With household budgets under pressure and locally-grown foods all the rage, the backyard vegetable garden is making a comeback. Increasing numbers of Americans are discovering their green thumbs along with the bigger savings and better flavors of meals grown a few steps from their kitchens.

But eating backyard bounty is the easy part. It's the growing that can get a little tricky. As any experienced gardener will tell you, success is rooted in your soil.

Though many people view soil as mere "dirt," it is actually one of nature's greatest treasures. It's a complex mixture of minerals, microorganisms, fungi, organic material, water, and gases that combine to create a unique medium in which things both great and small can bloom. Without this living, breathing material there would be no forests, no fields, and no food upon our tables. The sun might shine and the rains might come, but in the absence of soil these elements would fall upon an empty, silent world.

There are 70,000 different kinds of soil in the United States. A single tablespoon can contain as many as 7,000 separate species of bacteria and hold more microorganisms than there are people on Earth. And if you think that's impressive, consider this: It can take nature up to 500 years to produce just a single inch of the stuff.

Soil is a precious commodity, and in your garden it's more than that. As the medium from which your plants will derive sustenance, it's the single most important factor in a plentiful harvest. Here are some ways you can make sure your garden soil stays healthy:

• Make sure your garden is in a location with good drainage. Rainwater should be able to move away from your soil leaving it moist but not oversaturated, a condition which can quickly degrade your soil's vitality.

• Skip the conventional fertilizers. These can contain so-called "biosolids," dried sewage sludge mixtures that can introduce heavy metals, synthetic chemicals, and other toxins into your garden soil. Commercial fertilizers also can be made from petroleum -- one 40-pound bag can contain the equivalent of 2-1/2 gallons of gasoline. These and other types of artificial fertilizers may give plants a quick jolt of super-charged nutrition, but their concentrated ingredients can also kill beneficial bacteria and sterilize your soil, which will leave you dependent on ever greater amounts of synthetic fertilizers.

• Instead, look for natural fertilizing products made from organic materials like manure and compost that say they are "NOFA Approved" and/or "OMRI Listed." Such products have been certified by the Northeast Organic Farming Association and/or the Organic Materials Review Institute (OMRI) and) to meet the USDA's organic standards.

• The best fertilizer for your garden is compost you make yourself. Compost, which consists of decomposed fruit and vegetable scraps, yard waste, and other natural biodegradable materials, is ideal food for the earthworms and microorganisms that keep living soil healthy. It also contains tremendous amounts of nutrients in forms that your plants are more easily able to absorb.

• Rotate your plantings from year to year within your garden space. Growing the same crop in the same spot each year reduces the biodiversity of your soil and gives harmful pests an advantage.

• Don't use chemical pesticides or herbicides. These may kill dreaded bugs and evil weeds, but they'll wipe out all your garden's beneficial insects and soil organisms, too. In the long run, your soil will be unable to support life -- and that includes the food you're trying to grow.

• Till as little as possible, and use gentle non-mechanical means like rakes and hoes instead of motorized rototillers. Tilling disrupts your soil's biotic communities, mixes living topsoil with less fertile soil buried beneath it, and removes vital carbon-based organic matter.

• Plant your crops in wide beds that will limit your movement within your garden and help prevent your feet from compacting your soil. The best soils are loose and crumbly, a state which allows vital oxygen, water and other elements to easily reach plant roots and soil organisms.

• Mulch your garden to help prevent soil from washing away, maintain moisture levels, and protect it from temperature extremes. If you use a high-carbon mulch like straw or dead leaves, take care not to mix this mulch into the soil as the microbes living there will "eat" up all the nitrogen your plants need as they attempt to break down the high levels of carbon these mulches contain. You can also mulch with compost, which many experts say is the best choice.

We'd love to hear your backyard gardening tips! Just reply to our blog post.

photo: Southern Foodways Alliance