| MadSci Network: Botany |
Eggshells are about 95% calcium carbonate with the rest calcium phosphate, magnesium carbonate, potassium, sulfur, and proteins. Phosphates and carbonates are not very soluble so eggshell water is probably not very high in calcium, magnesium and phosphorus. However, all three plus potassium and sulfur are essential mineral nutrient for plants, so if if any of those mineral nutrients are deficient, eggshell water might be beneficial to plant growth. Calcium carbonate is a liming material, which raises soil pH. Eggshell water could be detrimental if the soil pH is too high already or beneficial if the soil pH is too low. You could measure the eggshell water pH to see how it compares to an ideal pH of 5.5 to 6 for an organic potting soil. Eggshell water might be especially bad for acid soil loving plants such as azaleas or blueberries. If you are doing an experiment, it should be more effective to add crushed eggshells to the potting soil rather than using eggshell water. References What are eggshells made of? Dried Eggshell Composition
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