Single-grain structure has somewhat the same appearance, but on the smaller scale of individual sand grains. Granular structure has a predominance of macropores, and bulk density is low. Most roots occur in the large pores at the corners of blocks and within the planar channels between the smooth faces of the peds. Some fine roots may penetrate the peds by following fine pores. As I discussed for medium-textured soils, greater resistance to water movement and root penetration occurs here as compared to granular structure, but the conditions are still favorable for good plant growth.
Conditions are more restrictive for roots.
Obviously, root penetration direction, water and gaseous movement tends to be at right angles to the axis of the long horizontal pores. This impedes gaseous diffusion and thus has a detrimental effect on root growth. On the other hand, most of the moisture drains from a sandy soil in response to gravity. Subangular blocky and blocky structure in a medium to medium-fine textured soil have intermediate conditions of drainage and water retention. The sampling tool is completely assembled here.