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What Not To Compost: Here Are 7 Things You Should Avoid At Any Cost

compost pile

Creating a compost pile in one of the basic steps you can take for organic gardening. But people often get confused on what to compost what not to compost. In our earlier article, we have discussed what can be composted. This article is all about what not to compost.

If you had read the earlier article you know that most of the products that we see around us can be composted. But to make the process of composting smooth and to prevent any unwanted impacts on the plants we should shun some elements in the process of composting. In this article, we will discuss what not to put in your compost pile.

7 Things That You Should Never Add To Your Compost Pile

what not to compost

Followings are the seven things you should never put in a compost pile.

  1. Coal/Charcoal:

coal in compost

Avoid coal or charcoal ashes. They are known for their slow decaying rate. This is the reason why archaeologist used charcoals for calculating the age of ancient and prehistoric materials which are more than a thousand years old.

So when our basic purpose is to decompose the materials quickly, it makes sense to avoid such material. Besides coals sometimes contains an excessive amount of sulfur and iron which can be toxic to most of the plants.

So just to fill the gap created by shrinking of the compost pile don’t add charcoal or coal ash. The impact might not be as good as you have predicted.

2. Colored Papers:

glossy papers in compost

Colored, glossy papers usually contain chemicals which sometimes infested with heavy metals such as Lead or Mercury. These chemicals can be very lethal to the well being of the plant as well as for the person who will consume the crop.

Though nowadays governments around the world have made strict laws to prevent the use of heavy metals in the production of color pigments, we are never quite sure about the contains.

So if you are interested in using papers, use the white ones. Paper is basically cellulose so it will break down slowly. Add the paper in a small amount and prevent it from forming a layer by spreading them throughout your compost pile.

3. Diseased Plants:

diseased plants in compost

It is basically common sense to avoid diseased plants or part of them. The pathogens present in the plants can sometimes survive the heat generated by the compost pile and then it can cause a fresh attack on the plants where you are putting your compost.

Potato tubers which are affected by wart diseases or the stalks affected by sclerotia should not be put inside the pile. Cabbages affected by club root, celery leaves with blight, onions with mildew are some of the examples of the diseased plants which are very hard to destroy and only an “ideal compost pile” provide the necessary condition to destroy these pathogenic organisms.

So if you have any doubt about the steady heating of your compost pile it is better to avoid these plants.    

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4. Pet Droppings:

cat-droppings-compost pile

Cats and dogs droppings contain disease-causing pathogens. Cat droppings, in particular, contains nematodes and other parasites which can enter through the mouth and can cause eye or brain diseases.

This is also the reason why children and pregnant women are advised not to handle cat litter.

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5. Non-biodegradable Items:


As the name suggests they are not going to get decomposed in the pile. Materials such as plastic, aluminum, and other metals, glass, synthetic fibers etc. are not going to add any value to your compost heap.

Though they are not necessarily toxic to the plant it will remain as it is and would be of no help in the composting process.

Real rubber is through organic in origin and biodegradable, the rate of degradation is pretty slow. So it should also be avoided.

6. Sludge:

sludge in compost

If you live in a place where there is little or no industry, the sludge from your sewage is may be safe to use in the compost. None the less, it is not a very good idea to use sludge in your compost.

Most of the time the toxic materials get infested in the sludge and can cause disaster for your garden. Most of the gardening experts also recommend not to use them.

If you are getting treated sludge which is available commercially in different garden centers you may use it but make sure these are treated under EPA’s (Environmental Protection Agency) guidance.

7. Toxic Chemicals:

Never put insecticides or pesticides inside the compost pile. It will kill those organisms which conduct the process of composting.

As an organic gardener, we should always be at a safe distance from those hazardous chemicals.

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