Soil emissions of NO, N2O and CO2 from croplands in the savanna region of central Brazil.

Submitted by Maurílio Figueiredo (maurilioafigueiredo@yahoo.com.br) on 2012-06-19T16:55:19Z No. of bitstreams: 2 A7.pdf: 705434 bytes, checksum: 0c82af3b14e65c1146cef0782d646433 (MD5) license_rdf: 20325 bytes, checksum: c7f3e3c064c19e93e905bbb07856484c (MD5)Made available in DSpace on 2012-06-19T16:55:19Z (GMT). No. of bitstreams: 2 A7.pdf: 705434 bytes, checksum: 0c82af3b14e65c1146cef0782d646433 (MD5) license_rdf: 20325 bytes, checksum: c7f3e3c064c19e93e905bbb07856484c (MD5) Previous issue date: 2011-11In the last 40 years, a large area of savanna vegetation in Central Brazil (Cerrado) has been converted to agriculture, with intensive use of fertilizers, irrigation and management practices. Currently, the Cerrado is the main region for beef and grain production in Brazil. However, the consequences of these agricultural practices on NO, N2O and CO2 emissions from soil to atmosphere are still poorly investigated. The objectives of this study were to quantify soil emissions of NO-N,N2O-N andCO2-C in different no-till cultivation systems in comparison with native savanna vegetation. The agricultural areas included: (a) the maize and Brachiaria ruzizienses intercropping system followed by irrigated bean in rotation; (b) soybean followed by natural fallow; and (c) cotton planting over B. ruzizienses straw. The study was performed from August 2003 to October 2005 and fluxes were measured before and after planting, after fertilizations, during the growing season, before and after harvesting. NO-N fluxes in the soybean field were similar to those measured in the native vegetation. In the cornfield, higher NO-N fluxes were measured before planting than after planting and pulses were observed after broadcast fertilizations. During Brachiaria cultivation NO-N fluxes were lower than in native vegetation. In the irrigated area (bean cultivation), NO-N fluxes were also significantly higher after broadcast fertilizations. Most of the soilN2O-N fluxes measured under cultivated and native vegetation were very low (