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Ten years of elevated atmospheric carbon dioxide alters soil nitrogen transformations in a sheep‐grazed pasture
Author(s) -
RÜTTING TOBIAS,
CLOUGH TIM J.,
MÜLLER CHRISTOPH,
LIEFFERING MARK,
NEWTON PAUL C. D.
Publication year - 2010
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2009.02089.x
Subject(s) - mineralization (soil science) , pasture , environmental chemistry , carbon dioxide , nitrogen cycle , nitrogen , carbon dioxide in earth's atmosphere , grassland , environmental science , soil carbon , biogeochemical cycle , organic matter , soil water , chemistry , temperate climate , agronomy , soil science , ecology , biology , organic chemistry
The increasing concentration of atmospheric carbon dioxide (CO 2 ) is expected to lead to enhanced competition between plants and microorganisms for the available nitrogen (N) in soil. Here, we present novel results from a 15 N tracing study conducted with a sheep‐grazed pasture soil that had been under 10 years of CO 2 enrichment. Our study aimed to investigate changes in process‐specific gross N transformations in a soil previously exposed to an elevated atmospheric CO 2 (eCO 2 ) concentration and to examine indicators for the occurrence of progressive nitrogen limitation (PNL). Our results show that the mineralization–immobilization turnover (MIT) was enhanced under eCO 2 , which was driven by the mineralization of recalcitrant organic N. The retention of N in the grassland was enhanced by increased dissimilatory NO 3 − reduction to NH 4 + (DNRA) and decreased NH 4 + oxidation. Our results indicate that heterotrophic processes become more important under eCO 2 . We conclude that higher MIT of recalcitrant organic N and enhanced N retention are mechanisms that may alleviate PNL in grazed temperate grassland.