1. a Flemish Land Agency , Department of Land Management , Gulden‐Vlieslaan 72, 1060 Brussels, Belgium
2. b Alterra Green World Research , Wageningen University and Research Centre , P.O. Box 47, 6700 AA Wageningen, Droevendaalsesteeg 3, Wageningen, The Netherlands
3. c Katholieke Universiteit Leuven , Laboratory for Agricultural Machinery and Processing , Kasteelpark Arenberg 30, 3001 Leuven, Belgium