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Less efficient residue‐derived soil organic carbon formation under no‐till irrigated corn
Author(s) -
Leichty Sarah,
Cotrufo M. Francesca,
Stewart Catherine E.
Publication year - 2020
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.1002/saj2.20136
Subject(s) - residue (chemistry) , crop residue , agronomy , soil carbon , chemistry , soil water , topsoil , tillage , organic matter , soil organic matter , environmental chemistry , environmental science , soil science , ecology , agriculture , biology , biochemistry , organic chemistry
Soil organic carbon (SOC) stores a large portion of terrestrial C, yet the mechanisms that affect its formation efficiency under different residue management in irrigated systems are still not well understood. No‐till (NT) increases SOC concentrations in topsoil compared with conventional tillage (CT) but there is uncertainty surrounding the stability of these gains in irrigated systems. We investigated the effect of NT and CT residue management on CO 2 loss and SOC formation by applying isotopically ( 13 C) labeled residues on the surface or incorporated in the mineral soil of disturbed (i.e., CT) or undisturbed (i.e., NT) soil in a semiarid, NT, sprinkler‐irrigated, continuous corn ( Zea mays L.) field. We measured residue‐derived C in CO 2 , bulk soil, dissolved organic C, particulate organic matter (POM), and silt‐ and clay‐sized mineral‐associated organic matter (MAOM) fractions. Twelve months after residue addition, soils with surface‐applied residue produced 19% more CO 2 and formed 41% less SOC than residue‐incorporated soils. Across all treatments, 62% of residue‐derived C was recovered in POM, and 38% in the MAOM fractions. Residue‐derived bulk soil C formation was more efficient when the residue was incorporated (0.60) rather than surface‐applied (0.42), suggesting that mixing and burial of residue within the soil matrix is a key pathway of SOC formation. During the growing season, surface residue under NT management in irrigated systems is particularly vulnerable to decomposition and will require additional conservation strategies to generate long‐term C sequestration.