 My name is Marek van Wijk. I'm from Wageningen University and work with Plant Production Systems. I'm here to present modelling work we have been doing in the past. And we hope that the modelling work can contribute towards the goals of SOP and especially towards the quantification of the trade-offs between the uses of crop residues. So either you can incorporate them into the soil and maintain soil fertility or you can feed them to the cattle and then boost cattle productivity. The models I presented can really quantify the consequences of certain decisions. So they won't be able to identify new strategies or new technologies that can be implemented but really to quantify what will happen if a certain strategy is implemented. So the models we are using are really for researchers and then the outcomes can be summarized or sort of translated into indicators we can present to policy makers. What we try to use are summary models because data availability in the systems we are dealing with here in the SOP project is really an issue. So we try to keep them as simple as possible without losing of course all the main characteristics and the main problems that are playing in the different sites.