If you are doing organic gardening, I would like to share a couple of ideas which I do for my soil in addition to my organic compost.
Some time ago, I did a post on saving your egg shells - I do this on a regular basis, then dry them thoroughly and then grind them to a fine powder to put into my container grown veggies as a source of calcium for the plants - especially for tomatoes and peppers which can get blossom end rot if there is not sufficient calcium available in the soil.
Banana peels are also something that I dry and grind up and put into the soil to provide potassium for the plants -some people just throw the soft peels directly into the soil, but by drying the peels and grinding them up makes it easier for the plant roots to get the potassium.
Magnesium is also something necessary for healthy plant growth and many people use Epsom Salts as an addition to the soil.
However, if your soil has good organic compost mixed in, plus some worm castings and worm tea, there will be plenty of magnesium in the soil and therefore no need for adding Epsom Salts.
It can be used as a short term fix if plants are showing signs of a lack of magnesium - but you need to then look at your soil because that is where the actual problem lies.
