Evaluation of nitrous oxide emissions from vineyard soil: Effect of organic fertilisation and tillage

It is well known that the largest source of N2O is the agricultural sector, where fertilization represents the main source of this GHG. Monitoring N2O fluxes for different soil management and crops type is essential to define better N management practices in agro-ecosystems. However, scarce studies have been published about field measurements of organic fertilizers effects in orchards and vineyards.In this paper we present the first long-term high-resolution study on N2O emissions in a vineyard, in temperate climate. The use of dynamic chambers connected directly to an IRGA, allowed to collect one year (from May 2018 to May 2019) of measurements at time resolution of 2 h. The aim of the study was to assess the effect of organic fertilization (compost) and tillage on N2O emissions. Emission factors of uncorrected (EFt) and corrected for no-fertilizer induced emissions (EFf) were calculated.Results showed a seasonal trend in N2O fluxes, with higher base fluxes and peaks during the warm season and in correspondence of rainy events. Emission peak linked to fertilizer application occurred during the first 6-7 days after treatment followed by a decrease in N2O fluxes. Cumulated annual emissions varies between 0.54 and 1.38 kg N2O-N ha-1 y- 1, depending on treatment and level of soil TOC content. The uncorrected EF was between 0.4 and 0.9% of N input, in line with the IPCC value for organic fertilizers in wet climate, while the EFf (referred only to direct fertilizer application) were in range of 0.02-0.4% of N input. We found EFf of fertilized not tilled treatments from 17 to 79% lower than fertilized tilled, with different magnitude of reduction depending on soil TOC. Our EFt were in line with disaggregated EFs from IPCC 2019 but EFf were 43% lower on average, con-firming the IPCC reference value to be a good estimator of the overall N2O emissions from organic fertilized soil, but too high for the estimation of only fertilizer application emissions.These results are of remarkable importance to direct organic fertilization management and related policies towards more environmentally sustainable approaches.