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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #334319

Title: Cropping system effects on soil organic C storage in surface and subsoils

item POFFENBARGER, HANNA - Iowa State University
item Cambardella, Cynthia
item LIEBMAN, MATTHEW - Iowa State University
item MALLARINO, ANTONIO - Iowa State University
item Olk, Daniel - Dan
item SIX, JOHAN - Eldgenossische Technische Hochschule (ETH)
item CASTELLANO, MICHAEL - Iowa State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/6/2016
Publication Date: 11/6/2016
Citation: Poffenbarger, H., Cambardella, C.A., Liebman, M., Mallarino, A., Olk, D.C., Six, J., Castellano, M. 2016. Cropping system effects on soil organic C storage in surface and subsoils. In: Procedings of ASA/CSSA/SSSA Annual Meeting, November 6-9, 2016, Phoenix, AZ.

Interpretive Summary:

Technical Abstract: A large proportion of soil organic C (SOC) is in subsoil, yet few studies have evaluated cropping system effects on SOC below the plow layer. We hypothesized that cropping systems with greater belowground C inputs would increase SOC stocks by delivering C to the relatively C-depleted subsoil. Using three long-term field trials in Iowa (study durations of 60, 35, and 12 years), we examined the effects of cropping system (corn-soybean-oat/alfalfa-alfalfa or corn-corn-oat/alfalfa-alfalfa vs. corn-soybean rotation) on SOC and N content at different depths throughout the soil profile. Average annual C inputs were similar for both cropping systems, but the proportion of C delivered belowground was approximately twice as great in the extended rotations. Although belowground C inputs were greater in the extended rotations, differences in SOC stocks due to cropping system were within ~10% of the mean. Soil organic C accumulation was observed at depth (15-100 cm) but not at the surface (0-15 cm) across all sites and rotations. Our research highlights the importance of the subsoil as a C sink in agricultural systems.