Garden Soil Improvement

It has to be said that time spent improving your garden soil will never be regretted. But "improvements" does not mean the same thing to all gardeners. Therefore I will outline what should be done to soil and what can't and should not be attempted.

Generally, while soil structure can be changed, soil texture cannot. Texture is an expression of the relative amounts of sand, silt and clay particles that the soil contains. Many tons of sand can be added to your garden soil, but it will be, to use a familiar metaphor, just a drop in the ocean.

Soil structure however, expresses the manner in which these particles are associated with organic matter or humus to produce a blend of larger, pellet like crumbs with holes or pores between. By adding organic matter, you can increase both the number of pores and pores, a process that paradoxically will increase the moisture retentiveness of a free draining sandy soil just as readily as it will improve the drainage of a heavy clay.

Organic matter can be added to soil as a surface mulch, a beneficial enough process in itself that cuts down water loss through evaporation and suppresses weed growth. In due course, worms will drag down the surface mulch into the body of the soil. But as a method of adding large quantities of organic matter, double digging is far more efficient, although this can only be done in advance of planting, not among established shrubs and bushes.