1. TADRUS Research Group, Department of Agricultural and Forestry Engineering, University of Valladolid, 47011 Valladolid, Spain
2. Food, Land and Agribusiness Management, Harper Adams University, Edgmond, Shropshire TF10 8NB, UK
3. Agriculture and Environment Department, Harper Adams University, Edgmond, Shropshire TF10 8NB, UK
4. International Department, Harper Adams University, Edgmond, Shropshire TF10 8NB, UK