Soil Texture Flashcards
What is texture?
Texture is used to describe the feel of a substance, based upon the smoothness or roughness of its surface
What is soil texture?
Soil texture is a measure of the sizes of grains within a soil
What gives soil its texture?
The relative percentages of sand, silt and clay
What is soil texture determined by?
The size ans proportions or ratios of the small individual mineral particles
What size is sand?
2 to 0.06mm
What size is silt?
0.06 to 0.002 mm
What size is clay?
Less than 0.002 mm
Characteristics of sand
Feels gritty, particles are rounded or angular, inert
Characteristics of silt
Feels slippery, very small, darker in colour
Characteristics of clay
Feels sticky, flat plate like particles, surface negative charge allows cation exchange
What is a loam?
Loam is a mixture of sand, silt and clay
How do you measure soil textural class in the field?
Finger analysis
How do you measure soil textural class in the lab?
Sieving and separating the proportions of each particle. Soil hydrometer
Basic analysis of sand
Squash but not roll, if loamy it will stain hands
Basic analysis of silt
Smears, smooth and silky, eggshell finish not gloss
Basic analysis of clay
Smears, smooth and polishes, sausage test
What is the difference between soil structure and soil texture?
Texture is a permanent property whereas soil structure can be changed
Why is soil texture important?
Indicates soil properties or field characteristics, indicates which plant species will grow best and affects the rate of chemical application such as lime
What are the field characteristics of soil?
Drainage, water retention , aeration, temperature changes, ease of cultivation, stability, fertility and susceptibility to compaction
What other factors affect soil texture?
Stones, lime(feels more sticky) and humus (feels more sticky)
