What beneficial thing does eggshell do to tomatoes as a fertilizer? Does it heal leaf health, flowers, taking up nutrients, or something else?


Eggshells are a calcium source. Tomatoes need sufficient calcium in the soil to prevent blossom end rot.

Oyster shell and egg shells are a source for slow release calcium as they need to break down in order to make it available. Composition for both of these is mainly calcium carbonate crystals.

General usage of calcium soil amendments: If you determine you need calcium because the fruits are developing black rot on the blossom end, you will need to test the soil pH to determine whether you can add lime (Calcium Carbonate) which raises pH or add gypsum (Calcium Sulfate) which is more pH neutral. Lime helps make the soil less acid, gypsum is more appropriate for soil that is within the target pH range for the type of plant you're growing.

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    Lime is valuable in the correct dose, but there's an old farming rhyme in my part of the world: "Lime and lime and no manure, makes fathers rich and children poor". Lime helps to release many different nutrients and trace elements in the soil in the short term, but it doesn't replace any of them for the future. Use it as part of a "balanced diet" for your plants, not just on its own. – alephzero May 15 '16 at 6:00
  • @alephzero - It's why soil testing for nutrients is a really good idea. Adding any one thing can shift soil acidity/alkalinity, poison the soil or just plainly harm the soil ecosystem so that the microbial environment that makes nutrients available dies. Your saying has a very basic nasty truth to it. As you lime, the soil becomes devastatingly alkaline and as you add manure, potassium builds up till it stunts plant growth. – Fiasco Labs May 16 '16 at 3:46

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