Which description lists the components of ideal, healthy soil?

• A. 50% pore space, 45% mineral component, roughly equal ratios of water and air
• B. 30% pore space, 60% mineral, 10% water
• C. 60% pore space, 30% mineral, 10% water
• D. 40% pore space, 40% mineral, 20% water

Answer: (A)

Soil works best when there is a balance between the solid mineral matter and the pore spaces that hold water and air. In healthy soil, about half the volume is pore space, and the solid portion is mainly mineral material with a small amount of organic matter. Within that pore space, water and air are present in roughly equal portions, which supports root growth, drainage, and microbial activity.

The description that uses 50% pore space, 45% mineral, and roughly equal water and air fits this pattern. It implies a small amount of organic matter (about 5%), with water and air each making up roughly half of the pore space, so overall the soil has good drainage and aeration plus a solid framework for roots and biology.

Other options misstate this balance: they either give too little or too much pore space, or separate water in a way that doesn’t align with the pore space, leading to an unrealistic or unstable soil structure.