Tillage and residue management effects on soil carbon and nitrogen under irrigated continuous corn

Authors: Schmer, Marty; Varvel, Gary; Follett, Ronald; Jin, Virginia; Wienhold, Brian

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2014
Publication Date: 11/11/2014
Publication URL: http://handle.nal.usda.gov/10113/59784
Citation: Schmer, M.R., Varvel, G.E., Follett, R.F., Jin, V.L., Wienhold, B.J. 2014. Tillage and residue management effects on soil carbon and nitrogen under irrigated continuous corn. Soil Science Society of America Journal. 78:1987-1996. DOI: 10.2136/sssaj2014.04.0166.

Interpretive Summary: Corn stover is increasingly harvested and used as forage for beef cattle and will likely be the primary feedstock in the Corn Belt region for an emerging cellulosic biofuel industry. We monitored grain yield, soil organic carbon (SOC), and total soil N (0 to 150 cm) in a ten year, irrigated, continuous corn study under conventional disk tillage and no-till with variable corn stover removal rates (none, medium, high). We also determined SOC additions by corn into the soil profile using natural abundance C isotope compositions. Mean grain yields were lower when corn stover was harvested under conventional tillage while grain yields were higher for no-till when corn stover was harvested compared with no stover removal. Changes in SOC and total soil N occurred at near surface soil depths while cumulative (0 to 150 cm) changes were similar between 2001 and 2010. Turnover of SOC occurred throughout the soil profile suggesting further investigations in SOC cycling below near-surface soil layers is warranted.

Technical Abstract: Demand for corn (Zea mays L.) stover as forage or as a cellulosic biofuel has increased the importance of determining the effects of residue removal on biomass production and the soil resource. Objectives were to evaluate grain yield, soil organic carbon (SOC), and total soil N (0 to 150 cm) in a ten year, irrigated, continuous corn study under conventional disk tillage (CT) and no-till (NT) with variable corn stover removal rates (none, medium, high). Natural abundance C isotope compositions were used to determine C additions by corn (C4-C) to the soil profile and to evaluate the retention of residual C3-C. After ten years of management treatments, mean grain yields were 2.0% to 2.6% lower with CT when residue was removed while grain yield was 7.5% to 8.6% higher for NT when residue was removed compared with no residue removal. Turnover of SOC occurred as C3-C stocks were replaced by C4-C in the 0 to 120 cm soil profile. Total SOC- and N- stocks changed mainly in surface soils (0 to 30 cm) but not the whole profile (0 to 150 cm). Specifically, SOC declines occurred under CT (P=0.0364) at 0 to 15 cm and from residue management at 15 to 30 cm. Total soil N was greatest when no residue was removed (P=0.0073) compared to high residue removal at 0 to 15 cm. Long-term NT ameliorated residue removal effects by maintaining near-surface SOC levels. Results support the need to evaluate SOC cycling processes below near-surface soil layers.