Variação diária da emissão de metano em solo cultivado com arroz irrigado no Sul do Brasil

Abstract

2049Variação diária da emissão de metano em solo cultivado com arroz irrigado no Sul do Brasil .

Diurnal variation of methane emission from a paddy field in Brazilian Southeast

“…These values are near to the range of 50 to 130kJ mol -1 reported by Neue & SASS (1994). COSTA et al (2008) reported Ea values in the range of 59 to 341kJ mol -1 in a conventional planting system in South of Table 1 -Average and ranges of air, water and soil temperatures at 2 cm, 5 cm and 10 cm of depth, and average methane emission rates observed in the 24h-campaigns in three growing seasons of flood-irrigated rice cropping, calculated by a curve fit to local regression model. The error corresponds to 95% confidence interval of the adjusted curve.…”

“…In order to optimize efforts for gas measurements it is important to know the time representing the average daily emission for a given producing area, as well as the influence of some key environmental parameters associated with the emission fluxes, for example, soil, air and water temperatures. A number of studies reported positive correlations between CH 4 diurnal emission variations and soil temperature in paddy fields under different climate conditions (SCHüTz et al, 1990;YagI & MINaMI, 1990;SASS et al, 1991;COSTA et al, 2008). WANG et al (1997) argued that diel patterns of CH 4 emissions are determined by the interaction of the soil temperature and the partial pressure of CH 4 .…”

A seven-year study on the effects of fall soil tillage on yield-scaled greenhouse gas emission from flood irrigated rice in a humid subtropical climate

“…Each chamber top had a rubber septum sampling port, a stainless steel thermometer, and three battery operated fans to circulate and homogenize air within the chamber (Banker et al, 1995). Chamber closing and initial air sampling started at 9:00 am and were followed by five air samplings 5 min apart (Costa et al, 2008;Minamikawa et al, 2012). Air was drawn with polypropylene syringes, brought to the Laboratory of Soils and Biogeochemistry at UFRGS and analyzed for CH 4 and N 2 O concentrations on the same day with a Shimadzu (Shimadzu Corp.) gas chromatographer.…”

“…The flux rate of GHG from air sampling at 9:00 am were assumed to be equivalent to mean daily flux rate (Costa et al, 2008). Gas production rate was subsequently converted to kg CH 4 ha À1 d À1 and g N 2 O ha À1 d À1 .…”

Emissão de gases do efeito estufa em diferentes usos da terra no bioma Cerrado

“…A quantidade de N 2 O produzido em sistemas agrícolas é determinada pela disponibilidade de NO 3 - (Bouwman, 1996;Brown et al, 2000;Maggiotto et al, 2000), temperatura (Castaldi, 2000), pH (Daum & Schenk, 1998;Mogge et al, 1999), umidade (Zheng et al, 2000;Dobbie & Smith, 2003), além do material orgânico prontamente decomponível e das condições limitantes de difusão de O 2 (Mosier et al, 1991 Nesse contexto, o crescimento do setor agropecuário com a conversão da vegetação nativa em diferentes formas de uso da terra, é necessário conhecer as fontes emissoras dos GEE a fim de colaborar com um diagnóstico mais exato para as tomadas de decisões mitigadoras do aquecimento global. Contudo, a maioria dos estudos envolvendo o fluxo desses gases do solo para a atmosfera estão concentrados na região Sul do Brasil, comparando sistemas de cultivos (La Scala Junior et al, 2001;Costa et al, 2008a;Jantaia et al, 2008;Barreto et al, 2009;Gomes et al, 2009;Siqueira Neto et al, 2009;Escobar et al, 2010) e o fluxo de CH 4 em cultivos de arroz irrigado por inundação (Agostinetto et al, 2002;Costa et al, 2008b), assim como na Amazônia, comparando a transição floresta-pastagem (Steudler et al, 1996;Mellilo et al, 2001;Garcia-Montiel et al, 2002;Fernandes et al, 2002;Passianoto et al, 2003;Carmo et al, 2005;Neill et al, 2005;Wick et al, 2005).…”