A modelling study on mitigation of N2O emissions and NO3 leaching at different agricultural sites across Europe using Landscape DNDC

Due to cascading effects of reactive nitrogen, the development of adequate management options to maximize crop production and minimize environmental N losses is still challenging. We apply the LandscapeDNDC model to simulate soil micrometeorology, crop growth, N2O emissions and NO3 leaching of several arable and grassland systems across Europe. LandscapeDNDC predicts very well the measured mean daily N2O emissions across all sites (r2 = 0.99). For NO3 leaching, the model does correctly represent increases of inorganic N pools after fertilization events. A mitigation potential is assesed by Monte Carlo optimizations of the individual underlying multi-year agricultural management options (timings of planting and harvest, fertilization & manure applications and rates and residues management) in order to reduce N2O emissions and NO3 leaching while keeping observed yields. LandscapeDNDC coupled to Monte Carlo optimization successfully derived targeted management adaptations that reduce N2O emissions and NO3 leaching (in average by 21 and 31%, respectively) in arable lands under complex rotation practices without penalizing current crop yields. Likewise, average reductions of 55% for N2O emissions and 16% for NO3 leaching are estimated for grasslands. The reduction of N losses proportionally decreased environmental indexes such as yield scaled N2O emissions and NO3 leaching suggesting the need to enhance the use of N resources in European farming systems. The applied optimization approach could be useful also in the prognostic mode in order to predict optimal timings and fertilization options (rates and splitting) upon actual weather forecasts combined with the knowledge of modeled soil nutrient availability and plant N demand.