Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2004
Publication Date: 11/1/2004
Citation: Adviento-Borbe, A., Doran, J.W., Dobermann, A. 2004. Soil electrical conductivity and moisture effects on greenhouse gas emissions. Agronomy Abstracts #3357. Interpretive Summary:
Technical Abstract: This study was conducted to determine the effects of soil electrical conductivity (EC) and soil moisture on microbial nitrification, denitrification and respiration and associated N2O and CO2 emissions in four soils. Surface soil A horizons from intensively managed field sites were washed, repacked to 1.2 Mg m-3 and brought to 60% (aerobic) and 90% (anaerobic) water filled pore spaces (WFPS). Salt mixtures of KCl, CaCl2 and Na2SO4 were added to each of the moist soil cores at rates that resulted in EC of approximately 0.5, 1.0, 1.5 and 2.0 dS m-1. The soil cores were incubated at 25oC for 10 d during which daily gas samples of headspace were analyzed for N2O and CO2. At EC >1.0, enitrification increased and nitrification decreased, as indicated by changes in soil NH4, NO3 and N2O emission rates. In the presence of large ion concentrations in the soil solution, nitrifier activity was limited. Total N2O production was small at 2.0 dS m-1 and 60 % WFPS. In contrast, when soil moisture content was high (90 % WFPS), 10 times more N2O was produced regardless of EC values, although N2O production tended to increase when EC exceeded 1 dS m-1. It is likely that denitrification was the major source of N2O production in these cultivated soils. Microbial respiration was high at 0.5 dS m-1 EC, both for 60 and 90 % WFPS.