Assume that for each 1% of it’s respective content in a respective soil sample,
ID: 291937 • Letter: A
Question
Assume that for each 1% of it’s respective content in a respective soil sample, humus contributes cation exchange potential of 2.0 cmol/kg of soil, smectite contributes 1.0 cmol/kg, and kaolinite contributes of 0.1 cmol/kg. If the soil has a content of 5% humus and 15% clay, plus 90% of the clay is kaolinite and 10% is smectite, which of the constituents (humus versus smectite versus kaolinite) contributes the most cation exchange potential to the soil and the least cation exchange potential? Explain your reasoning.
Explanation / Answer
Cation exchange potential is termed as the ability of the soil to retain positive charges in them in order to hold the nutrients essential for the typical growth of the plants in it. Given that the cation exchange potential in the given sample of soil is 1 cmol/kg for the smectite and 0.1 cmol/kg for Kaolinite and 2.0 cmol/kg for humus. Clay minerals with its association of feldspars contribute a lot due to the ability to hold negative charges on their surfaces. Therefore the ability to hold positive charges on their surfaces would be much greater compared to the other minerals. Therefore smectite would have a greater ability to hold positive charge and hence would have the most action exchange potential. The least cation exchange would be in the case of humus as it's main constituent is organic matter, therefore the extent to which positive charges could be accumulated is very less.