Eggshells are one of the most common organic waste products found in our environment. They have been used since ancient times as food and medicine. Their use was restricted after World War II due to their high toxicity level, but they were reintroduced into some areas such as Japan where they are still being used today.
The main purpose of using eggshells in compost is to increase soil fertility and to provide nutrients for beneficial microorganisms. However, it’s not just about increasing fertility; it’s also about controlling pests. Eggshells contain calcium carbonate which acts like a natural pesticide against certain types of insects and other organisms.
When egg shells are broken down, the calcium carbonate forms small crystals called “eggshells”. These tiny eggs are then released from the broken shell when crushed or mixed with soil. When these tiny eggs break down into smaller pieces, they become part of the soil.
There are two types of eggshells: hard and soft. Hard eggshells require special handling methods to prevent them from breaking apart during processing. Soft eggshells can be easily handled because they don’t crumble easily.
These are the steps in preparing eggshells for use:
Wash the eggshells, and then pat dry with a clean cloth. The next step is to put these shells in a container and crush them with a rolling pin. A food processor can also be used but be sure not to over process the shells into a fine consistency.
The next step is to spread the shells out on a tray and let them dry completely in a well-ventilated area. The shells should be dry enough so that they do not stick to your fingers when you touch them. These dried eggshells are then ready to be added to the compost bin or used for pest control.
Eggshells are rich in many vital nutrients including:
Calcium – This element is important for plant cell growth and the maintenance of solid stems and roots. It also plays a role in promoting healthy flowers and preventing plants from getting diseases.
Phosphorus – This element is important in the metabolism process. It helps plants produce healthy flowers and fruits.
Riboflavin or Vitamin B2 – This vitamin promotes the production of enzymes and helps in flowering.
Eggshells also contain trace amounts of various other nutrients such as: sodium, magnesium, zinc, iron, copper, manganese, potassium, selenium, and silicon.
Eggshells can be used in the garden in two different ways:
1. Liquid Eggshells – These shells are crushed and then added to a bucket of water.
This mixture is then sprayed on the leaves of the plant using a spray bottle. This should be done early in the morning or late in the evening so that the plants can absorb all the nutrients before nightfall.
2. Dry Eggshells – These shells are crushed and added directly to the soil.
They help improve the soil’s structure, drainage capacity, water retention capacity and nutrient holding capacity. They also provide long lasting nutrients to plants.
It is best to crush the shells before using them in the soil or on the plant because this will prevent them from breaking into smaller pieces when you add them to a hard surface like concrete or a stone walkway. You can also crush them with your hands before applying them to the soil or spray them directly on the plant.
Did You Know?
Eggshells are calcium-rich, and slugs love calcium. To get rid of slugs in your garden or compost bin, smash a few eggshells and leave them in the area you want to protect. The slugs will eat the calcium-rich shells and die.
Sources & references used in this article:
Feasibility study on windrow co-composting to recycle industrial eggshell waste by MJ Quina, MAR Soares, AA Ribeiro… – Waste and Biomass …, 2014 – Springer
Co-composting of eggshell waste in self-heating reactors: Monitoring and end product quality by MAR Soares, MMJ Quina, RM Quinta-Ferreira – Bioresource technology, 2013 – Elsevier
Organic biowastes blend selection for composting industrial eggshell by-product: experimental and statistical mixture design by MAR Soares, SR Andrade, RC Martins… – Water Science and …, 2012 – iwaponline.com
Residues of chromium, nickel, cadmium and lead in Rook Corvus frugilegus eggshells from urban and rural areas of Poland by G Orłowski, Z Kasprzykowski, W Dobicki… – Science of the total …, 2014 – Elsevier
Treatment and agricultural valorization of eggshell. by MC Magalhães, A Ribeiro, M Quina… – Revista de Ciências …, 2011 – cabdirect.org
Intra-clutch and inter-colony variability in element concentrations in eggshells of the black-headed gull, Chroicocephalus ridibundus, in northern Poland by I Kitowski, P Indykiewicz, D Wiącek… – Environmental Science and …, 2017 – Springer