I'm getting confused.....I thought limestone was calcium carbonate with just a small amount of magnesium unless you were using dolomite lime which is hi magnesium.I think calcium leaches out of soil easier than magnesium. What I know is that I was told repeatedly that my farm did not need lime, but grain and forage yields both significantly increased when I applied calcium carbonate. I had two spots that grew foxtail every year, no matter what I planted. Eventually I discovered those two spots were the highest spots on the farm in magnesium.