The LANDSUPPORT BEST PRACTICE tool to identify the trade-off between soil health and crop production

The LANDSUPPORT IT group has developed the web-based "Best Practices tool" that runs on the fly to identify optimized solutions for enhancing crop production and soil fertility while reducing nitrate leaching. The tool applies a what-if scenario approach at regional scale in three case studies (Marchfeld - Austria, Campania Region - Italy, Zala County - Hungary). The target users are public authorities, such as regional environmental agencies, to find the best solutions according to a goal to be pursued in a given region of interest (ROI). The tool is dy- namically linked to the ARMOSA process-based model, which simulates at daily time step combinations of farming systems (conservation, organic, conventional), crops, nitrogen fertil- ization rates, tillage solutions, crop residues management. The tool outcomes are the mean annual value of (1) the crop yield, (2) the nitrate leaching at the bottom of the soil profile, and (3) the change of the soil organic carbon stock in the upper soil layer (0-0.3 m). The tool also returns the value of the "best practices index" (IBP) that is computed as a linear combination of the three variables and the weights that the user dynamically assigns to each of the variables according to the specific goal (e.g., increase in soil organic carbon). The user then sorts the IBP values in descending order to identify the most suitable combinations of practices. The mean value of IBP is plotted in charts for each of the simulated combinations. How does the tool work? The user sets up the combination of agronomic practices via web interface in a given ROI, whose soil properties are dynamically used by ARMOSA as input data. The possible combinations are many (up to 2520 combinations): 5 climate scenarios specific, 7 crops, 2 systems (conventional, organic), 3 fertilization rates (optimal amount, 15% and 30% reduction), 2 residues management (removal, retention), 3 tillage practices (ploughing, mini- mum tillage, sod seeding), and 2 uses of cover crops (yes, no). The user-friendly interface hides the high complexity of the soil and crop processes which are simulated on the fly by ARMOSA, which has many crop and soil parameters already calibrated using the dataset available in the project and in previous studies. The close link with ARMOSA allows the tool to represent actual and optimized cropping systems with the possibility of further applications in other regional case studies and in tailored scenarios uploading soil properties and climate data with a bot- tom-up approach.