N2O emissions from soils under different uses in the Brazilian Cerrado - A review

Abstract

The Cerrado (Brazilian savannah) is a biome of great socio-economic and environmental importance to Brazil. The rapid agricultural expansion in the Cerrado biome areas promoted biogeochemical cycles that affect nitrogen and carbon dynamics, leading to increased greenhouse gas (GHG) emissions. In Brazil, nitrous oxide (N 2 O) is the main gas in agriculture, and agricultural practices increase emissions into the atmosphere. This review aimed to assess the influence of agriculture on N 2 O emissions in the Cerrado region, based on existing data in the literature, and extract patterns of direct N 2 O emissions in different agricultural systems in the Cerrado from existing data. A systematic review of data from 36 scientific publications in the Cerrado region with several crop systems revealed that N 2 O emissions varied from 0.15 kg ha -1 in native cerrado to 4.84 kg ha -1 in conventional tillage. Agricultural systems, nitrogen fertilizer application, and crop residues influence N 2 O emissions. One of the strategies to mitigate emissions is the sustainable intensification of farming systems. Cumulative N 2 O emissions in the Cerrado range from 0.001 to 4.84 kg ha -1 in different land-use scenarios. Soil under the conventional tillage system (CT) had the highest emissions, with an overall average of 1.58 kg ha -1 of N 2 O, compared to no-till system (NT) (0.82 kg ha -1 ) and native Cerrado 0.15 kg ha -1 . Integrated crop-livestock (ICL) systems in the Cerrado had emissions with an overall average of 1.68 kg ha -1 , integrated crop-livestock-forest systems (ICLF) had 1.20 ha -1 , and eucalyptus plantations had 0.48 kg ha -1 .