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Title: Hotspots of soil N2O emission enhanced through water absorption by plant residue

Authors:
; ; ; ; ; ; ; ORCiD logo
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
DOE - OTHERNSF
OSTI Identifier:
1399120
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Geoscience; Journal Volume: 10; Journal Issue: 7
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Kravchenko, A. N., Toosi, E. R., Guber, A. K., Ostrom, N. E., Yu, J., Azeem, K., Rivers, M. L., and Robertson, G. P.. Hotspots of soil N2O emission enhanced through water absorption by plant residue. United States: N. p., 2017. Web. doi:10.1038/ngeo2963.
Kravchenko, A. N., Toosi, E. R., Guber, A. K., Ostrom, N. E., Yu, J., Azeem, K., Rivers, M. L., & Robertson, G. P.. Hotspots of soil N2O emission enhanced through water absorption by plant residue. United States. doi:10.1038/ngeo2963.
Kravchenko, A. N., Toosi, E. R., Guber, A. K., Ostrom, N. E., Yu, J., Azeem, K., Rivers, M. L., and Robertson, G. P.. Mon . "Hotspots of soil N2O emission enhanced through water absorption by plant residue". United States. doi:10.1038/ngeo2963.
@article{osti_1399120,
title = {Hotspots of soil N2O emission enhanced through water absorption by plant residue},
author = {Kravchenko, A. N. and Toosi, E. R. and Guber, A. K. and Ostrom, N. E. and Yu, J. and Azeem, K. and Rivers, M. L. and Robertson, G. P.},
abstractNote = {},
doi = {10.1038/ngeo2963},
journal = {Nature Geoscience},
number = 7,
volume = 10,
place = {United States},
year = {Mon Jun 05 00:00:00 EDT 2017},
month = {Mon Jun 05 00:00:00 EDT 2017}
}
  • N2O is a highly potent greenhouse gas and arable soils represent its major anthropogenic source. Field-scale assessments and predictions of soil N2O emission remain uncertain and imprecise due to the episodic and microscale nature of microbial N2O production, most of which occurs within very small discrete soil volumes. Such hotspots of N2O production are often associated with decomposing plant residue. Here we quantify physical and hydrological soil characteristics that lead to strikingly accelerated N2O emissions in plant residue-induced hotspots. Results reveal a mechanism for microscale N2O emissions: water absorption by plant residue that creates unique micro-environmental conditions, markedly different frommore » those of the bulk soil. Moisture levels within plant residue exceeded those of bulk soil by 4–10-fold and led to accelerated N2O production via microbial denitrification. The presence of large (Ø >35 μm) pores was a prerequisite for maximized hotspot N2O production and for subsequent diffusion to the atmosphere. Understanding and modelling hotspot microscale physical and hydrologic characteristics is a promising route to predict N2O emissions and thus to develop effective mitigation strategies and estimate global fluxes in a changing environment.« less
  • N 2O is a highly potent greenhouse gas and arable soils represent its major anthropogenic source. Field-scale assessments and predictions of soil N 2O emission remain uncertain and imprecise due to the episodic and microscale nature of microbial N 2O production, most of which occurs within very small discrete soil volumes. Such hotspots of N 2O production are often associated with decomposing plant residue. Here we quantify physical and hydrological soil characteristics that lead to strikingly accelerated N 2O emissions in plant residue-induced hotspots. Results reveal a mechanism for microscale N 2O emissions: water absorption by plant residue that createsmore » unique micro-environmental conditions, markedly different from those of the bulk soil. Moisture levels within plant residue exceeded those of bulk soil by 4–10-fold and led to accelerated N 2O production via microbial denitrification. The presence of large (Ø >35 μm) pores was a prerequisite for maximized hotspot N 2O production and for subsequent diffusion to the atmosphere. Understanding and modelling hotspot microscale physical and hydrologic characteristics is a promising route to predict N 2O emissions and thus to develop effective mitigation strategies and estimate global fluxes in a changing environment.« less
  • In addition to buffering plants from water stress during severe droughts, plant water storage (PWS) alters many features of the spatio-temporal dynamics of water movement in the soil–plant system. How PWS impacts water dynamics and drought resilience is explored using a multi-layer porous media model. Here, the model numerically resolves soil–plant hydrodynamics by coupling them to leaf-level gas exchange and soil–root interfacial layers. Novel features of the model are the considerations of a coordinated relationship between stomatal aperture variation and whole-system hydraulics and of the effects of PWS and nocturnal transpiration (F e,night) on hydraulic redistribution (HR) in the soil.
  • Root carbon (C) inputs may regulate decomposition rates in soil, and in this study we ask: how do labile C inputs regulate decomposition of plant residues, and soil microbial communities? In a 14 d laboratory incubation, we added C compounds often found in root exudates in seven different concentrations (0, 0.7, 1.4, 3.6, 7.2, 14.4 and 21.7 mg C g{sup -1} soil) to soils amended with and without {sup 13}C-labeled plant residue. We measured CO{sub 2} respiration and shifts in relative fungal and bacterial rRNA gene copy numbers using quantitative polymerase chain reaction (qPCR). Increased labile C input enhanced totalmore » C respiration, but only addition of C at low concentrations (0.7 mg C g{sup -1}) stimulated plant residue decomposition (+2%). Intermediate concentrations (1.4, 3.6 mg C g{sup -1}) had no impact on plant residue decomposition, while greater concentrations of C (> 7.2 mg C g{sup -1}) reduced decomposition (-50%). Concurrently, high exudate concentrations (> 3.6 mg C g{sup -1}) increased fungal and bacterial gene copy numbers, whereas low exudate concentrations (< 3.6 mg C g{sup -1}) increased metabolic activity rather than gene copy numbers. These results underscore that labile soil C inputs can regulate decomposition of more recalcitrant soil C by controlling the activity and relative abundance of fungi and bacteria.« less