Solving special problems
Improving soil structure is important, but you may also need to correct other problems if your garden is to thrive. Soil may drain poorly; it may be too acid or alkaline; it may suffer from chlorosis or excess salts, or be underlain by a cementlike layer of hardpan.
Poor Drainage
Poor drainage causes myriad problems. If water simply stands in the soil’s pore spaces rather than draining away, there’s not enough air available for roots and beneficial soil-dwelling microorganisms, and both may die. The reduced root structure can’t adequately support the plant’s leaves and stems, and the resulting stress makes the plant more susceptible to insect infestation or disease. Below ground, molds develop and the normal balance of fungi is disrupted–and the weakened root structure is more prone to invasion by water-mold fungi.