EGU21-2986
https://doi.org/10.5194/egusphere-egu21-2986
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Tillage-residue management affects the distribution, storage and turnover of mineral-associated organic matter – A case study from northern Mexico 

Carlos Romero1,2, Xiying Hao2, Paul Hazendonk3, Timothy Schwinghamer2, Martin Chantigny4, Simon Fonteyne5, and Nele Verhulst5
Carlos Romero et al.
  • 1Department of Biological Sciences, Faculty of Arts & Science, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada (carlos.romero@uleth.ca).
  • 2Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1st Ave S, Lethbridge, AB, T1J 4B1, Canada.
  • 3Department of Chemistry and Biochemistry, Faculty of Arts & Science, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3M4, Canada.
  • 4Québec Research and Development Centre, Agriculture and Agri-Food Canada, 2560 Boulevard Hochelaga, Québec, QC, G1V 2J3, Canada.
  • 5International Maize and Wheat Improvement Center (CIMMYT), Carretera México-Veracruz km 45, Texcoco, Edo. de México, 56237, México.

Managing croplands for increased storage of soil organic matter (SOM) is a critical step towards developing resilient farming systems in a changing climate. We examined SOM dynamics in a wheat (Triticum durum L.) – maize (Zea mays L.) irrigated bed planting system established near Ciudad Obregón, Sonora, Mexico. Soil samples (0 – 15 cm) were collected from conventionally tilled raised beds (CTB) with all crop residues incorporated (CTB-I) and permanent raised beds (PB) with crop residues burned (PB-B), removed (PB-R), partly retained (PB-P) or fully retained (PB-K) receiving 0, 150 or 300 kg N ha-1, and analyzed for organic C (OC), total N (TN) and δ13C in whole-soil, light fraction (LF) and coarse- (sand) and fine- (silt and clay) mineral-associated organic matter (MAOM). Results indicated that PB-K and PB-B increased soil OC (P < 0.05) in whole-soil relative to CTB-I, mainly through increases in sand- and silt-size MAOM, respectively. Similarly, N-fertilization increased soil OC and TN contents in whole-soil, coarse-MAOM, and fine-MAOM, but not in the LF pool. Soil δ13C was higher (P < 0.05) in PB-K (-20.18‰) relative to PB-B (-20.67‰), possibly due to the stabilization of partly decomposed maize-C in silt- and clay-size MAOM. The composition of SOM surveyed by CPMAS 13C NMR was not affected by tillage-residue management and roughly consisted of 35% O-alkyl-C, 31% alkyl-C, 24% aromatic-C, and 10% carboxyl-C. Our results indicate that long-term PB-K and PB-B adoption increased surface soil OC contents relative to CTB-I, even though pathways of SOM stabilization differed between systems. Under PB-K, accumulation of fine-MAOM was mostly related to straw-C inputs, whereas in PB-B it was closely associated with black-C precursors. Fine-MAOM appeared responsive to crop residue management and should be therefore considered when analyzing mechanisms of SOM stabilization in irrigated croplands.

How to cite: Romero, C., Hao, X., Hazendonk, P., Schwinghamer, T., Chantigny, M., Fonteyne, S., and Verhulst, N.: Tillage-residue management affects the distribution, storage and turnover of mineral-associated organic matter – A case study from northern Mexico , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2986, https://doi.org/10.5194/egusphere-egu21-2986, 2021.

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