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Seasonal Variations in Denitrification and Nitrous Oxide Evolution at the Landscape Scale
Author(s) -
Kessel C.,
Pennock D. J.,
Farrell R. E.
Publication year - 1993
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1993.03615995005700040018x
Subject(s) - denitrification , nitrous oxide , environmental science , growing season , hydrology (agriculture) , fertilizer , tillage , agronomy , ecology , environmental chemistry , soil science , chemistry , nitrogen , biology , geology , geotechnical engineering , organic chemistry
This study was conducted to examine the seasonal and spatial variability of denitrification in various landform elements in a pea ( Pisum sativum L.) field at Blaine Lake, Saskatchewan, Canada. The distributions of denitrification activity and N 2 O evolution were highly skewed, and could not be log‐transformed to yield normal distributions. Consequently, ordinary statistical procedures (i.e., those based on a normal distribution) were considered inappropriate for this study, and nonparametric statistics were used to describe the data. Denitrification activity and N 2 O evolution exhibited similar temporal and landscape‐scale patterns and were highly correlated, suggesting that denitrification was the main source of N 2 O evolution. In general, N 2 O evolution accounted for ≅41% of the denitrification activity. Maximum rates of denitrification were low prior to spring tillage and seeding, increased during the first half of the growing season (following the addition of fertilizer N), and decreased toward the end of the growing season; denitrification had essentially ceased by the fall sampling. Statistical outliers for denitrification activity, i.e., hotspots of activity, occurred predominantly at low levels of denitrification activity and were completely absent when denitrification activity was at its maximum. Therefore, the importance of hotspots of activity for estimating seasonal rates of denitrification appears to be limited. Soil water content was the most dominant factor controlling denitrification activity, followed by the concentration of NH + 4 , total soil respiration, and NO − 3 . The intensity of denitrification was controlled largely by hydrologic processes, which, in turn, were influenced by the topography of the landscape. Nevertheless, the landscape‐scale patterns of denitrification and N 2 O evolution were intensity‐independent and remained consistent throughout the season.