Final answer:
Soil is indeed about 50% air and water, with the rest consisting of mineral and organic matter. This composition is crucial for healthy soil that can support plant life and facilitate vital biological processes.
Step-by-step explanation:
The statement that soil is approximately 50% air plus water is true. In an ideal soil composition, there should be about 50 percent solid material and 50 percent pore space, with half of this pore space containing water and the other half containing air. The solid component includes inorganic mineral matter, which comprises about 40 to 45 percent of the soil volume, and organic matter, which accounts for roughly 5 percent of the soil volume.
These components are essential for soil health and its ability to support plant life, as the organic matters such as humus improve the soil structure and provide necessary nutrients and moisture, while the inorganic materials contribute to the soil's texture and fertility. Additionally, the air in the soil allows for the respiration of plant roots and soil microorganisms, which are vital for nutrient cycling and maintaining soil structure.