How to calculate base saturation?

Hi I'm trying to figure out how to calculate base saturation from the practice midterm 3 question 1 A. I know the equation is %BS=(weird symbol)x(Ca2+ Mg2+ K+ Na)/ CEC X100, but I'm having trouble actually understanding what that means and how to do the calculation. Such as what does that symbol at the front mean? Do we use the percentage/decimal value of Ca, Mg, K, and Na on the top line? How do we know the CEC value on the bottom line? Additionally, I know that low BS = low pH and High BS= high pH but what is the reasoning behind this? Thank you for your help I really appreciate it!

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Hi Kristi

%BS = the SUM of (Ca²⁺ + Mg²⁺ + K⁺ + Na⁺) / CEC x 100%

So, for question #1 on the 2018 midterm #2 you are given the percentage of exchangeable cations, i.e. their proportion of CEC. Note these total to 100%, implying that there are no other cations in this simplified soil system. The CEC = sum of all cations (i.e. 100%). Thus you can determine part a) the % B.S.

For part b) consider what is held on the exchange sites in addition to the 4 bases. The relative proportion of base forming cations versus acid forming cations will give the answer to b) where this soil would have an acidic or alkaline pH.