Soil quality is determined by its physical, biological, and chemical properties. This video focuses on physical properties, including soil organic matter, structure, water holding capacity, infiltration, and compaction. Healthy and fertile soil is essential for plants, people, and the planet.

Soil organic matter (SOM) is fundamental for healthy and productive soil. It comprises living, dead, and very dead components. Though typically 1-6% of topsoil, a 1% increase in SOM can boost crop yields by 12%. SOM enhances biological activity, improves soil structure, increases water infiltration and storage, aids decomposition, and releases nutrients. It acts like a sponge, retaining water and nutrients, and nourishes beneficial soil organisms that improve structure and fight plant diseases.

While soil texture (sand, silt, clay) is inherent, soil structure—how particles fit together—can be changed. Ideal loamy soil is 50% soil and 50% air/water spaces. Good 'crumb structure,' known as aggregates by soil scientists, ensures sufficient pores. Aggregates are bound by chemical bonds from organic matter and clay, sticky substances from bacteria and root hairs, and wrapping by fungi and root hairs. Water-stable aggregates indicate a soil's ability to maintain structure under extreme conditions like heavy rain.

Soils that crust after heavy rain prevent water infiltration, leading to runoff that washes away precious topsoil. Cover crops, compost, and perennial cover feed soil organisms, which in turn help bind soil aggregates and maintain soil structure, preventing crusting and improving infiltration.

Healthy roots require both air and water. Rain needs to infiltrate the soil into the root zone and also drain so roots aren't waterlogged. Infiltration rate, a crucial soil property, determines how much rainfall enters the soil versus running off. Runoff wastes water, nutrients, and topsoil, polluting streams. Infiltration is influenced by pore size between aggregates, soil texture, and channels from roots, insects, and earthworms.

Compaction, caused by tractor tires or foot traffic, especially when soil is wet, compresses pores and reduces infiltration. Compacted soil leads to runoff and crusting. Roots struggle to penetrate compacted layers deep in the soil. A soil penetrometer measures compaction; if pressure exceeds 300 lbs per square inch, roots cannot penetrate. Solutions include ripping compacted layers or planting deep-rooting cover crops to break up hardpans.