Helmut, aren't you in soil? What soil?
Your trying to stay organic?
How about you add an amount of dolomite lime to the soil before you start and mix it in well = no liquid Ca/Mg needed!
So why change over anyway? Really man, what your using is plenty fine! you are not hurting anything by using a single combined supplement in Ca/Mg!
Trust me here! Your not doing things to "need" a single serving Ca or Mg!