Physical Properties of Soil

Soil Texture What is Soil Texture? It is the proportion of three sizes of soil particles. Which are: Sand (Large) Silt (Medium) Clay (Small)

Soil Texture What is Sand? It is the largest and is further divided into four subcategories. They are: Very coarse sand Coarse sand Medium sand Fine Sand

Soil Texture Sand it is the largest soil separate and is composed mainly of weathered grains of quartz. Sand is also gritty to the touch. Sand grains will not stick to each other.

Soil Texture Sand What will sand do to the soil? It will improve the soil by improving the water infiltration and aeration

Soil Texture Silt is the medium sized soil separated. Silt particles are silky or powdery to the touch Silt grains will not stick to one another just like sand grains. Silt is the best soil as it has the ability to hold large amounts of water in a form plants can use.

Soil Texture Clay is the smallest size soil separate. It is composed of tiny crystals Clay is formed by chemical reactions between weathered minerals to form tiny particle of new minerals. Clay will hold more plant nutrients than any other separate. Clay grains will stick to one another.

Soil Texture There are 12 textural classes which can be seen in the next slide.

Soil Texture Pass out picture of triangle and lets see if we can classify some soils.

Soil Texture 1. 40% sand 22% clay and 38% silt What is the soil classified as?

Soil Texture 2. 90% sand 10 % clay and 25 % silt What is it?

Soil Texture 3. 30% sand 50 % clay and 15% silt What is it?

Soil Texture 4. 10 % sand 80% clay and 10% silt. What is it?

Soil Texture Lets go and texture some of the kits that we have. See if you can make a ribbon and with which one? Which one feels grittiest? Which one feel powdery?

Soil Density and Permeability What is Particle Density? it is the density of solid particles only.

Soil Density and Permeability What is Bulk Density? It is the mass of a volume of undisturbed oven dry soil BD= Weight dry soil ___________= __G__ Volume dry soil cm3

Soil Density and Permeability Example BD: The core is 500 cubic cm that weighs 650 grams What is the answer?

Soil Density and Permeability Answer: BD= 650g ______ = 1.3 g/cm3 500 cm3

Soil Density and Permeability Soil Porosity Total pore space is measured of the soil volume that holds air and water. SP=wet weight(g) – dry weight (g) _____________________ x100 soil volume (cm3)

Soil Density and Permeability Example: The soil core before had a volume of 500 cubic centimeters and weighed 650 grams when dry. When wet the same core weighed 900 grams. Calculate Porosity.

Soil Density and Permeability Answer: 900-650 _________x100 =50% 500

Soil Density and Permeability What is Permeability? is the ease of which air, water, and roots move through the soil

Soil Density and Permeability What is Hydraulic Conductivity? Is the measure of the rate of water movement through the soil

Worm Castings http://www.youtube.com/watch?v=44AvH-fPxp0

Horizons

Horizons O - Organic matter A- topsoil B-Subsoil C- Parent material Bedrock

Soil Acid Ph- is a measure of the degree of acidity or alkalinity Acid – is sometimes referred to as sourness Alkalinity is referred to as sweetness

Soil Acid

Soil Acid Liming- will increase the pH in soil Gypsum-Will decrease the pH in soil. Sulfur and Aluminum sulfate will also decrease soil pH.

Nurtrients Macro-nutrients N-nitrogen P2O4-Phosphorus K2O – Potassium Ca-Calcium Mg-Magnesium S-Sulfur

Nutrients Micro-Nutrients Iron Manganese Boron Zinc Copper Molybdenum chlorine