C. Physical properties 1. Soils are classified into textural classes using the soil texture triangle. Soil structure -soil particles form aggregates, which occur due to exudates from plants and microorganisms that bind individual particles together into various sized aggregates. This affects the ability of soils to hold water and oxygen. Soil water - includes both the amount of water contained by a soil and how available that water is to plants.
Cohesion is the process of water molecules being joined together in chains.
Both these forces hold water to soil particles and make them less available to plants. As soils dry these forces hold much if not all the soil water. The force exerted by molecules moving through the membrane is called the osmotic pressure. Soil water potential - refers to the energy status of the soil water, so as water potential increases the amount of energy needed by plants to get water decreases. The higher the water potential the higher the water concentration in the soil.