4.3 APES

Soil Composition

Soil is composed of three main particle types: sand, silt, and clay.

Soil Texture

Defined by the percentage of sand, silt, and clay, always summing to 100%; for example, 40% sand, 40% silt, and 20% clay is classified as loam.

Porosity

Refers to the amount of pore space in the soil, with sandy soils having higher porosity and clay having lower porosity.

Permeability

Indicates how easily water drains through soil; higher porosity correlates with higher permeability.

Water Holding Capacity

Refers to soil's ability to retain water; more porous soils typically have lower water holding capacity.

Loam

Considered ideal for plant growth due to its balanced texture of sand, silt, and clay.

Nutrient Composition

Key nutrients for soil fertility include nitrogen (N), phosphorus (P), potassium (K+), magnesium (Mg2+), calcium (Ca+), and sodium (Na+).

Organic Matter

Plays a critical role in nutrient release and retention, enhancing soil fertility.

Soil Fertility

Defined as the ability of soil to support plant growth, influenced by nutrient availability and management.

Acid Leaching

A process that can decrease soil nutrients by removing them through acidic rain or soil conditions.

Nutrient Cycling

The recycling of nutrients back into the soil facilitated by decomposer activity.

Soil Quality Testing Methods

Techniques to assess soil properties, including texture, permeability, pH, color, and nutrient levels.

Topsoil Erosion

The removal of topsoil that can significantly reduce nutrient levels, impacting soil fertility.

Compacted Soil

Soil that has been compressed, reducing its water holding capacity, often caused by machinery or livestock.

Soil Texture Chart

A tool used to determine the composition of soil based on percentages of sand, silt, and clay.