Sandy soils have a very low cation exchange capacity because they contain little:

1. Cation exchange capacity measures how many cations a soil can hold on its particle surfaces. 2. The holding is done by negatively charged sites, which sit on clay and humus colloids. 3. Sandy soils are made of large quartz particles carrying almost no such charge. 4. With little clay and little humus, there are almost no exchange sites available. 5. So the capacity approaches zero, and nutrient cations wash straight through instead of being retained. _Source: NECTA ACSEE 2024 Chemistry 132/1, Question 8: Soil Chemistry and Environmental Chemistry_