A cover crop is usually grown for the purpose of:

A cover crop is usually grown for the purpose of:
 
  A) saving or recycling nutrients.
  B) improving soil quality.
  C) covering expenses for pollution control measures.
  D) both A and B
  E) all of the above

Question 2

The very high pH levels found in some arid region soils are most likely due to high levels of exchangeable ________.
 
  A) Al(OH)2+ B) Mg2+ C) Ca2+ D) Na+ E) Al3+

Question 3

In humid regions repeat applications of limestone are needed after a few years primarily because of:
 
  A) increased rates of formation of carbonic acid (H2CO3).
  B) the release of aluminum ions from the structure of silicate clays.
  C) increases in phosphate fertilization.
  D) the annual loss of calcium and magnesium in drainage waters.
  E) increases in soil acidity from acid rain.

Question 4

How does the amount of lime needed to neutralize the residual acidity in a clay loam soil compare to that needed to neutralize the active acidity in that soil?
 
  A) residual requires about the same
  B) residual requires 5,000 times greater
  C) residual requires 10 times greater
  D) residual requires considerably less
  E) residual requires about double

Question 5

The drainage of certain wetlands has resulted in extreme soil acidity. This is due primarily to which of the following processes that take place when the soil is drained?
 
  A) reduction of iron to low valent states that stimulate acidity
  B) oxidation of organic materials to produce organic acids
  C) release of nitric acid due to oxidation of nitrogen compounds
  D) high redox potential characteristic of aerated soils
  E) oxidation of sulfur-bearing minerals that produces sulfuric acid