Vian, Jean François; Peigné, Joséphine; Chaussod, Rémi and Roger-Estrade, Jean (2007) Assessment of tillage systems in organic farming: influence of soil structure on microbial biomass. First results. 3rd QLIF Congress: Improving Sustainability in Organic and Low Input Food Production Systems, University of Hohenheim, Germany, March 20-23, 2007.