33 Biogeochemical Cycling and Microbial Dynamics in Response to Pulse Events

Friday, 13 April 2018
1:30 PM - 5:30 PM
Room 301 A

CONSERVATION AGRICULTURAL MANAGEMENT PRACTICES OFFSET THE LOSS OF 13C-LABELED GLUCOSE IN SOIL UNDER MOISTURE PULSE EVENTS

Paper number: 33-5
Program: Theme Sessions
Time: 2:35 PM – 2:55 PM

Authors

  • Lidong LI Presenting Author
    University of Tennessee Institute of Agriculture, KNOXVILLE, TN
  • Sean M. Schaeffer
    University of Tennessee, Knoxville, TN

Abstract

Understanding the mechanisms of carbon (C) sequestration in soil under drying-rewetting cycles is essential for predicting the terrestrial C pool facing climate change. A 24-day incubation in microcosms was conducted with an agricultural soil under 36 years of conservation management. We added 13C-labelled glucose and applied different frequencies of drying-rewetting cycles to the microcosms. The fate of the 13C-labelled substrate in active and passive C pools was traced. Structural equation modelling was conducted to determine the relative importance of physical, chemical, and biochemical controls of the labile C accumulation in soil. The structural equation model shows that H2O2-resistant C pool is the major control of the newly added labile C accumulation under drying-rewetting cycles. It indicates that chemical stabilization and biochemical alteration rather than physical protection are major controls of labile C sequestration in soil under drying-rewetting cycles. The model also demonstrates that although the long-term agricultural conservation management practices can completely counteract the loss of soil total C caused by moisture pulse events, they are only able to offset the loss of newly added labile C to a limited extent.

Geological Society of America Abstracts with Programs. Vol. 50, No. 3

doi: 10.1130/abs/2018SE-312048

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