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Soil Electrical Conductivity and Water Content Affect Nitrous Oxide and Carbon Dioxide Emissions in Intensively Managed Soils
Author(s) -
AdvientoBorbe M. A. A.,
Doran J. W.,
Drijber R. A.,
Dobermann A.
Publication year - 2006
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2006.0109
Subject(s) - soil water , nitrous oxide , carbon dioxide , water content , chemistry , denitrification , nitrification , nitrogen , fertilizer , environmental chemistry , agronomy , zoology , environmental science , soil science , geotechnical engineering , organic chemistry , engineering , biology
Accumulation of soluble salts resulting from fertilizer N may affect microbial production of N 2 O and CO 2 in soils. This study was conducted to determine the effects of electrical conductivity (EC) and water content on N 2 O and CO 2 production in five soils under intensive cropping. Surface soils from maize fields were washed, repacked and brought to 60% or 90% water‐filled pore space (WFPS). Salt mixtures were added to achieve an initial in situ soil EC of 0.5, 1.0, 1.5 and 2.0 dS m −1 The soil cores were incubated at 25°C for 10 d. Average CO 2 production decreased with increasing EC at both soil water contents, indicating a general reduction in microbial respiration with increasing EC. Average cumulative N 2 O production at 60% WFPS decreased from 2.0 mg N 2 O‐N m −2 at an initial EC of 0.5 dS m −1 to 0.86 mg N 2 O‐N m −2 at 2.0 dS m −1 At 90% WFPS, N 2 O production was 2 to 40 times greater than that at 60% WFPS and maximum N 2 O losses occurred at the highest EC level of 2.0 dS m −1 Differences in the magnitude of gas emissions at varying WFPS were due to available substrate N and the predominance of nitrification under aerobic conditions (60% WFPS) and denitrification when oxygen was limited (90% WFPS). Differences in gas emissions at varying soil EC may be due to changes in mechanisms of adjustment to salt stress and ion toxicities by microbial communities. Direct effects of EC on microbial respiration and N 2 O emissions need to be accounted for in ecosystems models for predicting soil greenhouse gas emissions.