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Dynamics of Atmospheric Nitrogen Deposition in a Temperate Calcareous Forest Soil
Author(s) -
Morier Isabelle,
Guenat Claire,
Siegwolf Rolf,
Védy JeanClaude,
Schleppi Patrick
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/jeq2007.0563
Subject(s) - calcareous , temperate forest , environmental chemistry , leaching (pedology) , chemistry , nitrogen , deposition (geology) , nitrate , soil horizon , ammonium , tracer , nitrification , plant litter , soil organic matter , litter , temperate climate , environmental science , agronomy , soil water , soil science , ecology , botany , nutrient , geology , biology , paleontology , organic chemistry , sediment , physics , nuclear physics
In temperate forest ecosystems, soil acts as a major sink for atmospheric N deposition. A 15 N labeling experiment in a hardwood forest on calcareous fluvisol was performed to study the processes involved. Low amounts of ammonium ( 15 NH 4 + ) or nitrate ( 15 NO 3 − ) were added to small plots. Soil samples were taken after periods ranging from 1 h to 1 yr. After 1 d, the litter layer retained approximately 28% of the 15 NH 4 + tracer and 19% of 15 NO 3 − The major fraction of deposited N went through the litter layer to reach the soil within the first hours following the tracer application. During the first day, a decrease in extractable 15 N in the soil was observed ( 15 NH 4 + : 50 to 5%; 15 NO 3 − : 60 to 12%). During the same time, the amount of microbial 15 N remained almost constant and the 15 N immobilized in the soil (i.e., total 15 N recovered in the bulk soil minus extractable 15 N minus microbial 15 N) also decreased. Such results can therefore be understood as a net loss of 15 N from the soil. Such N loss is probably explained by NO 3 − leaching, which is enhanced by the well‐developed soil structure. We presume that the N immobilization mainly occurs as an incorporation of deposited N into the soil organic matter. One year after the 15 N addition, recovery rates were similar and approximately three‐quarters of the deposited N was recovered in the soil. We conclude that the processes relevant for the fate of atmospherically deposited N take place rapidly and that N recycling within the microbes–plants–soil organic matter (SOM) system prevents further losses in the long term.