Compost Improves Soil Structure and Garden Fertility

Date:  March 24, 1997
Editor: D'Lyn Ford  (505) 646-6528, dlford@nmsu.edu

LAS CRUCES -- The ideal soil for backyard gardens is deep, well-drained and fertile, and contains plenty of organic matter. It also should retain moisture and be easily worked and relatively free of stones. A New Mexico State University horticulture specialist explains how to make the "perfect soil" in your backyard.

"Compost is a great way to improve the structure of almost any soil," said George Dickerson, with NMSU's Cooperative Extension Service. For sandy soils, compost will increase the water-holding capacity and retain more nutrients. On the other hand, compost will improve the aeration of a clay soil to help it drain better.

Compost also adds some nutrients to the soil. "Because these nutrients are in organic form, they are easier for the plants to use over a longer period of time," Dickerson said. Compost also contains humic acid, which helps make other nutrients in the soil more available to plants.

"Compost can act like a natural fungicide, especially if it's made from shredded wood wastes like tree limbs or bark," he said. "In early spring when seedling diseases can be a problem, fungi in the compost compete with disease organisms in the soil for water and nutrients."

Apply compost 2-3 inches deep across the garden and till it into the soil. "Commercial composts made from livestock manure or sludge should be applied at lower rates, not only because they are more expensive, but also because they tend to have a higher salt content," Dickerson said.

Compost contains a wide variety of nutrients but normally not enough to maintain good plant growth throughout the season, he said. "Applying 2 to 3 pounds of a 5-10-5 fertilizer per 100 square feet of soil will help get your garden off to a good start." Leafy crops like corn, broccoli or cabbage will require more nitrogen later in the season.

After tilling in compost, rake the seedbed smooth, removing any rocks or debris. Dig irrigation furrows with a shovel or prepare raised beds. "Raised beds warm up earlier in the spring and are preferred if you have shallow soil with poor drainage," Dickerson said.

Taking the time to improve your soil before planting can help you reap sweet success from your garden.