Components, rocks, soil particle size

In general, soil is an unconsolidated combination of inorganic and organic materials. The inorganic components of soil are principally the products of rocks and minerals that have been gradually broken down by weather, chemical action, and other natural processes. Soil particles, also known as soil separates, are divided into three main size groups sand, silt, and clay minerals [14]. 

The components of soils and rocks have different size, shape, and quality. The particle size of organic components usually is in the colloid range (<500 nm) mineral components have different dispersity. The first classification system of soils on the basis of particle size was done by Atterberg (1905). Practically, this classification has been used until now, though some countries have their own classifications, considering their widespread soil types. The size of soil particles will also determine how the soil fraction is named (e.g., clay, sand, silt, rock, etc.). Table 1.6 provides these names along with the standard diameter of the particles for the international classification system. 

The nature of the parent material is the most important factor influencing the mineral components of a soil. In particular, the textural (particle size) properties and inherent fertility are directly affected by the types of rocks and minerals found in the parent material. 

Fertile topsoil is a mixture of at least four components—mineral particles, water, air, and organic matter. The mineral particles are the particles of sand, silt, and clay. Many of the nutrients plants need are released as these particles are formed from the erosion of rock. The size of the particles greatly affects soil fertility. Large particles result in porous soil that has many pockets of space that collect water and air—up to 25 percent of the volume of fertile topsoil consists... 

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