While a fellow gardener and I were sharing gardening experiences the other day, he mentioned that he had added too much nitrogen and caused blossom end rot. This is a very common problem with tomatoes. A spot begins to rot where the blossom was originally attached (opposite from where the stem attaches). I replied that it is calcium deficiency that causes blossom end rot.
It turns out that we were both right. The March/April issue of National Gardening Magazine quotes Ohio State tomato physiologist Dale Kretchman, “Nitrogen fertilizer will encourage lush top growth , at the expense of the root system. The plant will get too big for its roots to supply it with other nutrients and water, and you set the stage for blossom end rot, which is really a response to calcium deficiency. There is no doubt that gardeners [in the USA] fertilize their tomatoes too much.”
ECHO Staff 1993. Blossom End Rot on Tomatoes. ECHO Development Notes no. 41