Gasvormige emissies na toediening van vergiste mest op grasland = Gaseous emissions after the application of digested manure to grassland

De landbouw is een belangrijke bron voor ammoniak- (NH3), geur- en overige broeikasgasemissies (CH4 en N2O) in Nederland. Ongeveer 80% van de totale NH3 uitstoot uit de landbouw is afkomstig vanuit bronnen uit stallen en bij het aanwenden van mest. Deze twee bronnen spelen ook een belangrijke rol voor geurhinder in Nederland. De landbouw is verantwoordelijk voor ongeveer 8% van alle broeikasgasemissies in Nederland. De doelstelling van dit onderzoek was de emissies van NH3, geur en broeikasgassen bij toediening van vergiste mest en van gangbare (onvergiste) mest met elkaar te vergelijken. Er zijn drie experimenten uitgevoerd. Per experiment werden twee proefvelden (diameterThis report shows the results of three experiments performed to study the effect of digestion on the emissions of NH3, odour and greenhouse gases (N2O, CH4, CO2) after slurry application on grassland soils. The digestion process resulted in an increase of the pH (by 8-10%) and the NH4+-N (by 6-25%) of the slurry for all three experiments. The dry matter and organic matter content of the slurry was lower in the digested slurry compared to the conventional slurry in the first two experiments (dry matter: 32-61% lower; organic matter: 36-64% lower). In the third experiment, differences in dry matter content between both slurries were not significant. The application of digested slurry resulted in higher NH3 emissions (a factor 1.9 in experiment 1, a factor 1.5 in experiment 2) compared to conventional slurry during the first two experiments. For experiment 3, due to the lack of wind during the night of the first day after the application of the slurry it was not possible to calculate accurately the cumulative emission from the plots. The cumulative NH3 emission was in general high when compared to previous measurements reported in the literature for experiments using shallow injection. No effect was found of digestion on the emissions of odour and greenhouses after slurry applicatio