Short answers, pulled from the story.
A single gram of soil contains more living organisms than there are people on the entire planet. This composition includes bacteria, fungi, protozoa, and tiny animals that function as the planet's primary digestive system. The soil is a complex three-state system of solids, liquids, and gases that supports the life of plants and soil organisms.
Soil formation is governed by five interrelated factors often remembered by the acronym CROPT. These factors are climate, relief, organisms, parent material, and time. When reordered to climate, relief, organisms, parent material, and time, they form the acronym CROPT, highlighting the dynamic interplay between environmental conditions and geological history.
Mature soil profiles typically include three basic master horizons labeled A, B, and C. The solum normally includes the A and B horizons, while the living component of the soil is largely confined to the solum. These horizons differ in properties such as texture, structure, density, porosity, consistency, temperature, color, and reactivity.
Cation exchange capacity is the amount of exchangeable cations per unit weight of dry soil and is expressed in terms of milliequivalents of positively charged ions per 100 grams of soil. Negatively charged sites on colloids attract and release cations, which resist being washed downward by water and are at first out of reach of plant roots. This process preserves the soil fertility in areas of moderate rainfall and low temperatures.
A typical soil has a biomass composition of 70% microorganisms, 22% macrofauna, and 8% roots. The living component of an acre of soil may include 900 pounds of earthworms, 2400 pounds of fungi, 1500 pounds of bacteria, 133 pounds of protozoa, and 890 pounds of arthropods and algae. This biological community processes all organic matter as in a digestive system.
Historically, one of the best examples of large-scale soil erosion due to unsuitable land-use practices is wind erosion, the so-called dust bowl. This event ruined American and Canadian prairies during the 1930s. Immigrant farmers, encouraged by the federal government of both countries, settled and converted the original shortgrass prairie to agricultural crops and cattle ranching.