The role of abiotic and coupled biotic/abiotic mineral controlled redox processes in nitrate reduction

C. J. Matocha, P. Dhakal, S. M. Pyzola

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

30 Scopus citations


Nitrogen is a major nutrient element which often limits productivity in natural and agroecosystems. Paradoxically, nitrogen is also readily lost through processes such as denitrification in soil environments. Historically, heterotrophic denitrification has been studied assuming soil organic carbon is the sole electron donor with little recognition for coupling with other elemental cycles. Recent discoveries have emerged which show a strong coupling between the iron and nitrogen cycles. Where soil iron(III) is utilized as a terminal electron acceptor during organic carbon respiration, the resulting iron(II) can serve as an electron donor during nitrate reduction. One example is the reduction of nitrate coupled to iron(II) oxidation by mixotrophic microorganisms in a process called nitrate-dependent, iron(II) oxidation. Nitrate-dependent, iron(II) oxidation is shown to occur in a moderately well-drained and a well-drained agricultural soil under anoxic conditions. The rates of nitrate reduction by heterotrophic bacteria are comparable to those by iron(II) oxidizers. Another example is the abiotic reduction of nitrate by iron(II) minerals which form in anoxic soil environments such as green rust. There is also the possibility of coupled biological-abiological processes where microbial Fe(III) reduction to Fe(II) is coupled to secondary chemical reactions involving nitrite and siderite, the latter represents an important Fe(II) mineral. These results underscore the complexity of the nitrogen cycle and will hopefully inspire future studies that will unravel the mechanisms behind soil Fe(II) oxidation by nitrate.

Original languageEnglish
Title of host publicationAdvances in Agronomy
Number of pages34
StatePublished - 2012

Publication series

NameAdvances in Agronomy
ISSN (Print)0065-2113

Bibliographical note

Funding Information:
This research was supported by National Research Initiative Competitive Grant no. 2007-35107-18311 from the USDA Cooperative State Research, Education, and Extension service. We thank Mark Coyne for insightful discussions, Dave McNear for generous use of the FTIR spectrophotometer, and Martin Vandiviere for assistance in the laboratory.


  • Carbon
  • Denitrification
  • Electron transfer
  • Iron
  • Kinetics
  • Lithotrophic
  • Nitrate reductase
  • Nitrite
  • Nitrogen
  • Nitrous oxide
  • Oxidation
  • Siderite

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science


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