N 2 O EMISSIONS FROM A CULTIVATED MOLLISOL: OPTIMAL TIME OF DAY FOR SAMPLING AND THE ROLE OF SOIL TEMPERATURE

COSENTINO, V. R. N.; FERNANDEZ, P. L.; FIGUEIRO AUREGGI, S. A.; TABOADA, M. A.

REVISTA BRASILEIRA DE CIêNCIA DO SOLO

SOC BRASILEIRA DE CIENCIA DO SOLO

Lugar: Vicosa; Año: 2012 vol. 36 p. 1814 - 1819

0100-0683

The correct use of closed field chambers to determine N2O emissions requires defining the time of day that best represents the daily mean N2O flux. A short-term field experiment was carried out on a Mollisol soil, on which annual crops were grown under no-till management in the Pampa Ondulada of Argentina. The N2O emission rates were measured every 3 h for three consecutive days. Fluxes ranged from 62.58 to 145.99 g N-N2O m-2 h-1 average of five field chambers) and were negatively related (R2 = 0.34, p < 0.01) to topsoil temperature (14 - 20 oC). N2O emission rates measured between 9:00 and 12:00 am presented a high relationship to daily mean N2O flux (R2 = 0.87, p < 0.01), showing that, in the study region,sampling in the mornings is preferable for GHG.