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Profile Analysis and Modeling of Reduced Tillage Effects on Soil Nitrous Oxide Flux
Author(s) -
Venterea Rodney T.,
Stanenas Adam J.
Publication year - 2008
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/jeq2007.0283
Subject(s) - nitrous oxide , tillage , denitrification , nitrification , soil water , chemistry , nitrate , soil science , environmental science , nitrite , nitrogen , flux (metallurgy) , conventional tillage , fertilizer , environmental chemistry , agronomy , organic chemistry , biology
The impact of no‐till (NT) and other reduced tillage (RT) practices on soil to atmosphere fluxes of nitrous oxide (N 2 O) are difficult to predict, and there is limited information regarding strategies for minimizing fluxes from RT systems. We measured vertical distributions of key microbial, chemical, and physical properties in soils from a long‐term tillage experiment and used these data as inputs to a process‐based model that accounts for N 2 O production, consumption, and gaseous diffusion. The results demonstrate how differences among tillage systems in the stratification of microbial enzyme activity, chemical reactivity, and other properties can control N 2 O fluxes. Under nitrification‐dominated conditions, simulated N 2 O emissions in the presence of nitrite (NO 2 −) were 2 to 10 times higher in NT soil compared to soil under conventional tillage (CT). Under denitrification‐dominated conditions in the presence of nitrate (NO 3 −), higher bulk density and water content under NT promoted higher denitrification rates than CT. These effects were partially offset by higher soluble organic carbon and/or temperature and lower N 2 O reduction rates under CT. The NT/CT ratio of N 2 O fluxes increased asNO 2 −orNO 3 −was placed closer to the surface. The highest NT/CT ratios of N 2 O flux (>30:1) were predicted for near‐surfaceNO 3 −placement, while NT/CT ratios < 1 were predicted forNO 3 −placement below 15 cm. These results suggest that N 2 O fluxes from RT systems can be minimized by subsurface fertilizer placement and by using a chemical form of fertilizer that does not promote substantialNO 2 −accumulation.