The ill effects of acidity in subsoils can be ameliorated by adding gypsum (CaSO4 2H2O) to the soil surface. Which of the following most likely helps account for this effect?
A) Sulfate ions from the gypsum react with H ions in the subsoil to form H2SO4.
B) Gypsum stimulates root growth in the surface soil horizons.
C) Gypsum dissolves and leaches downward, increasing the Ca/Al ratio in the soil solution in subsoil layers.
D) Calcium from the gypsum replaces hydrogen from colloids in the subsoil thereby increasing the soil pH.
E) The gypsum replaces hydrogen from colloids which moves down the profile and decreases the pH of the subsoil layers.
Question 2Which of the following would occur when lime is added to the surface of a soil at pH 6.0?
A) Earthworms would help move the limestone down into the soil profile.
B) The release of H+ ions from the exchange complex would help reduce the soil pH.
C) CO2 from root and microbial respiration would quickly solubilize the CaCO3 and increase its rate of downward movement.
D) Conservation tillage would increase the pH of the subsoil.
E) Aluminum toxicity would increase in the vicinity of the limestone.
Question 3Which of the following trees would you expect to fare most poorly in a soil at pH 5.0?
A) aspen B) loblolly pine C) walnut D) sumac E) white spruce
Question 4It is common for some plants growing on a particular soil to suffer from a micronutrient deficiency while other plants growing on the same soil are well supplied with the nutrient in question.
Indicate whether the statement is true or false
Question 5Which of the USDA land use capability classes (LUC) is most suitable for the production of row crops?
A) VI B) IV C) VIII D) II E) I
Question 6The U.S. Department of Agriculture has developed soil-loss tolerance limits (T values) for different soils. Which of the following is the highest T value assigned for most soils in this country (Mg/ha)?
A) 15 B) 2 C) 5.0 D) 11 E) 20
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