Reading the results of Dr. Whitcomb's extensive tests on the germining and growing of tree seedlings in his book "Plant Production In Containers 11" I found the following information concerning the addition of dolomite to the growing/germinating medium of young seedling trees. >>>>Dolomite should be added ONLY if the irrigation water supplies less than 25ppm calcium and then only at a rate of about 2 to 3 pounds per cubic yard or less.<<<<< The book goes on to say that the addition of calcium/magnesium above the amount required actually retards the growth of young seedlings. - Millet