Become a Green Thumb Pro 2026 – Ace the Master Gardener Test and Blossom!

Soil’s physical makeup is defined by four distinct components: mineral matter, air, water, and organic matter. Mineral matter is the solid particles derived from weathered rock and gives soil its bulk and mineral nutrients. Air and water occupy the open pore spaces between particles; together they determine drainage, aeration, and the availability of oxygen to roots and soil organisms. Organic matter consists of decomposed plant and animal material (humus) that improves structure, water retention, and nutrient holding.

Other options mix factors that are not physical components. For example, temperature, moisture, nutrients, and pH are properties or conditions of soil, not the four physical components themselves. Microbes and roots are living organisms, not basic physical components. Sand, silt, and clay describe texture within the mineral portion rather than separate components.