Soil Components

Melissa Morris

Four Major Components Organic Matter Water Air Mineral Materials Exist in a close mixed condition Interactions among components yields

variation in environment for plant growth

Organic Matter An accumulation of plant and animal

deposits Constantly being decomposed Small percentage of soil – 2-6% by weight Largely responsible for manageable

characteristic of productive soil Source of soil nitrogen, sulfur and

phosphorus Main source of energy for soil organisms

Water

Is held in pore spaces between soil particles

Soil water with its salts make up the soil solution

Supplies nutrients to growing plants

Air Located in soil pores between soil particles

These pores are the passageways for oxygen movement

Aeration can be limited by water and compaction

Mineral Materials

Variable in size and composition Remnants of parent material 4 sizes of Inorganic (mineral) particles

Gravel-very coarse Sands-coarse Silt-fine Clay-very fine

Gravel

Silt

Sand

Clay

Images found at: www.mo.nrcs.usda.gov

Soil Structure Particles group into aggregates CLAY helps bind

Too much clay will form a barrier to drainage SAND aids drainage and aeration

Too much sand causes water to drain too fast and makes soil dry out

Different proportions of each will form different soil textures

Ideal soil composition Ideal soil is not too sandy or too much clay Excessive tillage destroys structure 45% sand, silt and clay mixture Pore spaces - 25% air and 25% water 5% organic matter

Image found at: www.ext.colostate.edu

Soil Categorization

Categorized by finding % of each sand, silt, and clay

Use soil triangle to find name % must add up to 100

==================================== Find the name of a soil that is 25% sand,

45% silt, and 30% clay using the soil triangle.