Advanced Soil Chemistry Solved Question Form Six Pdf
ADVANCED SOIL CHEMISTRY SOLVED QNS
FORM FIVE AND SIX FIRST EDITION QUESTION
1. Determine the CEC for the soil that contains 10% humus (200cmol/kg),
40% smectite (100cmol/kg), 5% gibbsite (40cmol/kg). (where cmol/kg in bracket
of each constituent represent CEC of pure component).
Solution
CEC contribution of humus CEC contribution of smectite = 2cmol/kg CEC
contribution of gibbsite = 2cmol/kg Then, CEC of the soil = 20cmol/kg +
2cmol/kg + 2cmol/kg = 24cmol/kg. CEC of the soil is 24cmol/kg QUESTION 2 A
sample of clay surface soil is taken from a Mr Njige farm and analyzed in the
laboratory. The laboratory results indicate a CEC of the soil is 20cmol/kg and
the following concentration of exchangeable cations: Ca2+ = 3cmol/kg, Mg2+ =
4cmol/kg, Al3+ = 4cmol/kg, H + =6cmol/kg, and K+ = 3cmol/kg. Mr. NJIGE-E
0711614882/06
