Final answer:
Soil is composed of approximately 40-45% inorganic mineral matter, 5% organic matter, and 50% air and water. The correct soil composition is closest to 40% inorganic minerals, 5% organic matter, and 50% air and water, plus living organisms. Soil quality is affected by compaction, which can reduce the air and water content, negatively impacting soil productivity.
Step-by-step explanation:
The composition of soil typically consists of a few key components in varying percentages. These components include inorganic mineral matter, organic matter, water, and air. Approximately 40 to 45 percent of the soil volume is made up of inorganic mineral matter, which is derived from the breakdown of rocks into smaller particles such as sand, silt, and clay. Organic matter comprises about 5 percent of the soil volume, including humus, which is composed of decomposing plant and animal material. This organic component is crucial for soil structure and fertility. Water and air together make up around 50 percent of the soil volume, with ideal conditions including equal parts of these two, filling the soil's pore space.
Given these percentages, the correct composition of soil would be closest to option b) 40% inorganic mineral matter, 5% organic matter, and 50% air and water, plus living organisms. Soil is indeed a heterogeneous mixture, with its quality dependent upon the correct balance of its components to ensure a healthy environment for plant life and microorganisms.
Soil compaction, due to heavy machinery or foot traffic, can adversely affect this balance by reducing pore space which, in turn, decreases the amounts of air and water the soil can hold. This compacted soil can become less productive due to the lack of adequate air and water needed by plants and soil microorganisms.