Adding organic material improves soil

CORVALLIS – Adding organic matter is the best way to improve nearly all kinds of soils. If you’re unsure if your soil needs amendments, take note if it dries and cracks in summer, drains slowly or is difficult to dig whether wet or dry.

Adding organic materials improves the ability of sandy soils to hold nutrients and water, according to Weston Miller, Oregon State University Extension Service horticulturist. For clay soil, organic additions improve drainage and aeration and help the soil dry out and warm up more quickly in the spring.

The best soil amendment is partially broken-down organic material, better known as compost, Miller said. You can make compost at home or buy it. Finished compost is available in bags at plant nurseries and home improvement centers.

Follow these guidelines to add the right amount of compost to your site for growing vegetables.

For existing garden beds, apply a layer of compost, a quarter-inch to 1-inch deep, to the bed surface each year. Add other amendments such as lime and N-P-K fertilizer as needed. Incorporate the materials into the top 8 to 12 inches with a digging fork or spade. Or, use a rototiller.

When filling framed raised beds enclosed by retaining walls, use a soil mix. Don’t fill them with compost by itself. Add compost to soil before you plant. Spread a 3- to 4-inch layer of compost over the area you intend to plant. Mix the compost into the soil as deeply as possible. Then install new plants into the amended soil.