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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.