In addition to nematode activity, the bacteria and fungi present in the soil decompose all sorts of organic material, such as leaves, dead roots, and animal carcasses. Living organisms and their organs, such as roots, produce carbon dioxide, which combines…
The climate is a globally varying feature and weighs heavily upon the weathering of rocks for soil parent material. For example, in desert or arid regions, there is little rain weathering and the soils are poorly developed. In contrast, areas…
The development of soils can be significantly affected by vegetation, animal inhabitants, and human populations. Any array of contiguous soils influenced by local flora and fauna is termed a biosequence. To return to the climosequence along the Cascade and Sierra Nevada ranges discussed above, the vegetation observed…
The term climate in pedology refers to the characteristics of weather as they evolve over time scales longer than those necessary for soil properties to develop. These characteristics include precipitation, temperature, and storm patterns—both their averages and their variation. Climate influences soil formation primarily through effects of water and solar…
Topography, when considered as a soil-forming factor, includes the following: the geologic structural characteristics of elevation above mean sea level, aspect (the compass orientation of a landform), slope configuration (i.e., either convex or concave), and relative position on a slope (that…
As a quick review, soil development is first predicated on the formation of the parent material. Parent material accumulates via the weathering of igneous, sedimentary, and metamorphic rocks. Igneous rocks are ones from volcanic activity, sedimentary rocks are formed from…
In looking closer at soils, it is important to understand that there are general regions or horizons of soil development that are usually obvious in an undisturbed area. For example, if we found an undisturbed area, and dug down 3 to 6…
Where a plant grows and what resources are available to it is of vital importance to the life of a plant. The soil type and quality can be the difference between survival and termination of a plant. Soil is a…
It is important to note that root nodules are not root knots, which are root swellings in response to worm invasions. Root nodules are beneficial bacterial colonies that are visible as small swellings in the root system. The bacteria aid the…
Mycorrhizae are fungal roots found in many plants. These fungal associations are important for both the plant and for the fungal and are therefore considered to be mutualistic. Essentially, the fungus will have a greater capacity for absorbing phosphorus than…