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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 sandCoarse sandMedium sandFine 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
SandWhat 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 touchSilt 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 crystalsClay 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 gramsWhat is the answer?
Soil Density and Permeability
Answer:
BD= 650g______ = 1.3 g/cm3500 cm3
Soil Density and Permeability
Soil PorosityTotal 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- topsoilB-SubsoilC- Parent materialBedrock
Soil Acid
Ph- is a measure of the degree of acidity or alkalinityAcid – is sometimes referred to as sournessAlkalinity is referred to as sweetness
Soil Acid
Soil Acid
Liming- will increase the pH in soilGypsum-Will decrease the pH in soil.Sulfur and Aluminum sulfate will also decrease soil pH.
Nurtrients
Macro-nutrientsN-nitrogenP2O4-Phosphorus
K2O – Potassium
Ca-CalciumMg-MagnesiumS-Sulfur
Nutrients
Micro-NutrientsIronManganeseBoron ZincCopperMolybdenumchlorine