ABSTRACT
The growing tip of the root wriggles through the growing medium following the line of least resistance. Roots are able to enter cracks that are, or can be readily opened up to, about 0.2 mm in diameter, which is about the thickness of a pencil line. Compacted soils severely restrict root exploration but once into these narrow channels the root is able to overcome great resistance to increase its diameter. Anything, which reduces root exploration and activity, can limit plant growth.When this happens action must be taken to remove the obstruction to root growth or to supply adequate air, water and nutrients through the restricted root volume.
