APES Chapter 9 Study Guide

Soil formation is a very slow and complex process. First, there are parent material, such as bedrock, that is eroded and broken down in to smaller particles by weathering, which is the physical, biological, and chemical breakdown of rocks and minerals. Then, organic matter enters the soil, as well as gases produced by organisms in the soil. The decomposition of organic matter, also known as humus is an important as humus holds moisture and nutrients that are essential to plant life.

Someone would add clay to soil so that the soil would have to be less irrigated saving more water.

Porosity is the measure of space in between particles while permeability is the ability to flow between spaces.

Sand would have a high porosity because the larger particles will leave bigger spaces.

Sand would have the most permeability as well because the larger spaces in between the particles will allow liquids to flow through easier.

Scientists would test for the color to see how healthy the soil is, the texture to measure its porosity and permeability, and its structure to see how easily it clumps.

Scientists would test the pH, as plants can’t survive in too basic or acidic environment, the cation exchange capacity to see how much nutrients plants can absorb, and the amount of gases in the soil as plants take in gases from the soil.

Soils low in pH are less productive because the cation exchange capacity decreases and the ions the plants need leach away.

Erosion, desertification, salinization, waterlogging, nutrient depletion, structural breakdown, and pollution are seven ways soil is degraded.

The biggest cause of soil degradation is erosion.

Over cultivating fields, overgrazing rangelands, and deforestation are three ways humans make land vulnerable to erosion.

As soil degrades, plants are unable to grow in the areas with degraded soils. As a result, the degraded soil is more erodible by wind and water causing more degradation.

Crop Rotation, Contour Farming, Terracing, Intercropping, Shelterbelts, and Reduced Tillage are ways farmers can reduce wind and water erosion.

Crop rotation

Reduced tillage stops farmers from digging up soil and exposing it to wind and water.