Healthy soil is essential for successful gardening, particularly if you garden according to organic principles. To the uninitiated, one lump of soil looks pretty much like another, hut it is in fact made up of varying quantities of rock, organic matter, water, air, and microorganisms.
The basic mineral composition of the soil will determine its fundamental character, but the quantity of organic matter it contains will influence its fertility —soil with no organic matter would be incapable of supporting plant life. Equally important to plant health are moisture and oxygen: soil that has been compacted (for example, by heavy machinery) loses its oxygen content, and the plants’ roots will suffocate.
The gardener’s aim is to create a soil that has a good, crumbly texture, with plenty of organic matter, and to ensure that there is an adequate amount of water. Be careful not to compact the soil by tramping over beds you have dug.
Whether your soil is made up primarily of sand, silt, or clay (the principal mineral ingredients) is determined by local geology. You can do nothing to influence this characteristic, but you can affect the soil’s ability to retain moisture or to drain by adding the right material. Adding organic matter to sandy soil will enable it to hold moisture better; grit and organic matter added to clay will improve its oxygen-retaining qualities— without these additions, the particles stick together in a gluey mass. To discover your soil’s type, you can conduct some simple tests.