The water holding capacity of a soil is a very important agronomic characteristic. Soils that hold generous amounts of water are less subject to leaching losses of nutrients or soil applied pesticides. After a soil is saturated with water, all of the excess water and some of the nutrients and pesticides that are in the soil solution are leached downward in the soil profile. Soil water holding capacity is controlled primarily by the soil texture and the soil organic matter content.
Soil texture is a reflection of the particle size distribution of a soil.
In general, the higher the percentage of silt and clay sized particles, the higher the water holding capacity. This large surface area allows the soil to hold a greater quantity of water. The amount of organic material in a soil also influences the water holding capacity. As the level of organic matter increases in a soil, the water holding capacity also increases, due to the affinity of organic matter for water. In the past 100 years, many laboratory methods have been developed around the world to determine soil water holding capacity.