Eggshells are 93% calcium carbonate. In addition to the calcium, the eggshells contain about 1% nitrogen, about a half-percent phosphoric acid, and other trace elements that make them a practical fertilizer. Calcium is an essential plant nutrient which plays a fundamental part in cell manufacture and growth. Most roots must have some calcium at the growing tips. Plant growth removes large quantities of calcium from the soil, and calcium must be replenished, so this is an ideal way to recycle your eggshells.
Dry out the shells, then crush them by hand and powder them in a blender. Place powdered eggshells around fruit trees, in potted plants and roses, and throughout a vegetable garden.
