western Minnesota, USA. The residue removal treatments in the chisel tillage since 1995 (CT95) and no tillage since 1995 (NT95) fields were initiated in 2005, and in 2006 for the no tillage since 2005 (NT05) field. Corn residue removal treatments were none, cob removal, about 50% removal, and about 75% removal. Only the NT05 field, without residue removal and with addition of 2.81 ton/ac/year annual above-ground biomass, was predicted to increase soil organic carbon stocks by 0.14 ton/ac/year in the top 12 inches soil by 2035. It was concluded that only the NT05 field has the potential to maintain soil organic carbon at the current rate of biomass addition, and a minimal annual aboveground carbon input of 1.67 ton/acre/year is required to maintain soil organic carbon until 2035. These simulation results indicate that caution should be used in removing residue from these fields especially under conventional tillage. [GRACEnet/REAP Publication].

Technical Abstract: Corn (Zea mays L.) residue is an important source of lignocellulosic feedstocks for meeting the US renewable energy goals. However, there is uncertainty in how much biomass can be sustainably harvested. The objectives of this study were to: 1) simulate soil organic carbon (SOC) dynamics in the 0-20, 20-30, and 0-30 cm soil depths for the 2005-2015 study period using CQESTR, a process-based C model; 2) establish trends in SOC with residue removal and tillage management over the predictive period of 2016-2035; and 3) recommend practices to maintain SOC stocks in a corn-soybean (Glycine max L. [Merr.]) rotation with corn residue removal in western Minnesota, US. The residue removal treatments in the chisel tillage since 1995 (CT95) and no tillage since 1995 (NT95) fields were initiated in 2005, and in 2006 for the no tillage since 2005 (NT05) field. Corn residue removal treatments were none, cob removal, ~50% removal, and ~75% removal (R0, RCob, R50, and R75, respectively). Only R0 in NT05 increased (0.32 Mg C ha/yr) SOC stocks in the top 30 cm soil depth by 2035 with annual above-ground biomass input of 6.30 Mg ha/yr. It was concluded that only the NT05 field has the potential to maintain SOC at the current rate of biomass addition, and a minimal annual aboveground C (MSC) input of 3.75 Mg C ha/yr is required to maintain SOC until 2035. These simulation results indicate that caution should be used in removing residue from these fields especially under conventional tillage. [GRACEnet/REAP Publication].