Soil Texture and Structure
In the hydrometer experiment, which soil separate remained in suspension at the end of class?
Clay
Which has a higher buffering capacity: soil or water?
Soil
Which soil would you expect to have higher plant available water: sandy loam or silt loam?
Silt loam
Which soil has a higher CEC: sandy loam or silty clay?
Silty clay
What is the percent potassium in a 30-15-20 fertilizer?
20%
Soil _______ describes the relative proportions of sand, silt, and clay.
Texture
Which has a higher concentration of H+: a soil with a pH of 6 or a soil with a pH of 8?
The soil with the pH of 6
Does soil water potential increase or decrease as soil gets drier?
Decreases (gets more negative)
Which has a higher CEC: a loam with 2% organic matter or a loam with 8% organic matter?
The loam with 8% organic matter
Did the La Motte soil nutrient test give us precise or approximate nutrient concentrations?
Approximate
When completing the soil texture by feel and your soil sample makes a long, strong 5 cm ribbon, then the soil texture class may be a: silt loam or silty clay?
Silty clay
Name some information that is included in a soil survey.
Texture, drainage class, parent material, description of a typical profile...
Plant available water is held between ______ and ______.
Field capacity, wilting point
In lab 7, we combined soil and methylene blue dye. After filtration, the color of the dye was much lighter. Why? What happened to it?
The positively charged dye became adsorbed to the negatively charged soil
Name two purposes of soil nutrient testing.
- To determine the plant-available concentrations of soil nutrients.
- To avoid overapplying fertilizer, which is a waste of money and harmful to the environment.
- To maximize plant productivity.
Explain a scenario where the texture by feel method would be more appropriate to use than the hydrometer method to estimate soil texture.
When you are in the field and do not have access to lab equipment
Name the level of soil taxonomy we were looking at when we looked at Web Soil Survey.
Soil series
How did we convert from gravimetric moisture content to volumetric moisture content in lab?
We multiplied gravimetric moisture by the soil bulk density to obtain volumetric moisture.
Define soil cation exchange capacity to someone who has never taken a Soils class before.
The total negative charge of the soil; how many positively charged ions the soil can retain.
What did the soil respirometer measure? What is the purpose of taking this measurement?
Carbon dioxide concentrations, which reflects microbial activity
What do hydrometers measure?
The specific gravity of solutions
Why does limestone neutralize soil acidity?
Limestone contains a conjugate base (CO32-), which neutralizes acidity (H+).
Where is water found in soil at its wilting point?
Tightly adsorbed to the soil particles in a thin film
Name two benefits that a soil with a high cation exchange capacity provides the soil.
-Retention of nutrients
-Retention of water
-High buffering capacity
-Filtration of contaminants
When conducting the earthworm counts, which two ecological groups were most commonly spotted?
Epigeic and endogeic