13 Common Myths of Composting

Before stating your own pile, it is important to get the facts straight on what a compost pile is, how it works and all the do’s and don’ts. This task can be overwhelming, so we’ve gathered our top 13 tips to help you get the compost started.

Myth #1: Start a compost pile to manage grass clippings

Why not try mulching before composting? Making piles of organic materials is more work than letting them lie. Instead of bagging, why not try “Grasscycling” or the “Don’t Bag It” system of using mulching mowers instead? There is no reason to bag grass if you cut it more often, use less fertilizer and leave the grass higher. Composting (making piles) is a last resort in terms of managing grass clippings and should be practiced only when mulching is not practical, unless you want to make compost.

Myth #2: A compost bin is a compost bin

Not all compost bins are the same. You might regret purchasing or building a compost bin that is not suited to do what you want the bin to do. For table scraps, for example, you might consider a worm box instead of a compost bin. Some people believe they can just let their organics sit for years without ever bothering with a bin at all! A pile serves to create:

1. Heat
2. Moisture

If your goal is to “hold” materials such as leaves for a year or so, a large open-air holding bin is most practical. For active, hot composting, smaller enclosed plastic bins are preferred. Bins with sidewalls may make turning more difficult. Wire bins may rust and decompose quickly.

Myth #3: Form layers in the bin

Even if you are using a passive composting system, it is better to mix ingredients together outside the bin first. Nearly every other composting guidebook or brochure has a picture of layers of organics inside the compost bin. The point these guides are missing is that organics should be layered and moistened outside the bin, not inside of it. The act of forking everything over into the bin, mixing it all together as it goes, is the key, missing step. Layers of organic material will not cook or heat properly until they are mixed. While it may seem that mixing materials together is extra work, this initial mixing stage can eliminate the bothersome job of turning a ripe pile in order to mix it later. It is better to mix at the beginning, before stuff gets stinky.

Myth #4: Add topsoil to inoculate the compost pile

Old compost is a better inoculate than topsoil. Adding soil to a compost pile is like adding soil to a campfire; it puts the fire out! Soils are mostly minerals and add little other than weight to the pile, making it more difficult to turn and use. Topsoil adds no “fuel” to help the composting “fire.” The idea behind adding soil is to inoculate the pile with a healthy culture of soil organisms that colonize the pile and “jump start” the active, hot composting process. The best source of this inoculant, however, is older compost. The trick is to always save some old compost from previous batches to mix in with the fresh material.

If this is your first pile, try old leaf mold from under trees. If that is impractical, buy a few bags of composted manure from the garden center. Adding a little packaged inoculant may help if it contains an active biological culture. A rich, loamy garden soil should be used only as a last resort for the very first pile, never as a standard ingredient.

Myth #5: Add lime

There is never a need to add lime to a compost pile. It can actually make things worse. Compost goes through natural pH changes, including an acidic stage while the pile is active, and a sudden rise in pH from adding lime can actually kill a whole generation of beneficial organisms. Lime also has the disadvantage of releasing and losing valuable nitrogen, which can actually create a foul ammonia smell. Lime may be added to acidic soils, but it serves no beneficial purpose in the compost pile.

Myth #6: Don’t add items that contain toxins

Everything that was once alive will eventually decompose back into humus. It is impossible to determine what plant or animal products comprise the humus by analysis. Natural chemicals found in plant (walnut leaves, eucalyptus, oleander) matter that are toxic to plants or animals eventually degrade, and composting accelerates this decomposition process. For example, just because a plant such as rhubarb contains oxalic acid that may be toxic to humans does not mean that the compost made from this plant matter will be toxic to plants. In fact, the research shows that it is not.

Myth #7: Build your bin on soil so microbes can enter the pile

Most commercial compost operations work just fine on top of concrete and asphalt. The number of microbes that will enter the pile from beneath it is insignificant. Add microbes in the form of old compost as an inoculant when the compost ingredients are mixed instead.

Myth #8: Add earthworms from the garden to the compost pile

If the pile is just being started, the heat may kill the earthworms. Garden earth worms do little to assist the composting process compared to their cousins, the redworms. Not all worm species are identical, and in fact, of the over 1,800 species of earthworms found around the world, only two species of redworms are used regularly to assist the composting process. These beneficial redworms must be acquired from a worm grower and added after the pile has cooled, and then the pile has to be kept properly moist.

Myth #9: Composting is what nature does with organics

Nature does not build piles; nature mulches in layers. Composting is a “pile making” behavior characteristic of humans which converts organic materials into dark, crumbly stuff so that it can be converted back into a layer, as nature intended. Composting is perfectly “natural,” but piles are not nature’s way of degrading organic materials into humus.

Myth #10: Adding ’such and such’ accelerates composting

Composting can never be accelerated; it can only be delayed. There is an optimum rate of decomposition that occurs when moisture, air, temperature and nutrients are properly balanced and blended. If any of the essential components to decomposition are out of balance, the decomposition rate can be slowed.

Since most people practice passive composting where organic materials just sits there, they think that composting takes longer than it really should. When they add moisture, mix ingredients, inoculate, retain heat or do other activities that optimize the decomposition process, they naturally think that they have “sped up” the composting process. In fact, they have merely eliminated some of the delays. Composting rates may be relative from batch to batch, and some materials decompose more quickly than others.

Keep in mind however, that humus produced from slow decomposition is just as beneficial for the soil as organic matter produced from the best of the hot composting piles. It is your decision and management skills that determine how quickly or slowly your compost is finished. Fast is not necessarily better.

Myth #11: Don’t add grass clippings that contain herbicides

Grass clippings, even those treated with over-the-counter herbicides are safe to use for composting. Even without composting, the common household herbicide 2,4-D is not significantly toxic to established plants after a week or so. Fresh clippings may retain some high levels of herbicide if they are used as a mulch. Compost, however, is rarely used until six months or a year after it is made. Studies have shown that 2,4-D degrades 87 percent within ten weeks in the compost pile. Other studies show them to be non-detectable after six months.

Myth #12: Don’t add paper, it contains toxic metals and inks

Paper products are safe to use in the compost pile. Numerous tests have been conducted of various grades of mixed paper and the heavy metal levels are virtually the same as a variety of other ingredients. All plant matter contains trace amounts of heavy metals, and the U.S. EPA has set limits regarding the concentrations of a variety of metals that can be safely used in the soil. Paper products are well below these levels.

Regarding the inks themselves, the amount of hydrocarbons in the ink is insignificant, and the composting process is widely used as a technique by bioremediation specialists for degrading a variety of hydrocarbons. The tiny amount of hydrocarbon solvents in paper will be quickly degraded in the compost pile. Soy inks are used not to reduce toxicity of the paper, as much as to promote the use of renewable resources over non-renewable fossil fuels.

Myth #13: Black dirt or topsoil is better than compost

Organic, fertile soils are living ecosystems that took thousands of years to become fertile by Nature’s process of annual mulching. When people move into a new frontier, the soils are rich in organic matter and are highly fertile. Once depleted, however, a process that can occur in a few years or generations, it will take thousands of years to enrich the topsoil with organic matter again. We can accelerate this process of building up soil fertility by tilling in compost, creating living soils in a fraction of the time. Enrich the soil you already have with compost or remove the old soil and replace it with soil mixed with compost.