Amending soil with organic matter key step in planting process

For years I have been recommending that when you plant trees, shrubs, bulbs, flowers or a vegetable garden it is important to amend the soil with organic matter, either compost or peat moss. A recent article in a nursery trade journal confirmed my recommendation.

If your soils have a lot of clay, organic matter amendments are a must to unlock the positive attributes of clays. As I'm sure you are aware, clay soils are sticky when wet, and as hard as a brick when dry. Few plants grow well on a clay soil.

The addition of organic matter to these clays will change the structure of the soil by causing the small clay particles to aggregate into larger particles. These aggregates will result in a soil that crumbles in your hand; the soils internal architecture has changed.

Because the organic matter has changed the orientation of the clay particles, there are lots of air spaces between the particles. These spaces fill with water after a good rain, and act as a storage facility for soil water. The result is a soil that is better drained, as well as a soil that has increased water holding and storage capacity -- the best of both worlds.

Clay particles in a soil also act as storage units for plant nutrients such as calcium, phosphorus and potassium. Under the right conditions, these nutrients are released to the soil solution and plants take them up as their roots take up soil water.

Gary Siebert adds organic compost and peat moss while planting an emerald arborvitae evergreen tree in Cape Girardeau. (Fred Lynch)

Organic matter is the nutrient source that soil microorganisms need in order to survive and grow. The role of soil microorganisms are extremely varied, but their importance cannot be over emphasized. Soil microorganisms enhance water and nutrient uptake into plants by forming a symbiotic relationship with plant roots.

If you have sandy soils in your area, addition of organic matter is a must for good plant growth and for economical applications of plant nutrients. Sandy soils have very little storage capacity for plant nutrients. Most fertilizer that is applied will leach through the sand upon irrigation or rain and will be lost to soil layers below the rooting depth.

Organic matter in the soil will store plant nutrients. These nutrients will then be made available when plants need them for rapid growth and development.

As you also know, sandy soils do not hold moisture well. Again addition of organic matter enhances the ability of sandy soil to hold moisture and release it when needed for plant growth.

Sandy soils are somewhat sterile. Addition of organic matter to sandy soils, as in clay soils, will provide a substrate upon which soil microorganisms will feed and grow.

With this information in mind, it behooves you to amend your flower bed and vegetable garden soils on a regular basis, preferably once every year or at least every other year. If you are planting trees and shrubs in areas where the soil will not be disturbed for several years, you should amend the soil when planting. Organic matter will enhance the survivability of your plantings, and will result in thriving plant growth.

Send your gardening and landscape questions to Paul Schnare at P.O. Box 699, Cape Girardeau, Mo. 63702-0699 or by e-mail to news@semissourian.com.