The primary issue when planting a tree that prevents it from taking off and being healthy is a lack of calcium in the soil. Insufficient levels of calcium cause the soil to compact and not allow roots to expand. If you've planted a tree that has not survived and dug it up, did you find that the roots were still in their original ball formation? This is the situation that I am referring to.
Calcium combines with the components in the soil and causes them to become smaller in their structure. This looser soil structure allows for the roots to have room to spread out. In areas that have high clay content, the roots can now stretch out into cracks in the soil and establish themselves further out. Clay also has many microscopic pockets that hold nutrients, so expansion in this type of soil is now doubly beneficial.
Add to this equation a little bit of sulfur and you now have a combination that will build strong cell walls as your roots expand and gather nutrients. The Garden Vigor product Sulf-O-Cal
is calcium sulfate, which is also known as gypsum. It is a very fine grind of recycled wallboard. When placed in the hole before planting, Sulf-O-Cal 'softens' the soil and provides nutrients that your seedlings need to thrive.