Soil tillage likely dates back to the same time as sedentarization of human societies during the Neolithic age, as the need arose to transform the natural environment to allow for agricultural activities. Tillage is a very effective technique for increasing the porosity of the soil by fragmenting the soil into structural elements of various sizes. Soil structure describes the way in which the different particles that constitute the solid phase of the soil are arranged in physical space. The structure of natural soils is the result of their pedogenesis, which involves mechanisms of rock weathering, in conjunction with the climate, the topography and the living organisms that are present. The effect of tillage on hydraulic conductivity is different from its effect on water retention. During the conversion of a cultivation system from conventional agriculture to conservation agriculture, a progressive densification of the soil layer initially tilled can be observed.