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Dissimilatory nitrate reduction to ammonium and N2O flux: effect of soil redox potential and N fertilization in loblolly pine forests

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Title Dissimilatory nitrate reduction to ammonium and N2O flux: effect of soil redox potential and N fertilization in loblolly pine forests
Not Available
 
Creator K. J. Minick
C. B. Pandey
T. R. Fox
Santosh Subedi
 
Subject Pinustaeda . Mineralization . Nitrification . Anaerobic . Denitrification . Nitrate
 
Description Not Available
Nitrogen (N) fertilization and soil redox potential
influence N cycling processes in forested ecosystems. Gross N
transformations are indicators of NH4+ and NO3 − production
and consumption within soil. Furthermore, dissimilatory nitrate reduction to ammonium (DNRA), a typically overlooked
process in terrestrial N cycling, can conserve N within soil by
reducing losses of soil N via NO3 − leaching and denitrification. We tested the effects of urea fertilization and soil redox
on microbial N cycling processes and N2O fluxes using a 15N
tracer experiment in soils from loblolly pine plantations located in different physiographical regions (i.e., Coastal Plain of
North Carolina and Piedmont of Virginia). Mineral soils (0–
15 cm) from fertilized and unfertilized plots were incubated at
high (Eh, 200 to 400 mV) and low redox potential (Eh, −100
to 100 mV). Site differences were limited primarily to edaphic
factors, although gross N mineralization was higher in NC.
Gross nitrification, DNRA, and NO3– −–N concentrations
were higher in soils from fertilized plots. DNRA was higher
at high compared to low redox potential, while N2O fluxes
were higher at low redox potential. Fluxes of N2O were further enhanced in fertilized treatments incubated at low redox
potential. DNRA was positively correlated with NO3 − availability, but not to soil C pools. Furthermore, DNRA was negatively correlated with C/NO3 − ratio, implying that NO3 − pool
size was the primary factor influencing DNRA. These results
suggest N fertilization has alleviated limitations to nitrification, DNRA, and N2O production processes and that gaseous
losses of N will prevail over N conservation pathways at low
soil redox potentials.
Not Available
 
Date 2019-07-24T10:22:04Z
2019-07-24T10:22:04Z
2016-03-01
 
Type Research Paper
 
Identifier Not Available
http://krishi.icar.gov.in/jspui/handle/123456789/21697
 
Language English
 
Publisher Springer