Organic matter (OM) is garden gold. It helps increase the ability of a soil to absorb and store water. In porous, sandy soils, adding OM slows water movement through the soil, increasing the soil’s water‐holding capacity. In soils with lots of clay, the addition of organic matter helps loosen the soil, improving or increasing water infiltration and drainage. Organic material also acts as a holding station for plant nutrients, keeping the nutrients in the soil making them slowly available for plant use. It further reduces the potential for nutrient pollution to groundwater and surface water. Finally, it improves air penetration keeping roots healthy.
Organic material soil amendments come in many forms. Composted organic material is the best. Composting breaks down the organic components into a simpler nutrient form, humus, that is more available to plants. Uncomposted materials actually use plant nutrients during their breakdown in soil, robbing plants of these nutrients. Composting also generally decreases many potential problems, such as diseases, insect eggs and larva and weed seeds. Some uncomposted materials, such as manure, may add or transfer diseases, such as E. coli and viruses, and weed seeds that pass through the animals. Depending on the species of animal, adding uncomposted manure also may damage your plants or seeds due to high levels of nitrogen and salts. Poultry, horse and cow manure will often damage or “burn” plants if it is not composted or well‐rotted.
Last week my colleague, Melody Hefner wrote that good soil is alive with all kinds of organisms (biota) from beneficial fungi and bacteria to worms and insects. OM loosens up the soil giving all these organisms a healthy place to live. It provides them with food too. In turn, these beneficial critters decompose remaining OM and leave their castings as nutrients for plants.
Where does a gardener get OM? You can collect it on your own property. Each autumn I collect the leaves that fall off the trees and stockpile them over the winter. Winter precipitation starts the breakdown process and I then use this material around trees and shrubs in the spring as mulch rather than as a soil amendment. Mulch goes on top of the soil and soil amendments get worked into it. However, running a lawn mower over the dry leaves in the fall chops them up nicely. The chopped up bits work much better as a soil amendment than whole leaves. Or, the chopped leaves can be added to a compost pile. Compost is great OM. Lawn clippings are another organic material and are also a great addition to a compost pile. You can chip prunings, collect vegetable material, coffee grounds and eggshells from the kitchen and add them to the compost pile too. Straw and pine needles are organic material too but break down slowly with few nutrients. Of course, compost can also be purchased either in bags at nurseries or in bulk by the truckload.
Build a living soil for thriving plants this year. Add decomposed organic matter.