Unit 1 Learning Activities
Soil Texture Answers
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Unit 2 Learning Activities Unit 3 Learning Activities Unit 4 Learning Activities
Unit 1 Home 1.1.5.3 Soil Texture Answers
1.1.6 Analytical Problem Solving Procedure: An Approach 1.1.7 Soil Surface Area Solutions
1.1.9.9 Solution to Soil Physical Properties and Water Calculations 1.2.1.4 Surface Tension of Water
1.2.2 Capillarity 1.2.6 Soil Water Holding Concepts
1.2.6.1 The Sponge Model of Soil 1.2.6.2 Soil, Water, and Root Extraction
1.3.6 Brief Synopsis of Great Plains Irrigation 1.3.7 Is the grass greener?
1.4.3.6 Soil Temperature 1.5.1 Erosion Damages
1.5.1, 1.5.4 Erosion Impact Presentation 1.5.1, 1.5.2, 1.5.3 Erosion Mechanics Presentation
1.5.4.5 What's a plow anyway? 1.5.4.5 Soil Residue
Exam 1 Review Solution
Hydrometer Analysis: A sedimentation procedure was used to identify the soil separates. The corrected 40-second and 2-hour readings are given. (Temperature affects the density of water, so a temperature correction is necessary when using hydrometer analysis.)
Sample
Sample size, g 40-second reading, g/l 2-hour reading, g/l
One
 50
 28
 7
Two
 50
 32
 21
Three
 50
 48
 11
Four
 100
 12
 2
Determining the particle size distribution: The hydrometer measures the density of the solution (what remains in suspension), so the 40-second reading measures the amount of silt + clay in suspension, while the 2-hour reading measures the amount of clay in suspension. So, the clay can be determined directly, and the others by difference. The amount of sand is the difference between the sample size and the 40-second reading. The amount of silt is the difference between the 40-second and 2-hour readings. The solutions are given below the p. 15 problems.
1.1.5.3 Particle Size Distribution:
Sand, %
 Silt, %
 Clay, %
 Soil Texture Class
60
 25
 15
 sandy loam
35
 45
 20
 loam
25
 40
 35
 clay loam
50
 10
 40
 sandy clay
80
 15
 5
 loamy sand
20
 30
 50
 clay
5
 60
 35
 silty clay loam
Hydrometer Analysis Results
Sample
 Sand, % Silt, % Clay, % Soil Texture Class
One
 100*(50-28)/50= 44
 100*(28-7)/50= 42
 100*(7/50)= 14
 loam
Two
 100*(50-32)/50= 36
 100*(32-21)/50= 22
 100*(21)/50= 42
 clay
Three
 100*(50-48)/50=  4
 100*(48-11)/50= 74
 100*(11)/50= 22
 silt loam
Four
 100*(100-12)/100= 88
 100*(12-2)/100= 10
 100*(2)/100= 2
 sand