University:
Sam Houston State University
Course:
GEOL 1405 | Geologic & Environmental Hazards
Academic year:

2022
Views:

326

Pages:

10
Author:

Clint W.

Soil • Soil contains four main components: inorganic material, organic matter, water, and air. Soil • Ideal soil should contain about 50% solid material and 50% pore space. • About half of the pore space should contain water and half of the space should contain air. Soil • Inorganic material consists of rock slowly broken down into small particles. • The organic material is made up of dead plants and animals varying in stages of decay. Soil • The percentages of the four main soil components varies depending on the kind of vegetation, amount of mechanical compaction, and the amount of soil water present. Soil • Soil is formed very slowly. • It results from natural forces acting on the mineral and rock portions of the earth’s surface. • The rock is slowly broken down to small particles resulting in soil. Organic Matter • In most soils, the proportion of organic matter is relatively small (2-5%). • Its importance in formation and production is much higher than the small % would suggest. Organic Matter • Soil organic matter decaying plant and animals. • As they die, they are attacked by microorganisms: fungi, bacteria, and others. Organic Matter • There are two types of organic matter. • Original tissue is that portion of the organic matter that can still be recognized. • Twigs and leaves covering a forest floor are good examples. Organic Matter • Humus is organic matter that is decomposed to the point where it is unrecognizable. • The brown color you sometimes see in soil is a good example. Organic Matter • Purposes of organic matter: affects the soil structure by serving as a cementing agent, returns plant nutrients to soil (P, S, N), helps store soil moisture, makes soil more tillable for farming, provides food (energy) for soil microorganisms, which makes the