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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #345825
Research Project: Improving the Sustainability of Irrigated Farming Systems in Semi-Arid Regions

Location: Water Management and Systems Research

Title: Deficit irrigation drives maize root distribution and soil microbial communities with implications for soil carbon dynamics

Author
item Flynn, Nora
item Comas, Louise
item Stewart, Catherine
item FONTE, STEVEN - Colorad0 State University

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2020
Publication Date: 11/23/2020
Citation: Flynn, N.E., Comas, L.H., Stewart, C.E., Fonte, S.J. 2020. Deficit irrigation drives maize root distribution and soil microbial communities with implications for soil carbon dynamics. Soil Science Society of America Journal. 85(2):412-422. https://doi.org/10.1002/saj2.20201.
DOI: https://doi.org/10.1002/saj2.20201

Interpretive Summary: Water limits crop production in the Great Plains and around the world. While deficit irrigation (the application of less than full irrigation) is a promising management strategy for conserving water resources, little is known about how deficit irrigation impacts crop roots and critical soil characteristics, which can have long-term effects on soil function and, in turn, impact crop production. We assessed the impacts of deficit irrigation on corn root growth, soil carbon storage and soil microbial communities at two depths in the soil profile: 0-20 cm and 40-60 cm. Root growth increased under deficit irrigation deeper in the soil profile and resulted in a tendency for increased soil organic carbon stores deep in the soil profile. Analysis of the soil microbial community showed that stress from deficit irrigation decrease overall microbial growth and shifted community composition. Our results suggest impacts on crop roots, carbon dynamics and soil biological activity that should be considered alongside potential water savings while setting deficit irrigation management goals. Key Words: Deficit irrigation, water management, corn, root growth, soil microorganisms, soil carbon storage.

Technical Abstract: Improving water use efficiency and soil function is necessary to fulfil growing food demands under increased water scarcity. This study assessed impacts of water availability on maize root growth, Soil Organic Carbon (SOC) stocks and microbial community at two soil depths. Methods Root growth, soil carbon and nitrogen, and microbial community abundance and structure were analyzed from three treatments that differed in the amount of water availability during two growth periods (100, 65, 40% during late-vegetative and grain-filling) and one that shifted between the two periods (40% during the late vegetative and 80% during grain-filling). Results Root growth was similar among treatments in shallow soil but increased deeper in the soil profile with decreased water availability. SOC was higher with greater water availability at the 0-20 cm depth. At the 40-60 cm depth, SOC was higher with less water availability. In general, soil microorganisms were more abundant in treatments with greater moisture availability. Conclusions Deficit irrigation increases maize root growth and has potential to alter SOC sequestration dynamics in the soil surface and at depth. Microbial community analysis suggests that water availability early on had persistent impacts on soil microbial abundance and structure throughout the growing season. Impacts on roots, carbon dynamics and soil biological activity should be considered when setting water management goals.