It protects plants to some degree from nutrient excess and deficiency, and minimizes problems caused by both high and low pH and heavy metal contamination. Along with organic matter, calcium improves soil structure. In the hierarchy of the 16 essential plant nutrients, calcium is seventh and sulfur is ninth. Calcium does not move from old to new plant tissues, so a constant supply of soluble calcium is needed. Symptoms of calcium deficiency include Water-soaked, discolored areas on fruits, such as blossom end rot on tomatoes, peppers, melons and squash, or bitter pit or cork spot on apples.
Tip burn on young leaves of celery, lettuce and cabbage.
Death of terminal buds and root tips. Abnormal dark green appearance of leaves. Premature shedding of blossoms and buds. Because it is dissolved in the soil solution, gypsum readily migrates into the lower depths in the soil. Most western soils contain abundant calcium, but as very insoluble calcium carbonate.