Originally created 12/16/05

Keep garden soil at its best with compost



Compost is certainly a hot item when it comes to gardening. When you read the latest garden articles, watch your favorite gardening program on television, listen to the Saturday morning lawn and garden radio show, or talk to your extension agent, you know its use is enthusiastically touted.

I believe we can get all gardeners to agree that compost is good for the garden, especially in the Augusta area since we are not blessed with the best natural soil conditions. But why is compost good and how should it be applied?

Compost is what is left of organic matter after microbes have thoroughly decomposed it. Simply put, it's decayed organic matter. Through the composting process, plant materials are broken down into smaller particles. The final product has an organic-matter content of around 35 to 45 percent and resembles potting media.

Because it's high in organic matter and doesn't contain "synthetic" chemical fertilizers, compost is a good source of organic fertilizer. Generally speaking, organic fertilizers come from plants or animals that took up these nutrients, or fertilizer elements, and chemically bound them in their tissues and byproducts.

Because they're integrated into complex organic molecules, the plant nutrients in organic fertilizers are in relatively low concentrations. They're not water soluble, and they're not readily available. They have to be broken down by organisms in the soil before the bound nutrients are released for plant roots to take up.

This keeps the nutrients from being washed out of the soil by heavy rains. It results in its slow release over many weeks or even months.

The nutrient content of compost varies with the materials composted and the specific composting process. Generally, it falls within these ranges: nitrogen, 1 to 2 percent; phosphorus, 0.2 to 1 percent; potassium, 0.5 to 1.5 percent; and calcium, 0.05 to 2 percent.

Besides these major nutrients, compost also contains small amounts of micronutrients such as boron, copper, manganese and zinc.

Remember, organic fertilizer is slowly released. It usually works best as a supplement to conventional fertilizer, not a replacement.

Compost, though, does more for the garden than just provide organic fertilizer. It also helps:

- Increase the soil's capacity to hold water and nutrients.

- Improve drainage in heavier clay soils.

- Reduce soil compaction, allowing more air and water to move among the soil particles.

- Improve the soil's tilth, or structure, making it easier for roots to grow and thrive there.

Eight to 10 weeks before you plant, broadcast compost over the garden. Any amount is helpful, but for best results, initially apply 20 to 30 pounds of compost per 100 square feet of garden soil. Scatter it uniformly over the entire garden.

For the best results, immediately after you spread the compost in the garden, till it into the top 8 to 10 inches of soil. To keep a good thing going, follow up the initial application each year with 10 to 15 pounds of added compost per 100 square feet.

Compost will help give you your best garden ever. By growing in a garden with good compost, your plants will grow better and be less susceptible to both insects and diseases. It will help you have a richer, more rewarding garden experience.

Sid Mullis is director for the University of Georgia extension service office for Richmond County. Call him at 821-2349, or send e-mail to smullis@uga.edu.