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Nonlinear response of N 2 O flux to incremental fertilizer addition in a continuous maize ( Zea mays L.) cropping system
Author(s) -
McSwiney Claire P.,
Robertson G. Philip
Publication year - 2005
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.1365-2486.2005.01040.x
Subject(s) - fertilizer , agronomy , urea , human fertilization , nitrogen , growing season , zea mays , cropping system , zoology , crop , crop yield , flux (metallurgy) , mathematics , environmental science , chemistry , biology , organic chemistry
The relationship between nitrous oxide (N 2 O) flux and N availability in agricultural ecosystems is usually assumed to be linear, with the same proportion of nitrogen lost as N 2 O regardless of input level. We conducted a 3‐year, high‐resolution N fertilizer response study in southwest Michigan USA to test the hypothesis that N 2 O fluxes increase mainly in response to N additions that exceed crop N needs. We added urea ammonium nitrate or granular urea at nine levels (0–292 kg N ha −1 ) to four replicate plots of continuous maize. We measured N 2 O fluxes and available soil N biweekly following fertilization and grain yields at the end of the growing season. From 2001 to 2003 N 2 O fluxes were moderately low (ca. 20 g N 2 O‐N ha −1 day −1 ) at levels of N addition to 101 kg N ha −1 , where grain yields were maximized, after which fluxes more than doubled (to >50 g N 2 O‐N ha −1 day −1 ). This threshold N 2 O response to N fertilization suggests that agricultural N 2 O fluxes could be reduced with no or little yield penalty by reducing N fertilizer inputs to levels that just satisfy crop needs.