Getting Down and Dirty with Dirt, Part 2 - Improving Your Soil Getting Down and Dirty with Dirt, Part 2 - Improving Your Soil
Almost any organic material can be added to soil. However, whatever is added will change the consistency, pH level, and water retention ability of the soil. For this reason, add wisely or else you could be contributing to the problem rather than reducing it. Here is a description of some of the more common organic materials that can be added.
Bark: Shredded bark can be alkaline or acidic depending on the type of tree it comes from. If it came from a hardwood tree, it will be slightly alkaline, good for suppressing weeds, and will not wash away easily. Most deciduous and tropical trees are considered hardwoods. If the bark came from a softwood tree, it will be more acidic. It also is likely to float away if there is enough rain and has been known to attract insects. Pine, firs, redwoods, spruce, cedar, larch, hemlock, cypress and yew are examples of softwood trees. In general, both types of shredded bark will decompose slowly.
Grass Clippings: Grass clippings decays rapidly and adds nitrogen to the soil. They can also help prevent weeds and helps the soil retain moisture. Only use clippings from lawns that have not been treated with herbicides.
Hay and Straw: "City folk" rarely understand the difference between hay and stray. Straw is the dry stalk of wheat, oats, rye or barley after the grain has been removed. In comparison, hay is dried grass, clover or alfalfa. Hay does not make good mulch material because it is more expensive than straw and is usually full of weed seeds. Straw is much cheaper and decomposes rapidly.
Leaves and Leaf Mold: Leaf mold is created by composting leaves. If you begin mulching your leaves in the fall, they will be ready to use by the spring. It can also be purchased from many municipal composting facilities. If you decide to use leaves without composting, it is best to shred them first to keep them from blowing away.
Manure: Manure can be readily obtained from any stable or farm. Of course, it can also be purchased at any lawn and garden store. Allow it to partially compose, or age, before using.
Oyster Shells: Oyster shells are good additions to clay soil because it will raise the pH levels and provide calcium.
Peat Moss: This will lower the pH level of soil and make it more acidic. However, it is expensive and can be tends to shed water once it has dried. It will also encourage shallow rooting, making plants less likely to tolerate any droughts.
Pine needles: Pine needles will make soil more acidic. It also has the added benefit of allowing water to penetrate.
Sawdust: Sawdust decomposes slowly and can help improve the quality of clay and sand. Fresh sawdust could use up large quantities of nitrogen as it decomposes. Also, some sawdust can be very acidic.
Wood Ash: This will raise the pH level of acidic soil making it more alkaline. It is also a great source of potassium and readily found in any fireplace. It should be avoided with clay soils because it will only make them heavier.
Wood Chips: Wood chips can actually remove nitrogen from the soil because they decompose very rapidly. They also attract termites or other insects. While a two-inch layer of wood chips on top of the soil is good for preventing weeds, it could be robbing the plants of nutrients unless a nitrogen fertilizer is used.