Clay soil is often hated by gardeners. It is heavy, sticky when wet, and hard to dig. However, from a biological standpoint, clay is a nutritional goldmine. Clay particles are highly charged and hold onto essential nutrients and water far better than sandy soils. The challenge is unlocking that potential.
The key to improving clay structure is organic matter. Adding compost, composted bark, and organic mulch feeds the earthworms and soil bacteria. As these organisms digest the organic matter, they create soil aggregates, creating tiny passages for air and roots to move through. Never dig wet clay, as this collapses the soil structure. Instead, apply a thick layer of mulch in autumn and let the worms do the work for you.