Knowledge from Olle Garden Bed: 6 Compost Accelerators to Fire up Your Pile

In nature, the decomposition of plant and animal substances into rich and fertile topsoil is a very, very slow process. Somewhere in the process, at least as early as the early Roman Empire, intelligent and impatient humans discovered how to copy this process and greatly accelerate it. The following content also has some reference value for raised garden beds.

The basic principle of productive composting is to achieve an appropriate volume, achieve an appropriate balance between carbon and nitrogen, always keep wet, and often turn over. Following these four rules, you do not need any type of compost activator.

However, when your compost pile is inexplicably slow and inactive, or has been forgotten and ignored for a long time, there are some ways to wake up the sleeping compost and kick it into humus.

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Why doesn't my compost heat up?

Compost will decompose most effectively between 150 ° F and 160 ° F (65 ° C to 71 ° C). This temperature range is hot enough to kill pathogens and weed seeds, but not hot enough to kill beneficial microorganisms in the pile.

In order to heat the compost and maintain high temperature throughout the composting process, it requires:


Smaller composts do not retain heat as efficiently as larger composts. Slow composting can be reactivated by adding more material until the pile reaches a minimum size of 3 cubic feet.


The compost heap should be kept moist, but not saturated. Ideally, it will always contain 40% to 60% moisture - about the consistency of a wrung sponge.


The more frequently you flip the stack, the faster it boils. The compost pile that is turned every day will produce the completed humus within two weeks. Every other day for three weeks. Every three days, one month.

Carbon: nitrogen ratio

In most cases, the reason why the compost stack is slow to crawl is the improper balance between nitrogen and carbon materials in the pile.

The ideal ratio of brown to green is 30 parts carbon to 1 part nitrogen.

The ideal ratio of brown to green is 30 parts carbon to 1 part nitrogen.

This can be difficult to measure because not all browns contain the same amount of carbon. For example, chopped cardboard has a very high carbon nitrogen ratio (about 350:1), while the carbon content of dry leaves is relatively low (60:1).

Some people find it easiest to add the same amount of brown and green, and adjust the amount as they go. Others prefer a more precise method, throwing 2 to 3 barrels of carbon per barrel of nitrogen.

Finding the right balance is not too difficult, because the compost heap will always tell you what it needs. If there is too much nitrogen, the reactor will start to smell; Too much carbon and decomposition will greatly slow down.

Repairing slow piles is usually as simple as adding more nitrogen rich material to the pit. Nitrogen provides protein for rapid reproduction of microorganisms working in the pile. The more microorganisms decompose the material, the faster the compost is produced.

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Six compost activators provide fuel for your pile

  1. Urine

Each of us has an underutilized but excellent source of nitrogen. And it's free, ready to use and renewable!

In fact, human urine is a wonderful natural fertilizer and compost stimulant. In fact, the urine of all mammals plays an important role in the nitrogen cycle of the earth.

Although human urine is composed of more than 90% water, the rest is composed of organic solids, mainly urea. Urea is widely used as fertilizer in agriculture.

The average N-P-K value is 11-1-2.5, and our urine contains a lot of nitrogen. Adding this liquid gold is easily the fastest way to stimulate cold composting.

As long as you are healthy and do not take medicine, it is completely safe to urinate on compost.

The best time to let it rain is in the morning, when the urea level will reach the highest concentration.

  1. Grass chip

The new mowing added to the compost pile will immediately turn the slow pile into a mass of heat.

The N-P-K value of grass is 4-1-2, when it is still green, wet and fresh. It loses its nitrogen content when it dries, so it is best to throw the grass cuttings into the compost immediately after mowing the lawn.

Once the cut grass is decomposed in the pile, it will quickly decompose. Although this is a good thing for providing fuel for microorganisms and heating them, grass consumes a lot of oxygen when decomposing. In addition to the tendency to stick together and form lumps, grass cuttings can also create anaerobic conditions that cause the entire compost to smell.

It is very simple to avoid this situation by adding the swarf to the pile before thoroughly mixing it with the brown material. The target is at least 2:1 carbon grass newspaper clipping ratio.

Once the grass is in the compost, turn it over after the first 24 hours. In the next few days, please continue to turn it frequently to prevent the grass from gathering together. Regular aeration can also make newspaper clipping better distributed in the whole pile.

  1. Blood powder

The N-P-K of blood powder is 12-0-0, making it one of the most abundant sources of organic nitrogen.

Animal blood is a by-product of the slaughterhouse, which is collected and dried into powder. It is usually used as early season fertilizer to promote explosive growth of plants in the garden.

Sprinkle it on the soil to quickly improve the crop. This is a powerful thing. If you overuse it, it will burn seedlings, so always use light hands to smear it

When working in the soil, the blood powder will emit a smell that we can hardly detect, but it is very useful to prevent rabbits and other small animals from chewing crops.

Blood powder is also the perfect foil for sleepy compost. Especially when you have a lot of carbon rich yard garbage and do not have enough vegetables to match, blood meal can be the only nitrogen provider in the pile.

To handle a pile of leaves or woody material, apply blood powder at a rate of 2.5 ounces per cubic yard of carbon material.

Adding blood powder to compost that already contains some green vegetables requires more guesswork because you don't want your C: N ratio to get out of control. Start small - only a teaspoon or two - and pile them up. If the compost is not heated within 24 to 48 hours, add a little more.

  1. Alfalfa

Medicago sativa is a very useful small plant.

Alfalfa is a member of leguminous plants and pea family. It is a flowering perennial herb with many amazing qualities.

As a nitrogen fixing agent, planting alfalfa together with other plants can help improve soil fertility.

Alfalfa blooms beautiful lavender flowers from June to September. These flowers are very attractive to pollinators and other beneficial insects throughout the growing season. Birds like alfalfa, too.

On the homestead, the nutrient rich leaves of alfalfa provide excellent feed and fodder for chickens, ducks, goats, sheep and many other barnyard grass animals.

At the end of the season, alfalfa plants can be pulled out, chopped, and then added back to the soil as green manure.

Whether planted fresh in the garden or purchased as alfalfa powder, it is a great universal fertilizer, N-P-K is about 3-1-2. These nutrients are slowly released into the soil, making alfalfa warm enough to be used for the youngest seedlings and buds.

Because of its high nitrogen content, alfalfa is a good ingredient for composting cooking. Alfalfa powder can be actively used for heating piles by sprinkling it between the brown and green layers. To light a pile of slow speeds, add one or two before taking turns.

  1. Feather powder

Believe it or not, bird feathers are a very rich source of nitrogen.

Birds' feathers are composed of about 90% keratin, and the nitrogen content is between 12% and 15%.

Although feathers are fibrous, insoluble, and resistant to degradation outside the compost, they will be exposed to keratin decomposing microorganisms in the pile, which will completely decompose them.

If you raise backyard chickens or ducks, you will surely have endless molts to feed compost. Old down pillows, duvets or jackets may also be stolen to store the fluff inside.

When composting "fresh" feathers to heat a pile of feathers, soak them in a bucket of water for 24 hours before throwing them in. This step will not only make them heavier, so they will not be blown away by the wind, and the pre soaked feathers will help them decompose faster.

If you don't have bird feathers, feather meal is also an option. The 12-0-0 slow-release fertilizer is made by heating and disinfecting poultry feathers with a steam pressure cooker. The feathers are then dried and ground to powder.

To use feather powder as a compost activator, add about one cup to start. Wait for the necessary 24 to 48 hours. If the pile does not get hot, please throw it into another cup.

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  1. Waste coffee grounds

Whether to use - or not to use - coffee grounds in the garden has recently become a hot topic in the field of organic gardening.

On the one hand, used coffee grounds are an important source of nitrogen, which will surely awaken the sleepy compost heap.

It contains about 2% nitrogen. The by-product of morning coffee is a very valuable green material. Composting can prevent it from entering the landfill. It's also easy to get - people who don't drink coffee can buy bags of used coffee grounds from the local coffee shop.

On the other hand, the scientific investigation of coffee grounds as fertilizer, mulch or compost into garden soil has yielded mixed results.

In one experiment, composting coffee grounds promoted the growth and yield of sugar beets, cabbage and soybeans, while in another experiment, it hindered the development of alfalfa, clover and Chinese mustard.

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As a guiding principle, Dr. Linda Chalker Scott, a master gardener at Washington State University, recommends keeping the total amount of coffee grounds in the compost between 10% and 20%. Any coffee grounds higher than 30% will increase the risk that these coffee grounds may eventually damage the microorganisms and earthworms in the work pile.

An informal field experiment conducted by Oregon State University Extension Service found that compost consisting of 25% coffee grounds was most effective in maintaining sustained high temperatures. Waste coffee grounds are much better at maintaining composting temperatures from 135 ° F to 155 ° (57 ° C to 68 ° C) for at least two weeks than manure.