What are Texture, Porosity, Loam, and Acidity in Fertile Soil?

Texture

• Fertile soils usually contain high amounts of organic matter, which affects soil texture. Texture refers to the amount of sand, silt or clay particles in the soil. According to the Kansas State University Department of Agronomy, many soil scientists consider soil texture to be its most important quality, since it plays a large role in water and nutrient availability. Soils that contain high amounts of clay and sand are usually classified as poor soils, since they cannot retain enough nutrients to sustain the growth of most plants.

Porosity

• Fertile soils are porous enough to allow water to penetrate the surface, but not so porous that they do not retain water. In other words, they have the perfect balance of permeability and retention. This quality significantly contributes to soil fertility, since it allows plant roots to receive adequate nutrients while also giving them room to breathe. Porosity is closely related to soil texture. In sandy soils, for example, the large particles are spaced far apart from each other, which can quickly result in drought conditions for plant roots. Fertile soils have ideal texture, which contributes to their porosity.

Loam

• The ideal texture that most fertile soils possess is often referred to as "loam." Loamy soils have a perfect balance of sand, clay and silt soil particles, containing all three in almost equal amounts. Loam soils have a medium texture that retains enough water to support plant life and also provides adequate oxygen to plant roots. You can test your soil to see if it is loamy with a simple exercise. Squeeze a ball of soil in your hand. If it stays in the shape of a ball without releasing water or becoming very sticky, it is probably a loamy soil.

Acidity

• Soil pH measures the acidity or alkalinity of a given soil. Acidic soils have a pH below 7, and alkaline soils have pH above 7. Most plants prefer pH levels between 5.8 and 7.0, according to the University of Minnesota Extension. Fertile soils usually have pH levels that fall within this range, due to the presence of organic matter. When soils become too acidic or too alkaline, nutrient availability is affected, which may result in deficiency or toxicity.