358-12 Emissions of Nitrous Oxide and Carbon Dioxide in Maize Under Production Systems of Different Intensification.
Poster Number 1221
CO2 emissions varied between 35.8 and 227.5 mg CO2 m-2 h-1, with significant differences between dates (p<0.05). The CO2 flows increased from mid-spring to early summer, in conjunction with plant biomass increase, and then decline into the fall. A CO2 peak (54 kg ha-1 day-1) was observed days at anthesis, in association with high soil temperatures (23.7oC) but with low moisture content, 30% water-filled pore space. Trough physiological maturity, the average CO2 flow was of 51.6 mg m-2 h-1; however, it increases to 113.2 mg CO2 m-2 h-1 in April, because of an increase in soil temperature.
In general, N2O emissions were low with maximum emissions ranging from 18.9 to 20.8 mg N2O m-2 h-1 in November and December, representing a loss of 4.5 and 4.9 g N2O ha-1 day- 1. 0.05) entre los muestreos de marzo y abril, y en general con">In the final stages of crop growth, N2O flow was low, between 2.9 and 3.0 ug N2O m-2 h-1, without significant differences between samplings in March and April, and in general those made in February (p> 0.05). These results could be due to the low moisture content which did not exceed 50% water-filled pore space. In most months, rainfalls were below the historical record, and the soil surface remained below field capacity even after a rainfall event. The N2O emission peaks were observed in late spring and early summer, when rainfalls were more intense and frequent, 151 mm in 11 rainfall events in November. At this time, high nitrate levels also favored increased emissions of N2O. Also, N2O peaks were recorded in February as rainfalls totaled 105 mm, and temperatures were high, between 23oC and 27oC. Since soil moisture content was mostly below or close to the field capacity, with water-filled pore space between 13% and 51%, it is likely that the main contribution to the production of N2O has been via nitrification.
0.05) emisiones acumuladas de CO2 y N2O durante 146 días que el sistema AP.">The SI treatment recorded similar (p> 0.05) cumulative emissions of CO2 and N2O during 146 days to the FP treatment. The cumulative CO2 emission was of 2780 and 2596 kg CO2 ha-1 under SI and FP, respectively, and cumulative N2O emission was of 273 g N2O ha-1 and 227 g N2O ha-1 for SI and FP, respectively. The lack of measurements of N2O immediately after the application of N, especially for FP, may have led to the underestimation of N2O losses. It is necessary to extend this type of research in the region, to contribute to the development of agronomic practices aimed at mitigating the effects of GHGs on the environment.
Parkin, T., A. Mosier, J. Smith, R. Venterea, J. Johnson, D. Reicosky, G. Doyle, G. McCarty, and J. Baker. 2003. Chamber-based trace gas flux measurement protocol. USDA-ARS GRACEnet. Available at http://www.usmarc.usda.gov/SP2UserFiles/person/31831/2003GRACEnetTraceGasProtocol.pdf, verified 10/5/13.