An experimental device has been set up for ten years at the Kerguehennec Experimental Station (Chambre Regionale d'Agriculture de Bretagne) located in Brittany (western France) on the basis of a corn/wheat/rape/wheat rotation. The study, in the western context of France, compares three tillage practices (moldboard plowing, surface tillage and no-tillage) and two nutrient sources (mineral and poultry manure), each management systems repeated three times. The aim of this study was to evaluate the effect of reduced tillage and manure fertilization on the evolution of soil characteristics: porosity, aggregate stability, organic carbon, hydraulic conductivity and earthworm populations. The results show that treatments without plowing know a decline of global porosity on the layer 0-25 cm, particularly in the case of the no-till. Although the abundance and biomass of earthworms are increased in reduced tillage, the decrease of porosity is not compensated. The consequence is the decline of hydraulic conductivity, in the case of the no-till. Surface tillage seems to constitute the best compromise, because it maintains or improves the infiltrability thanks to the improvement of aggregate stability in the surface layer and the protection of soil surface by the presence of a mulch.
