Ensuring healthy soil

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Good soil is the foundation on which you build a garden. A large portion of growth activity in plants goes on underground, so poor soil not only affects the growth of plants but can indirectly influence the health of plants. Weak plants are far more susceptible to disease and insect attacks.

Soil, top soil, growing medium or whatever you want to call it, has three major characteristics. There is the physical nature of the soil, chemical elements in the soil and the bacterial life present. All three must be in balance to provide a healthy growing environment.

Most soil consists of three materials, clay, silt and sand. Soil with a high percentage of clay, the finest particles, may be reasonably fertile but drains poorly, is difficult for roots to penetrate and contains little oxygen. Silt soil has slightly larger particles but performs much the same way as clay soil. Sand is the largest of the three particles, so sandy soil can drain quickly and more oxygen can penetrate the soil. Most quality top soils have a mixture of these three components and are named by the material that is dominant. For example, clay loam, silt loam or sandy loam. The organic matter or humus in top soil is considered to be an amendment to the soil.

For good growth plants must have access to carbon (CO2), hydrogen (H2O), oxygen (O2) and 13 other elements. These elements may be in the soil or added as amendments in the form of chemical or organic fertilizer. Chemical fertilizers are very concentrated and often quick to release. This is why they can cause problems if not used properly. The concentrate can kill microbes that are needed to convert fertilizer into plant food. Organic fertilizers are generally not concentrated and are slow to release. However, it may take a pail full of compost to equal a handful of chemical fertilizer. In a rainy climate some of the elements are prone to leach out of the soil. A soil test will determine which elements are deficient.

Unlike testing for fertilizer elements, it is not easy to determine the biological health of the soil. There are millions of microbes and microscopic creatures in a handful of soil, some good and some bad. The job of the gardener is to feed the beneficial ones and deter the harmful ones. The best way to do this is to add generous quantities of organic material to the soil in the form of home compost, commercial compost, mushroom compost or manure. These products will condition the soil to improve drainage, conserve water, allow for air movement and feed the plants, beneficial microbes and earth worms. Rebuilding your existing soil by adding organic material may be better than buying new soil. Adding composted mulch to the soil surface is also very beneficial.

If you need to purchase top soil look for a quality compost-based soil that has been heated to kill pathogens and weed seeds.

Search the GardenWise site for more information on organic fertilizer.