Impact of vineyard cover cropping on carbon dioxide and nitrous oxide emissions in Portugal

Özet

Scarce studies have been published reporting field measurements of nitrous oxide (N2O) emissions fromvineyards, particularly for European conditions. The aim this study was to assess the effect of conventionaltillage and no-tillage cover crops on direct N2O emission factor from vineyards (Vitis vinifera L.) inPortugal. A two-year field study was carried out in central Portugal (Nelas, Portugal). The experiment wasestablished in a mature non-irrigated vineyard. The following four treatments with three replicationswere considered: soil tillage of the inter-row (Till), treatment Till followed by application of mineralfertiliser (50 kg N ha-1) (Till þ N), permanent resident vegetation in the inter-row (NoTill), and treatmentNo-Till followed by application of mineral fertiliser (50 kg N ha-1) (NoTill þ N). The carbon dioxide (CO2)and N2O fluxes were measured by the closed chamber technique and analyzed by gas chromatographyduring two consecutive growing seasons (March-September of 2015 and 2016) of the grapevine crop. Theresults showed that the average direct N2O EF for vineyards managed with conventional soil tillage in theinter-row was 0.57 ± 0.12% of N input and cover cropping by permanent resident vegetation in the interrowreduces N2O emission in 60% (0.23 ± 0.29% of N input). Thus, the vineyard cover cropping wasrecommended as mitigation measure in order to reduce N2O emissions. The defaults direct N2O EFcurrently recommended by IPCC was not appropriated for vineyards and N2O emissions are currentlypotentially overestimated in the Portuguese inventory.