Abstract :
[en] Our experiment aimed at studying the impact of long term tillage treatments – reduced tillage (RT) and
conventional tillage (CT), on CO2 and N2O emissions by soil and at describing the dynamics of N2O
fluxes.
Gas measurements were performed from June to October 2015 in a Belgian maize crop, with homemade
automated closed chambers, allowing continuous measurement at a high temporal resolution. After 7
years of treatment, CO2 and N2O average emissions were significantly larger in the RT parcel than in the
CT parcel. This observation was attributed to the effect of tillage on the distribution of crop residues
within the soil profile, leading to higher soil organic C and total N contents and a greater microbial
biomass in the upper layer in RT. A single N2O emission peak triggered by a sudden increase of water-
filled pore space (WFPS) was observed in the beginning of the measuring campaign. The absence of large
emission afterwards was most likely due to a decreasing availability of N as crop grew. N2O background
fluxes showed to be significantly correlated to CO2 fluxes but not to WFPS, while the influence of soil
temperature remained unclear. Our results question the suitability of reduced tillage as a “climate-smart”
practice and suggest that more experiments be conducted on conservation practices and their potent
negative effect on environment.
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