Question

The different pools of potassium in soils are
(A) Soil solution K
(B) Fixed K
(C) Exchangeable K
(D) Lattice K

• A. (A), (B) and (D) only
• B. (A), (B) and (C) only
• C. (A), (B), (C) and (D)
• D. (B), (C) and (D) only

Hint:

All four forms—solution, exchangeable, fixed, and lattice—represent different potassium availability levels.

Answer 1

The Correct Option is C

Potassium exists in soils in four pools: soil solution (readily available), exchangeable, fixed, and lattice (mineral form). All contribute to K dynamics in soil.

Answer 2

Conceptual approach:
Soil potassium is best understood as a single dynamic continuum rather than four unrelated categories. Solution K (immediately plant-available) is in constant equilibrium with exchangeable K held on clay/organic colloid surfaces; when solution and exchangeable K are depleted, fixed K trapped between clay layers can slowly release to replenish them; and lattice K, locked inside primary minerals such as feldspars and micas, weathers over long timescales to feed the fixed and exchangeable pools. Because each pool feeds into the next along this equilibrium chain, none of the four can be dropped from a complete description of soil K.