207-11 Nitrogen Dynamics in Grain Crop and Legume Pasture Systems Under Elevated Carbon Dioxide: A Meta-Analysis.

See more from this Division: ASA Section: Climatology & Modeling
See more from this Session: Agroclimatology and Agronomic Modeling.I. Climate Change Impacts On Agricultural Systems
Tuesday, October 23, 2012: 3:45 PM
Duke Energy Convention Center, Room 235, Level 2
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Deli Chen1, Shu Kee Lam1, Robert Norton2, Roger Armstrong3 and Arvin Mosier1, (1)University of Melbourne, Victoria, Australia
(2)International Plant Nutrition Institute, Horsham, Victoria, Australia
(3)Department of Primary Industries, Victoria, Horsham, Victoria, Australia
Understanding nitrogen (N) removal and replenishment is crucial to crop sustainability under rising atmospheric carbon dioxide concentration ([CO2]). The effects of elevated [CO2] 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, nitrous oxide (N2O) emission and fertilizer N recovery. 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 [CO2] increased grain N removal (11–36%) of C3 non-legumes, legumes and C4 crops. The C:N ratio of residues from C3 non-legumes and legumes increased under elevated [CO2] by 16% and 8%, respectively, but the increase for C4 crops (9%) was not statistically significant. Elevated [CO2] increased the plant uptake of fertilizer N by 17%, and N2O emission by 27%. Under elevated [CO2], 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). These results suggest that N demand and removal in grain cropping systems will increase under future CO2-enriched environments, and that current N management practice needs to be revised.
See more from this Division: ASA Section: Climatology & Modeling
See more from this Session: Agroclimatology and Agronomic Modeling.I. Climate Change Impacts On Agricultural Systems