Mixing plant species in cropping systems: concepts, tools and models. A review E. Malézieux, Y. Crozat, C. Dupraz, M. Laurans, D. Makowski, H. Ozier-Lafontaine, B. Rapidel, S. de Tourdonnet and M. Valantin-Morison Agron. Sustain. Dev., 29 1 (2009) 43-62 Published online: 15 March 2008 DOI: 10.1051/agro:2007057