Soil pH level
Soil organic matter and soil carbon sequestration
Permeability and porosity
Water holding capacity
Soils vary in their suitability for specific purposes. For example, in Queensland a deep, fertile clay soil is suitable for intensive agriculture but a shallow, sandy soil is better suited to grazing and growing native trees.
The suitability of a soil for a particular purpose can often be determined by looking at some of the easily recognisable features and carrying out simple tests. The most common properties used to compare and recognise soil are:
soil depth texture structure colour soil pH level nutrient status.
Other important soil properties include dispersibility, organic matter and soil carbon sequestration, permeability and porosity, salinity and water holding capacity.
An important feature of a soil is that it changes with depth. To properly analyse a soil, it should be examined from the surface to the parent material.
Soil texture (e.g. loam, sandy loam or clay) refers to the proportion of sand, silt and clay sized particles that make up the mineral fraction of the soil. For example, light soil refers to a soil high in sand relative to clay, and heavy soils are made up largely of clay.
Texture is important because it influences the amount of water that the soil can hold, the rate of water movement through the soil as well as its workability and fertility. For example, sand is well aerated but does not hold much water and is low in nutrients. Clay soils generally hold more water, and are better at supplying nutrients.
Texture often changes with depth so that roots have to cope with different conditions as they penetrate the soil. A soil can be classified according to the manner in which the texture changes with depth. The three profile types are:
uniform—same texture throughout the profile