When you have a look at the tire of the car, you will notice that the numbers are written in the following pattern: P215/50R17. What is the Meaning of the First Letter? The first alphabet on the tire can be P, LT, ST or T. Sometimes there is the absence of the first alphabet. The first alphabet denotes:
Clay is one of the three principal types of soil, the other two being sand and loam. A certain amount of clay is a desirable constituent of soil, since it binds other kinds of particles together and makes the whole retentive of water. Excessively clayey soils, however, are exceedingly difficult to cultivate.
Soil color is mainly produced by the minerals present and by the organic matter content. Yellow or red soil indicates the presence of oxidized ferric iron oxides. Dark brown or black color in soil indicates that the soil has a high organic matter content. Wet soil will appear darker than dry soil. However, the presence of water also affects soil color by affecting the oxidation rate. Soil that has a high water content will have less air in the soil, specifically less oxygen.