Título:	Methane emissions from a flooded rice field in the south of Brazil.
Autoria:	COSTA, F. de S. LIMA, M. A. de BAYER, C. FRIGHETTO, R. T. S. BOHNEN, H. MACEDO, V. R. M. MARCOLIN, E.
Afiliação:	F. de S. COSTA; MAGDA APARECIDA DE LIMA, CNPMA; C. BAYER; ROSA TOYOKO SHIRAISHI FRIGHETTO, CNPMA; H. BOHNEN; V. R. M. MACEDO; E. MARCOLIN.
Ano de publicação:	2003
Referência:	In: INTERNATIONAL METHANE AND NITROUS OXIDE MITIGATION CONFERENCE, 3., 2003, Beijing. Proceedings... Beijing: China Coal Information Institute, 2003. p. 190-197.
Conteúdo:	The State of Rio Grande do Sul in Brazil cultivates about 1Mha of rice in paddy fields. The soils are prepared using either conventional tillage (CT, 41% of the area) or no tillage (NT, 14% of area), the remaining falling in a mixed soil-preparation category. The outcomes of the current study represent the first evaluation of CH4 emissions from flooded rice fields in the south of Brazil. This information will feed the Brazilian greenhouse gas inventory. The study was carried out from January through March 2003 at the IRGA experimental station located in the municipality of Cachoerinha, Rio Grande do Sul, Brazil. Rice has been cultivated in this Gleisol area since 1994 using either the CT or NT system. The closed chamber method was used to collect air samples from 9:00 AM to 12:00 Noon on a weekly basis or in 24-hour campaigns; samples were analyzed using gas chromatography. Soil and plant parameters were also measured in order to determine which ecosystem factors affect CH4 emissions from the soil into the atmosphere. Along the period, CH4 emission rates varied from 24 to 703 mg m-2 day-1. NT plot emissions were initially greater than those from the CT plot, probably due to having maintained the crop residues on the surface of soil in the NT system. Nevertheless, CH4 emission rates in the CT plot were higher than in the NT plot 14 days after flooding, probably due to the higher root mass in the deeper soil layer in the NT system. The close relationship (P<0.01) found between CH4 emissions and soil temperature in both systems explains 60% of CH4 emissions. Total CH4 emissions were 33 and 22 g m-2 in the CT and NT systems, respectively. The emission variation between the soil preparation systems corresponds to 2,860 kg ha-1 CO2 equivalents. Moreover, this reduction represents 0.8 Mg ha-1 yr-1 C equivalents, greater than the average value of 0.58 Mg C ha-1 year-1 for C sequestration in agricultural soils in the subtropical region of Brazil. The 24-hour campaign emissions produced a sigmoid curve into both the atmosphere and the chamber, albeit with an inverse relationship. The 24-hour emissions were controlled by the soil and flood-water temperatures.
Thesagro:	Arroz Metano
Tipo do material:	Artigo em anais e proceedings
Acesso:	openAccess
Aparece nas coleções:	Artigo em anais de congresso (CNPMA)