In acid soils the principal chemical form of phosphorus available for plant uptake is ________. ...

In acid soils the principal chemical form of phosphorus available for plant uptake is ________.
 
  A) P2O5 B) P3- C) H2PO4- D) HPO42- E) P3+

Question 2

Other things being equal, a soil with 30 clay of the ________ type would be expected to have the greatest potassium -fixing capacity.
 
  A) 1:1 B) allophanic
  C) 2:1 D) crystalline iron oxide

Question 3

Other things being equal, a soil with 30 clay of the ________ type would be expected to have the greatest phosphorus -fixing capacity.
 
  A) 2:1 B) crystalline iron oxide
  C) 1:1 D) allophanic

Question 4

A farmer started irrigating a soil some 10 years ago but in recent years yields have declined and the soil physical condition has deteriorated. Which of the following most likely accounts for this situation?
 
  A) failure to use conservation tillage to reduce salt accumulation at the soil surface
  B) high SAR of the irrigation water
  C) high content of Ca and Mg in the irrigation water
  D) excessive drainage of the soil
  E) high gypsum content in the soil

Question 5

Non-point source losses of which element are considered to be a serious water pollution problem because the resulting high concentration of the element in stream water is toxic to most fish.
 
  A) phosphorus B) potassium C) both A and B D) neither A nor B

Question 6

The amount of P lost from agricultural soils by the process(s) of ________ is generally considerably greater than the corresponding losses of potassium.
 
  A) leaching
  B) gaseous evolution
  C) harvest removal
  D) both B and C are correct
  E) none of the above are correct