Back to Basics . . . Part 10 Soils ... You don’t have to “live with them” We all have to modify our soil in some way to improve it for the types of plants we want to grow. It is rare to be blessed with a natural soil that does not need some type of soil conditioner. In this chapter we will look at soils in general and what types of materials we can use to make them better. As we know there is a great variety of different types of soil. Generally soils types are designated by particle size and fall into one of three major classifications. Clay . . . A clay soil, also referred to as a heavy soil is one that is composed of very small particles. Since the particles can pack together tightly they tend to have poor aeration and poor drainage. This gives them a high moisture holding capacity sometimes to the detriment of plants. They tend to compact easily. The spaces between the soil particles are small allowing the moisture to be held for long periods of time sometimes resulting in poor drainage particularly after moderate to heavy rains, the air spaces in the soil fill up with water, thereby excluding the air and causing the plant roots to “drown” from too much water and/or “suffocate” from lack of air. By thoroughly incorporating organic matter like manures, compost and peat moss and inorganic materials like perlite and vermiculite into clay soils we can make the soils lighter and improve the drainage and aeration, resulting in healthier root systems. Sand . . . Sandy soils are composed of relatively large soil particles which allow plenty of air space (sometimes too much, resulting in too rapid a water loss). The particles tend not to pack together, drainage is generally good. The main problem with sandy soils is that generally the “water holding capacity” is too low. Water (and nutrients) drain through too fast and consequently the soil dries out too fast. The addition of manures, compost and particularly peat moss will increase the water holding capacity of sandy soils. Remember also that the dissolved nutrients will be held longer resulting in more complete absorption by the plants. Loam . . . Loam is a soil that is composed of a mixture of sand, silt and clay. It allows good drainage and aeration while having sufficient water holding capacity. What is the ideal soil ? The ideal soil mix would be one that has approximately 50% solid and 50% air space and under ideal conditions the air space would be 50% air and 50% water. A good loam high in organic matter would fit this requirement. Please keep in mind what we’ve been talking about so far are soils that are classified according to particle size. The soils can be derived from organic sources which are already high in organic matter or from mineral sources. Organic soils will already have a high moisture holding capacity while mineral soils will not. Mineral soils are derived primarily from rock and stone that have been weathered over hundreds of years to form a “soil”. These will need generous amounts of organic materials added to be improved. Most soils of course will not be one or the other but a combination of both.
Posted on: Sun, 06 Oct 2013 01:44:00 +0000
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