PORE SPACE VARIABILITY IN A SUB‐SURFACE HORIZON OF TWO SOILS

Summary Image analysis was used to investigate the variability of pore space in soil thin sections. Two fine‐textured soil profiles (or pedons) were sampled by inserting eight Kubiena tins (7.5 × 6 × 4 cm) in ledges at 50 cm depth. From each soil block three horizontal thin sections (7.5 × 6 cm) were made and photographed. Each photograph was then divided into nine ‘frames’ so that the voids in each of these frames could be measured using the Quantimet 720 Image Analysing Computer. The results show the variability of three specific pore‐space characters and the consequent need to sample a number of large thin sections from several sample blocks for each soil horizon to obtain estimates of sample means with suitable accuracy.