1. Department of Agroecology, Research Centre Foulum Aarhus Univ. Blichers Allé 20, P.O. Box 50 Tjele DK‐8830 Denmark
2. Department of Mathematics Applied Statistics Laboratory Aarhus Univ. Ny Munkegade 118 Aarhus Denmark
3. School of Agriculture, Food & Wine, Waite Research Institute The Univ. of Adelaide PMB 1 Glen Osmond SA 5064 Australia
4. Departamento de Ciências Agrárias Univ. Tecnológica Federal do Paraná Via do Conhecimento, km 1 Pato Branco PR 85503‐390 Brazil