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Nitrogen dynamics in grain crop and legume pasture systems under elevated atmospheric carbon dioxide concentration: A meta‐analysis
Author(s) -
Lam Shu K.,
Chen Deli,
Norton Rob,
Armstrong Roger,
Mosier Arvin R.
Publication year - 2012
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.1365-2486.2012.02758.x
Subject(s) - agronomy , nitrogenase , legume , nitrous oxide , pasture , nitrogen fixation , nitrogen , carbon dioxide , carbon dioxide in earth's atmosphere , agroecosystem , fertilizer , crop , environmental science , chemistry , biology , agriculture , ecology , organic chemistry
Abstract Understanding nitrogen (N) removal and replenishment is crucial to crop sustainability under rising atmospheric carbon dioxide concentration ([ CO 2 ]). While a significant portion of N is removed in grains, the soil N taken from agroecosystems can be replenished by fertilizer application and N 2 fixation by legumes. The effects of elevated [ CO 2 ] on N dynamics in grain crop and legume pasture systems were evaluated using meta‐analytic techniques (366 observations from 127 studies). The information analysed for non‐legume crops included grain N removal, residue C : N ratio, fertilizer N recovery and nitrous oxide (N 2 O) emission. In addition to these parameters, nodule number and mass, nitrogenase activity, the percentage and amount of N fixed from the atmosphere were also assessed in legumes. Elevated [ CO 2 ] increased grain N removal of C 3 non‐legumes (11%), legumes (36%) and C 4 crops (14%). The C : N ratio of residues from C 3 non‐legumes and legumes increased under elevated [ CO 2 ] by 16% and 8%, respectively, but the increase for C 4 crops (9%) was not statistically significant. Under elevated [ CO 2 ], there was a 38% increase in the amount of N fixed from the atmosphere by legumes, which was accompanied by greater whole plant nodule number (33%), nodule mass (39%), nitrogenase activity (37%) and %N derived from the atmosphere (10%; non‐significant). Elevated [ CO 2 ] increased the plant uptake of fertilizer N by 17%, and N 2 O emission by 27%. These results suggest that N demand and removal in grain cropping systems will increase under future CO 2 ‐enriched environments, and that current N management practices (fertilizer application and legume incorporation) will need to be revised.