N2O and CH4 emissions from soils under conventional and no-till management practices in Goiânia (Cerrados, Brazil) - Agropolis Access content directly
Journal Articles Geoderma Year : 2007

N2O and CH4 emissions from soils under conventional and no-till management practices in Goiânia (Cerrados, Brazil)

Abstract

Nitrous oxide (N 2 O) and methane (CH 4) are important greenhouse gases (GHG) produced respectively by the naturally occurring microbial processes of incomplete denitrification or nitrification and methanogenesis. Tillage practices and climate affect the release of GHGs. No tillage (DMC) systems may increase CO 2-C fixation in soil but also N 2 O and CH 4 emissions. The aim of this article is to question whether the positive effect of a DMC system observed on carbon storage for the topsoil layer in Cerrado soils is offset or not by the N 2 O and/or CH 4 emissions. Two 5-year-old systems, tillage (disc on the first 15 cm called offset: OFF) and a direct-sowing mulch-based crop system (DMC) with an additional cover crop were studied during a cropping cycle. N 2 O and CH 4 fluxes are determined using a closed-chamber, N 2 O and CO 2 concentrations are measured at 3 depths (10-, 20-and 30 cm). No significant difference between treatments was observed for both gases (for emissions and concentrations). Soil N 2 O contents increase from surface to depth (30 cm) and range from 300 ppbv to 3 ppm for both treatments. Total annual estimated emissions of N 2 O range from 31 to 35 g N 2 ON ha − 1 year − 1 for DMC and OFF respectively which is low and corresponds only to 0.03% of the total N-fertilizer applied. Monthly means N 2 O emissions were strongly correlated to monthly means of N 2 O content at 10 cm depth (R 2 = 0.66) and seem to increase exponentially with monthly mean Water Filled Pore Space WFPS (0-10 cm layer) (R 2 = 0.33). CH 4 fluxes were very low as well: both treatment act as source of CH 4 (245 and 403 g CH 4-C ha − 1 year − 1 for DMC and OFF respectively. On a CO 2-C equivalent basis these results correspond to 4.1 and 4.7 kg CO 2-C ha − 1 year − 1 for N 2 O and to 1.9 and 3.1 kg CO 2-C ha − 1 year − 1 for CH 4 for DMC and OFF respectively. As a result, the carbon sequestration balance taking into account the CO 2 , CH 4 and N 2 O on a CO 2-C equivalent basis is in favour of DMC treatment considering that this treatment increases carbon storage originated from CO 2-C for the topsoil (0-10 cm) layer (350 kg C ha − 1 year − 1) in comparison with OFF treatment.

Domains

Soil study
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Dates and versions

hal-04302901 , version 1 (23-11-2023)

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Aurélie Metay, Robert Oliver, Eric Scopel, Jean-Marie Douzet, José Aloisio Alves Moreira, et al.. N2O and CH4 emissions from soils under conventional and no-till management practices in Goiânia (Cerrados, Brazil). Geoderma, 2007, 141, pp.78 - 88. ⟨10.1016/j.geoderma.2007.05.010⟩. ⟨hal-04302901⟩
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