Soil composition

Soil is a mixture of minerals, organic matter, water and air as shown below (FAO).

Soil physical properties

Soil physical properties include color, texture, structure, porosity, bulk density, consistence, aggregate stability, water content, water potential and temperature. These properties affect processes such as infiltration, erosion, nutrient cycling, and biologic activity.

Soil chemical properties

Soil chemical properties include concentrations of specific chemicals (e.g., C, N, S, P, Na, K, Ca, Mg, trace metals and elements), pH, cation exchange capacity, base saturation, salinity, sodium adsorption ratio, and electrical conductivity. These properties affect processes such as nutrient cycling, biologic activity, soil formation, pollutant fate, and erosion.

Soil biological properties

Soil biological properties include soil biota (bacterial and fungal abundance and diversity) and biological processes, such as respiration, nutrient cycling, mineralization, and organic matter cycling.