SOIL: Make it Work for You! We Study Soil Because It’s A(n) Great integrator: all parts of ecosystem Producer and absorber of gases Medium for plant growth Medium of crop production Home to organisms (plants, animals and others) Waste decomposer Snapshot of geologic, climatic, biological, and human history Source material for construction, medicine, art, etc. Filter of water and wastes Essential natural resource
SOIL: Make it Work for You! Soil Forming Factors Parent Material Topography (The first four factors over) Time Climate Biota These five factors work together to create a unique soil profile made of layers called horizons.
The way the soil “feels” is called the soil texture.
Soil texture depends on the amount of each size of mineral particles in the soil.
Sand, silt, and clay are names that describe the size of individual mineral particles in the soil.
Sand are the largest particles and they fell “gritty”
Silt are medium sized, and they feel soft, silky or “floury”
Clay are the smallest sized particles, and they feel “sticky”
SOIL: Make it Work for You! Soil Texture: Relative Size Comparison of Soil Particles frisbee Silt (feels floury) dime Clay (feels sticky) (0.05 - 0.002 mm, USDA) (0.02 - 0.002 mm, ISSS) (< 0.002 mm, USDA) (< 0.002 mm, ISSS) beachball Sand (feels gritty) (2.00 - 0.05 mm, USDA) (2.00 - 0.02 mm, ISSS)
SOIL: Make it Work for You! Triangle Key: S = sand or sandy Si = silt or silty C = clay L = loam or loamy Soil Texture Triangle SiCL % Sand % Silt % Clay S LS SL L SiL Si CL SiC C SC SCL 0 100 100 100 0 0
SOIL: Make it Work for You! Soil Structure: with Structure Granular Blocky Prismatic Columnar Platy
SOIL: Make it Work for You! Single Grained Massive Soil Structure: without Structure
SOIL: Make it Work for You! Bulk Density: a measure of soil compaction To calculate Bulk Density: 1 cm. (so, there is 1 cubic centimeter of soil) Sample is made of Solids and Pore Spaces 1.33 gms. Volume = 1 cm 3 Weight = 1.33 gms Bulk Density = 1.33 1 Bulk Density = 1.33 gms / cm 3 Bulk Density = Weight of Soil Volume of Soil
SOIL: Make it Work for You! Bulk Density & Compaction Zones 8 inches 1.43 0 inches 7 inches 9 inches 10 inches Depth Bulk Density (grams / cm 3 1.90 1.87 1.84 1.80 1.60 Plow Layer Compacted Zone Uncompacted subsoil
SOIL: Make it Work for You! Basic Soil Components Soil Particles: Mineral and Organic Pore Spaces: location of air and water
Field Capacity : water that remains in soil beyond the effects of gravity.
Permanent Wilting Percentage : amount of water after the permanent wilting point is reached.
Available Water : amount of water in the soil between the field capacity and the permanent wilting percentage.
SOIL: Make it Work for You!
SOIL: Make it Work for You! Relationship between soil texture and water availability Sand Sandy Loam Silt Loam Clay Loam Clay Inches of Water Per ft. of Soil 1 2 3 4 Permanent Wilting Percentage Field Capacity Available Water
SOIL: Make it Work for You! At Saturation At “Available Water Soil at Different Moisture Levels: Pore Space Water on soil particle surface Pore Spaces are filled with water
SOIL: Make it Work for You! Soil at Different Moisture Levels: At Permanent Wilt Compacted No water remains attached to soil particles Pore spaces are collapsed
Compacted Zone Impermeable Layer SOIL: Make it Work for You! H 2 O H 2 O Non-Compacted Compacted
Sand Over Clay Impermeable Layer SOIL: Make it Work for You! H 2 O H 2 O
SOIL: Make it Work for You! Perched Water Table Clay Over Sand H 2 O H 2 O
Possible pH Ranges Under Natural Soil Conditions black walnut: 6.0-8.0 Most desirable carrot: 5.5-7.0 cucumber: 5.5-7.0 spinach: 6.0-7.5 tomato: 5.5-7.5 white pine: 4.5-6.0 Very strong Strong Moderate Slight Slight Moderate Strong Very strong Neutral Acid Basic 3 4 5 6 7 8 9 10 11 1 2 12 13 14 Most agricultural soils Extreme pH range for most mineral soils cranberry:4.2-5.0 apple: 5.0-6.5
SOIL: Make it Work for You! - - - - - - - - - - - - - - - Al +3 - - - K + Clay Particle Soil reactions in neutral to high (alkaline) pH conditions Clay and organic particles have a negative charge - - - - Mg +2 H + Mg +2 K + H + Ca +2 Ca +2 PO 4 -3 NO 3 - NO 3 -
SOIL: Make it Work for You! Soil reactions in low (acid) pH conditions Clay and organic particles have a negative charge - - - - H + H + Al +3 K + H + Al +3 Al +3 PO 4 -3 - - - - - - - - - - - - - - - Al +3 - - - K + Clay Particle NO 3 - NO 3 -