Surface cracking and aggregate formation observed in a Rendzina soil,La Touche (Vienne) France

A one-cycle field wetting and drying experiment was conducted in order to observe pore space developed in a cultivated Rendzina soil due to surface cracking and to soil aggregate formation at 3-cm depth. Image analysis of 2D representations of pore size distribution and fractal analysis of the spatial distribution of the pores indicates that pore space due to surface cracking does not develop in the same manner as does that formed in the aggregation processes. Both pore-size distribution and fractal dimension vary in different ways at the soil–air interface and at 3-cm depth as drying progresses. Surface cracking occurs as a two-step process where total crack length increases until a maximum and then the cracks widen. Fractal dimensions appear to change as pore space develops. Pores developed when aggregates form show a more continuous process of development of pore sizes with a constant fractal dimension as porosity increases.