5 tricks for healthier, richer garden soil

Soil is very much alive, and it constantly changes as plants come and go, taking up nutrients and leaving behind their remains. Find out what makes for healthy soil and what you can do to enrich your garden soil.

Soil is made up of inorganic particles—sand, silt and clay—as well as organic matter, air and water. It is also home to numerous insect larvae and beneficial fungi and bacteria.

• A soil test will tell you how your soil rates in terms of fertility, as will plant growth; plants that grow slowly and never reach the size they should are a clear indication of low soil fertility.

• Their makeup includes large sand particles, small clay ones and in-between–size ones called silt.
• Most importantly, excellent soil contains plenty of organic matter. When the balance is close to perfect, the soil is called fertile loam.

To test your soil's texture, rub a pinch of moist soil between your thumb and forefinger.

• Soil that is too sandy feels gritty and will crumble.
• Silty soil feels smooth and slick, while clay soil feels sticky and rolls up easily.
• Good garden loam may contain about 50 per cent sand, 25 per cent silt, up to 25 per cent clay and five to 10 per cent organic matter.

Drop a spadeful of moist soil on a hard surface; if it breaks into crumbs one centimetre (half an inch) in diameter, its organic matter content is close to ideal.

• If it breaks into large clods or shatters into a sandy pile, it needs substantial amending.

The single most important way to improve all soils is by adding organic matter.

• Work three to 10 centimetres (one to four inches) of rotted manure, compost, chopped leaves or other organic matter into the soil each year to turn any type of soil into fertile garden loam.
• Dig as deeply as possible, because digging or deep tilling aerates the soil. Beneficial soil micro-organisms need oxygen to break down organic matter and release nutrients.

• To avoid squeezing out the air pockets and pushing particles together, don't walk on, work in or drive machinery over soil when it's wet.
• Neither air nor water can move through tight, compacted soil.

If you're new to an area, talk with gardening neighbours or regional master gardeners to find out if fusarium, verticillium or nematodes are prevalent in your area.

• If they are, choose plant varieties that offer genetic resistance to these diseases, because it's impossible to rid the soil of them entirely.

Some leafspot diseases overwinter in soil so they can be spread to leaves when soil is splashed on foliage during heavy rains or routine watering.

• Use a soaker hose or drip irrigation and water only in the morning, so leaves can dry off quickly.
• Use mulch, which forms a barrier between the soil and plant leaves.

Heating soil with solarization (covering it with a clear plastic tarp) can rid it of weeds, insect and disease problems as well as soil-dwelling nematodes.