Soil CO2 and N2O fluxes from simple and diversified crop rotations in the Central Corn Belt

Authors: Chatterjee, Amitava; Emmett, Bryan; O'Brien, Peter; MCDANIEL, MARSHALL - Iowa State University; SAUER, THOMAS - Retired ARS Employee; LIEBMANN, MATT - Iowa State University

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2025
Publication Date: 7/10/2025
Citation: Chatterjee, A., Emmett, B.D., O'Brien, P.L., McDaniel, M., Sauer, T.J., Liebmann, M. 2025. Soil CO2 and N2O fluxes from simple and diversified crop rotations in the Central Corn Belt. Agrosystems, Geosciences & Environment. https://doi.org/10.1002/agg2.70171.
DOI: https://doi.org/10.1002/agg2.70171

Interpretive Summary: In the Corn Belt of the Midwest, crop rotation or the sequential planting of crops over time is limited to corn and soybean. This study compared the rates of gas emissions from soil, or fluxes, for 3-year, corn-soybean-oat/clover and 4-year, corn-soybean-oat/alfalfa-alfalfa rotations with the common 2-year corn-soybean rotation. Results showed that soil carbon dioxide gas flux of the 3-year and 4-year rotations was 36% and 54% greater than the 2-year rotation but nitrous oxide gas, which contributes to atmospheric warming, did not show a significant variation with rotation. The crop phases within a rotation had significant effects on soil carbon dioxide (alfalfa>oat=corn=soybean) and nitrous oxide gas (corn=alfalfa>soybean=oat) fluxes. These findings will be useful to recommend crop rotations based on gas fluxes. Findings could be of interest to scientists who will be interested to develop alternative rotation options to reduce gas fluxes.

Technical Abstract: United States agriculture has become productive but environmental consequences remain. For example, agriculture makes up a disproportionate share of net US greenhouse gas (GHG) emissions compared to its contribution to the economy. This and other environmental issues may be partially related to the specialization, or decrease in crop diversity, and reliance on synthetic fertilizer. In the US Corn Belt, crop rotational diversity is mostly limited to a richness of two (maize [Zea mays] and soybean [Glycine max]). We compared soil carbon dioxide (CO2) and nitrous oxide (N2O) fluxes from a long-term (9-11 year) experiment comparing the business-as-usual 2-year, maize-soybean rotation to two other diversified rotations; a 3-year maize-soybean-oat [Avena sativa]/red clover [Trifolium pratense]); and a 4-year (maize-soybean-oat/alfalfa [Medicago sativa]-alfalfa). Both 3-year and 4-year rotations also received composted cattle (Bos taurus) manure. We tested whether these diversified rotations that replace synthetic fertilizer with organic sources could decrease net soil GHG, because they have been shown to reduce nutrient leaching, and nutrient inputs are paired with C which may limit N2O flux. Considering all three years, soil CO2 flux in the 3-year or 4-year rotation were 36% and 54% greater than 2-year, driven by the maize phase, which might be due to prior years’ leguminous crops (red cover or alfalfa), tillage and manure. However, there were no rotational differences in soil N2O fluxes. The crop phases within a rotation had significant effects on soil CO2 (alfalfa> oat = maize = soybean) and N2O (maize=alfalfa>soybean=oat) fluxes. Soil temperature-crop phase interactions had more control over soil CO2 fluxes than did moisture. Inclusion of perennial crop, small grain-legume intercropping. Replacing inorganic with organic N sources is critical to consider for increasing rotation length and crop diversity of maize based crop rotation in the central Corn Belt of USA.