Soil conditions are of critical importance to plants. To achieve a perfect union between plants and soil, it is therefore important to both understand soil characteristics, and the specific preferences of individual plants.
Soils can be defined by texture, pH and fertility:
A. Soil texture is the composition of the soil. Soils are a blend of mineral particles and organic matter, which is essentially decomposed plant material. A great deal of soil structure is related to the size of the mineral particles. Large particles are basically sand, medium sized particles are called silt, and extremely small (microscopic) particles are the major constituents of clay.
- Sandy soils are typically very well drained, but because of this, they do not retain water well and are therefore subject to frequent periods of drought in dry climates.
- Clays, on the other hand, hold water very well, almost too well, such that they often drain poorly, and can drown the roots of plants, which require some degree of oxygen for aeration.
- The best soils are a mix of the various soil types along with a good amount of organic matter. In general, organic matter such as peat moss is the best way to amend poor soils, both those that are too sandy and those that are too heavy (clay).
B. Soil pH is the relative acidity or alkalinity of the soil. Soils with different pH levels are able to hold or provide various nutrients to plants in different ways. This is of particular importance in that specific plants have adapted to specific soil types, and may not perform in other types. In general, a neutral soil is best for most plants, meaning a pH of 6 to 7.5. It is possible to amend the pH of a soil, but this requires effort and much planning; specially prepared beds with custom-mixed soils are the best way to create growing environments for plants with specific pH preferences.
C. Soil fertility is a measure of the key nutrients available to plants from the soil. The major nutrients are nitrogen, which aids in the development of lush, green foliage; potassium, which is important in the development of fruits and increases resistance to disease; and, phosphorus, which aids in flower and root development, along with trace elements such as calcium, magnesium, copper and zinc. Plants will generally decline in soils which have nutrient deficiencies.
- Nutrients can be added to soils through applications of fertilizers. Fertilizers are rated by a universal system according to the composition of the three major nutrients. The first is the volume percentage concentration of nitrogen, the second is the concentration of phosphorus, and the third is the concentration of potassium. A 10-30-10 fertilizer has 10% nitrogen, 30% phosphorus and 10% potassium by volume, meaning that it would be effective in promoting the development of roots and flowers. In addition, fertilizers can include soil pH amendments which can help maintain the acidity of soils for certain acid-loving plants.
- Cultivation, earthworms, frost action and rodents mix the soil. This activity decreases the size of the peds to form a granular (or crumb) structure. This structure allows for good porosity and easy movement of air and water. The combination of ease in tillage, good moisture and air-handling capabilities, good structure for planting and germination are definitive of good tilth.
Source: www.northscaping.com
