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Can you put wood ash in compost


How to Compost Wood Ashes

Up here in Vermont, the winters are long.

For me, this means months spent curled up by the wood stove with a book and a cat on my lap.

It also means the creation of a lot of ash – which always leads me back to the question of whether or not I can compost ashes.

As it turns out, the answer is yes, with a couple of crucial caveats.

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This article will explore how to use wood ashes in the compost and in your garden, and when it is appropriate to do so.

What You’ll Learn

Benefits of Wood Ash

Wood ash from your fireplace contains a number of nutrients that can be very beneficial to a garden – in the right circumstances.

But never use the ash from charcoal, trash fires, or treated wood, which can contain toxic chemical residue from additives.

Wood ash contains potassium and calcium in considerable quantities, as well as lesser amounts of magnesium and phosphorus, and micronutrients such as copper and zinc.

Due to its high level of calcium, it can increase the pH of soil, making it an ideal natural substitute for lime, an amendment often used to balance soil that is too acidic.

It can be a very useful amendment where acidity is too high for growing most veggies, in a pH range of 6.0 and below.

But you’ll need to be cautious. If the soil is already neutral or alkaline, adding ashes will cause excess alkalinity and add soluble salts, ultimately doing more harm than good.

So how do you know when it makes sense to add ashes to your compost or garden?

Let’s explore.

Test Your Soil

Before adding ashes (or any other amendment, for that matter) to your garden, be sure to get your soil tested!

You can easily request a test through your local agricultural extension office.

You can buy home pH test kits or meters at your local hardware store or online, though I would recommend getting a test from your local extension office at least once.

The results of these tests are more comprehensive and they will tell you a whole lot about your soil, including information about any other nutrient deficiencies.

If you don’t have access to professional testing or a kit, it is possible to DIY a basic test of the pH with just two cups full of soil, some vinegar, and some baking soda.

Pour vinegar into the first cup. If the soil begins to fizz, it is alkaline.

Add some water to moisten the soil in the second cup, then add baking soda. Fizz this time means it is acidic.

This method is not especially accurate, and you won’t be able to determine the exact pH level of your soil this way. It is still a good idea to get a more accurate test when you are able.

In the meantime, however, this simple method should at least give you a general sense of whether the soil is acidic or alkaline.

When to Compost: Timing and Moderation

The key is to add small amounts of cooled ashes to a new or uncooked pile. Because it has such a high pH value, it is important that you don’t add too much to your compost.

According to Olivia Saunders, Extension Field Specialist in Food and Agriculture at the University of New Hampshire Extension, “it should not make up more than 5% of your compost.”

Additionally, once the compost nears maturity, the addition of ash could raise the pH too much, increasing the bioavailability of heavy metals to harmful levels.

How to Compost

Before you start, be sure to suit up with gloves, eye protection, and a mask to avoid any potential irritation to the skin, eyes, or lungs. Also, ensure that the ashes have completely cooled before handling them.

Sprinkle the ash onto your compost pile along with the appropriate ratio of brown and green material.

What does this mean? Add about a quarter inch for each 18-inch section of browns and for every six inches of greens. Be sure to turn the pile each time you add new material.

As a reminder, browns include carbon rich materials such as straw, hay, and dried leaves, while greens are more nitrogen heavy items such as kitchen scraps and fresh grass clippings.

To learn more on the basics of composting, check out this article.

If you have a hot compost pile, add a small amount of ash along with other new materials every month or so while it is active.

If the pile is cold or rarely added to, only add ash in the fall or late summer, allowing time for everything to break down before being used in the garden during the growing season.

You can collect ashes and store them in a covered container through the winter.

Adding It Directly to the Garden

If you have determined via a test that your pH is low – below 6.5 – you can also choose to add ashes directly to the garden to reduce acidity.

Incorporating ashes can also increase the bioavailability of potassium, phosphorus, and various micronutrients, thereby increasing fertility.

A Note of Caution:

Never mix ashes with nitrogen fertilizer, it can cause a reaction that releases ammonia gas. Always wear eye protection, a face mask, and gloves when handling wood ashes.

Spread on calm days to prevent it from blowing around and scattering to unwanted areas – including all over your clothes.

Apply in moderation, lightly dusting a small amount on the garden surface and working it into the soil several inches deep with a fork.

According to Rosie Lerner, Horticulture Specialist at Purdue University, “Acidic soils (pH less than 5.5) will likely be improved by wood ash addition.

Soils that are slightly acidic (pH 6.0 to 6.5) should not be harmed by the application of 20 pounds per 100 square feet annually, if the ash is worked into the soil about six inches or so.”

Be sure to test the soil again the following year. You can reapply if the pH is still too low, but if it has reached 6.5, don’t add any more. If you raise the pH too much, this can deplete the bioavailability of essential nutrients.

Do not apply to acid-loving plants such as blueberries, rhododendrons, or azaleas.

Continue to test your soil every few years and amend as necessary.

Ashes to Dust

While it is never wise to dump a whole bucket on your compost or in the garden beds, used in moderation with careful planning and an understanding of your soil, wood ashes can be repurposed as a useful amendment.

Though my wood stove churns out far more than I can safely use each winter, I am still able to recycle much of it back into my compost.

Have you used wood ashes in your garden? Please share your experience in the comments below!

If you enjoyed this article, you can learn more composting tricks in these guides:

© Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Uncredited photos: Shutterstock. With additional writing and editing by Clare Groom and Allison Sidhu.

Can I Compost Ashes (The Truth about Ashes in Compost)

Understanding if and how you should use ashes in compost can be confusing.

For example, you hear a lot of gardeners using ashes as fertilizer in the soil. So should you just throw it directly onto earth, or is it better to put it in compost?

And if you regularly use a fireplace or stove, you probably accumulate a lot of this waste material. 

So what’s the best way to deal with it?

In this article, I’ll explain the ideal way to include ashes in your home composting and how to avoid the possible side effects of using ash for the garden.

Can I compost ashes?

Ashes are an excellent addition to compost because they are high in potassium and other micronutrients. It helps make compost more versatile for soil amendment. Ashes are also very alkaline and help modify the pH values of compost. But not all types of ashes are ideal for composting.

Ashes are known to be a good source of potassium (they contain up to 10% potash). 

Potassium is needed by plants to create chlorophyll, the amazing substance that makes photosynthesis possible. It can also help make plants more disease-resistant. 

Ash is also high in calcium (up to 25%). Calcium carbonate is a well-known limining material. In other words, it increases alkalinity levels.

On top of that, ashes contain many other valuable micronutrients, such as magnesium, phosphorus, iron, boron, zinc, and manganese.

Compost made with ashes will have an increased spectrum of nutrients. The larger the variety of organic matter you put in your compost, the better it can replenish nutrients in the soil.

One of the beneficial side effects of using ash in compost is that it helps neutralize odors.

You should also know that ashes can strongly affect acidity levels. In addition, they contain soluble salts, which can be potentially harmful to plants. For these reasons, it can be more beneficial to put ashes into a compost bin rather than spreading them directly in the garden.

But a word of warning…

You need to consider the origin of your ashes to ensure they don’t harm your compost and gardening efforts. 

Are ashes bad for compost?

Ashes are generally considered good for composting. This is because not only are ashes high in potassium, but they also contain a good amount of calcium. This is a common liming material for correcting acidity. But it can be confusing to know the correct type of ashes to use and how to use them.

As a general rule, you might be better off composting ashes than adding them to the soil.

There are a couple of reasons for this.

The soluble salts contained in ashes are possibly harmful to some plants. When you put ashes into compost, these salts are slowly washed away. Heavy rainfall and watering encourage the salts to leach out.

Ashes are also very alkaline. So adding them to soil lowers acidity levels. This is good if you know your soil is overly acidic, but avoid overdoing things. However, compost is quite acidic, especially in the early stages of decomposition. So adding ashes can therefore help balance pH levels in your compost.

One crucial thing to keep in mind is where do your ashes come from?

There are a few situations where you don’t want to use ashes at all…

Can I compost charcoal ashes? 

The term “charcoal” refers to the manmade type of coal made from burning wood. Ash produced from charcoal results in the correct type of ashes for adding to compost.

It’s essential to understand the type of ashes you use for composting.

The powdery residue that remains after a wood fire in stoves and fireplaces is good to compost.  

Keep in mind that the type of wood you burn slightly impacts the level of beneficial potassium contained in the ashes. For example, young wood will result in higher potassium levels than old-aged wood.

You should also make sure the wood used in the fire is not treated wood. Chemically treated timber could leave trace residues which might be harmful if put in compost.

Can you put coal ashes in compost?

Natural coal is a mined mineral that includes heavy metals, chemicals, and sulfur traces. These substances are potentially toxic for plants. So ashes from mined raw coal should not be composted.

As you can see, it’s helpful to understand the source of your ashes if you want to avoid adverse effects on your compost biology and plant health.

Can I compost fireplace ashes? 

Fireplace ashes can be composted if the fuel used in the fire is wood. Do not use fireplace ashes if you use natural coal or artificial firelogs. Also, avoid ashes from burnt, treated timber.

Fireplace ashes generally refer to the powdery substance remaining after a wood fire. This is safe to use if you know the wood is from a natural, untreated source. If the wood was painted or stained, then avoid using the ashes.

Can I put wood ashes in compost? 

Wood ashes are safe to use in compost. This is the best type of ash to add to a compost bin. Wood from young trees will give you the best potassium content

Can I compost paper ashes? 

Paper is generally made from wood pulp and contains cellulose. Some paper uses cotton, but both these materials are organic and can be safely used after burning. 

Remember that the paper-making process reduces the amount of beneficial nutrients in the paper, adding less goodness to your compost heap.

Can you compost ash from BBQ?

Avoid using ashes leftover from a barbecue. It can be contaminated with fats from cooked meat. Also, if the barbecue was started with chemical firelighters, the ashes could be contaminated with harmful chemicals.

Even if you used natural wood charcoal as fuel for your barbecue, the resulting ashes could still end up with contaminants. If you add these to compost, they will harm composting microbes.

Is ash brown or green compost

Ash is relatively high in carbon. This makes it a brown composting material. The calcium carbonate content of ashes also makes it strongly alkaline, so you need to be aware of its effect on your compost heap.

The C: N ratio of ashes is 25:1. In other words, it is 25% organic carbon. 

Thanks to the calcium carbonate content, it is more alkaline in nature. 

Do ashes make compost acidic or alkaline? 

Wood ashes are alkaline in nature. Ashes have a liming effect which means they help neutralize acidity. When added to compost, they make it more alkaline.

Wood ash is very alkaline, with a pH level between 9 and 11. Adding them to compost helps neutralize acidity levels. Adding them to fresh composting materials makes sense because compost usually starts out on the acidic side. 

Remember that pH measures the acidity or alkalinity of a substance. A pH of around 7 is considered neutral.

The resulting ash compost can be good for very acidic soils. Use it as mulch around lime-loving plants. But avoid using it on acid-loving fruit bushes like blueberries or raspberries and flowering plants like rhododendrons.

The most important plant nutrients are most readily available in somewhat neutral soil (pH of 7). However, some micronutrients become more freely available when the soil is slightly acidic (pH between 5,5 and 6).

Adding ash compost to soil can be an excellent way to achieve an optimal pH range for plants between 6.2 and 7.3

It’s always a good idea to test your soil pH beforehand so you know the starting point of your soil.  

A soil test kit like this one (Amazon) gives quick results, but if you want a more lasting solution, you can get some excellent pH and moisture meters like this one.

How to compost ashes

Add small amounts of ash to your compost heap. As a general rule, sprinkle a thin layer of ash every 12 to 18 inches of organic matter. Avoid using too much ash at a time because of its high alkalinity. 

You should try to remove any large unconsumed pieces of wood using a garden sieve – here’s an example on Amazon. 

How much ash should I put in my compost?

You only need to add a thin layer of wood ash for every foot or so of organic materials. 

Some nutrients can get washed out if your compost isn’t covered and gets soaked by rainwater. This includes the unwanted salts, but also some of the beneficial potassium. To counteract this, it’s a good idea to add several layers of ash as you build up your compost heap.

Can you put too much ash in compost?

It is possible to use too much ash when composting, so avoid excessive ash doses. Considering the high alkalinity of ash, you should limit the amount of wood ash to thin layers. 

Too much potash can unbalance the pH levels of compost. Composting microbes and fungi work most efficiently at a neutral range of pH values. 

Avoid adding large amounts of ash, especially to more mature compost, which is already more alkaline than fresh compost.

Features and secrets of feeding plants with wood ash

Wood ash as waste in rural areas often accumulates in enormous quantities. At the same time, knowledgeable summer residents find it quite reasonable to use it as a natural fertilizer for feeding various plants. The high content of potassium, magnesium and calcium in the ash really motivate such use, however, this growth stimulation option may not always be appropriate. There are certain nuances that must be considered when using such a natural fertilizer. nine0004

Photo: foodbay.com

Particularly interesting in the list of constituents of potassium, because it has a decisive effect in improving the flowering and fruiting of a number of horticultural crops. It is for this reason that the use of wood ash as a fertilizer seems to be one of the best options when perennials begin to gradually reduce their yield. There are even some informative facts about wood ash that will tell you which version of it is best to give preference to:

  • Ash from young trees has a greater amount of useful micro- and macroelements compared to old wood.
  • Coniferous trees have fewer nutrients than hardwoods, especially hardwoods.
  • If the wood has been chemically treated, top dressing with wood ash of this type of any plant is strictly not recommended.

However, in combination with other types of natural fertilizers, ash gives very interesting results, which makes its applications even more extensive. nine0005

Wood ash + compost

The composition of the ash is close to alkalis, therefore, in combination with natural organic compost, it helps to stabilize the acid balance of the latter. Due to this, the worms can more efficiently process the organic matter present in the compost, thereby accelerating the process of its transformation into a full-fledged fertilizer of natural origin. What's more, the alkalinity can even restore overly acidic soil if periodically sprinkled with a thin layer of ash. nine0005

This option of using wood ash for the garden has been practiced for many centuries, and the effectiveness of the technique does not raise even the slightest doubt. If we approach this issue from a scientific point of view, it has long been established that for most vegetables, soil acidity at a pH level of 6.5-7 is considered optimal. If this indicator is lower, then the excess acid must be neutralized with alkali - this is precisely the problem that ash solves. Also, such a combination is appropriate in cases where cattle manure is used as the main fertilizer to accelerate plant growth - it is characterized by high acidity, therefore, it can be most effective only after neutralization with natural alkali. nine0005

For maximum efficiency, it is essential to understand how to use wood ash to neutralize excessive acidity in the compost. It is worth adding it in small quantities, but often enough - layer-by-layer spraying every 15 cm of compost heap growth would be ideal. In this case, the resulting mixture will be as uniform as possible and the acid neutralization process will take place in the shortest possible time.

Interesting fact: wood ash is about twice as effective at neutralizing acid as lime, which is traditionally used in such situations. nine0005 Photo: ©aixklusiv / pixabay.com

Use of wood ash in garden beds

Pure wood ash can be used not only for composting, but also directly on the rows. The generally accepted standard is about 50-70 grams of product per 1 square meter of area. This will be especially effective in cases where the soil is highly acidic. The benefits of wood ash in this case will be as obvious as possible in the shortest possible time after the start of its use. The processing of cabbage deserves special attention, since it is this crop that often suffers from the keel disease, which manifests itself in the case of increased soil acidity. nine0005

Despite these difficulties, the general average picture was established several centuries ago by the great scientist D.I. Mendeleev. According to his analysis, chemical compounds such as calcium silicate and carbonate, sodium orthophosphate, potassium orthophosphate and other calcium-based compounds are considered “leaders” in composition.

Such a multifaceted set of chemical components gives an extremely diverse result - improving crop growth, protecting against various diseases and even preventing possible parasites. That is why wood ash for plants is used to this day, due to its effectiveness and versatility of use. nine0005

Possible contraindications

Since wood ash deacidifies the soil, there is an opinion that it must be used almost annually to achieve the desired result. In practice, everything is far from being so simple, since there are often cases when the soil has a normal level of acidity and its decrease can cause a negative result instead of the expected increase in yield.

There are quite a few options for feeding plants with wood ash, but some techniques are considered traditional and are used everywhere. As a prophylactic, ash can be used before the onset of winter in those places where it is planned to plant especially violently growing crops. The second option is to sprinkle the earth directly around the plants during their active growth. nine0005

Ash also shows a good effect in relation to tomatoes, which are particularly acutely deficient in calcium - this element is found in large quantities in burnt wood. Berry crops, including gooseberries, currants and other bushy plants of this type, can also be attributed to this category. It is precisely those elements that are contained in wood ash that will allow you to get a much larger harvest and at the same time generally improve the well-being of the bushes.

A little about the composition

It is practically impossible to determine the chemical composition and bring the obtained data to a single value. This is due to a number of factors at once:

  • the age of the trees;
  • wood type;
  • growth conditions;
  • general soil composition.

Each of these factors directly affects what set of chemical elements will remain in the ashes after the complete combustion of wood.

What else do you need wood ash for? nine0004 It can be used as a liquid fertilizer, since such a liquid contains an impressive amount of useful minerals. This is especially true in the case of soaking the seeds before planting - this significantly speeds up the process of their germination. Another use is that wood ash can be added to clay soils to soften them and prevent hard clods from forming after moisture enters the soil.

Which plants do not like wood ash

Despite all its positive properties and minimal contraindications, there are cases when it is still better to refuse burnt wood. Due to the presence of an alkaline effect, ash is unacceptable for processing those areas of land where plants predisposed to increased soil acidity live. Blueberries and raspberries are among the most obvious of these options, although the latter does not react as badly to reduced acidity.

Also, the option of feeding plants with wood ash is unacceptable in the case of potatoes, since the result can be strictly negative. The fact is that in this case, the risk of potato scab increases many times, and this entails crop loss and other negative consequences. nine0005

The most important recommendation is to use ashes without fanaticism, especially if the exact level of soil acidity is not known. Excessive introduction of such material into the soil can significantly reduce acidity, up to the deterioration of the general condition of arable land. That is why, before using such a natural fertilizer, it is better to independently determine the level of acidity using litmus paper, distilled water and a soil sample.

The whole procedure takes a minimum amount of time and is quite real even at home. To verify the results, it is enough to familiarize yourself with the color table of acidity, which will clearly demonstrate the overall level of oxidation. nine0005

Source:
highly specialized food industry portal
Foodbay

Imagine that you get a fertility product for your garden from time to time. And at the same time, you can significantly save on garbage disposal and the purchase of potash fertilizers! For example, wood ash contains in small quantities almost all the elements necessary for the plant, except for nitrogen. For those who do not have a stove, there is also a way out, since high-quality wood ash can be bought at almost any garden store. nine0005

Mix with compost heap

Due to the fact that wood ash easily transfers its nutrients to water, it is not advisable to keep it outdoors - rain will easily wash away the fragile structure. It is advisable to spread the ashes in a covered compost heap or scatter over dug up beds. When adding ashes to the compost heap, it will be useful to make some layering, i.e. alternating layers of ash and plant residues. Thanks to the ash, the compost will lose a significant amount of acidity, which means it will become a real bait for colonizing beneficial microorganisms, earthworms. nine0005

Coal ash

In some countries, in addition to wood heating, there is heating with coal. The principle of its operation is the same, however, the mass obtained after burning is somewhat different from wood. The composition of coal ash contains little potassium, calcium and phosphorus, which is why it is a waste of time to use it as a fertilizer for garden plants. Experts advise considering coal ash as an option for ennobling wet clay soils. It contains approximately 40-60% of silicon oxides, due to which it noticeably loosens and drains lands previously unsuitable for growing crops. nine0110 Another interesting property of coal ash is its ability to significantly acidify soils after heavy application. Sulfur in its composition gradually forms sulfates, which can displace carbonates in saline soils and provoke the formation of soluble salts, which are quite easily washed out of the soil by moisture. Those. this ash is completely unsuitable for acidic and sandy soils, but will perfectly cope with the alkaline environment in highly saline soils.

We use coal ash

When coal ash is mixed with calcium nitrate, cattle manure, ammonium carbonate and bicarbonate, bird droppings, it can be applied to neutral and slightly acidic lands. However, with this method, the nitrogen content in it can be significantly lost. Usually they take up to 3-3.5 kg for each hundred acres of the plot, the mixture is applied in late autumn.
Garlic, onion, rutabaga, horseradish, cabbage, mustard, radish will be grateful for the use of pure ash, since these plant crops absolutely need at least a minimum sulfur content in the soil for full growth. nine0005

We use wood ash

Wood ash is often used in horticultural areas as a fertilizer for acidic or neutral soils. Due to the absence of the element chlorine in its composition, ash can be used for plants that are extremely sensitive to chlorine, such as currants, garden strawberries, potatoes and raspberries. Wood ash has a beneficial effect on many varieties of cabbage, protecting them from the destructive black leg and keel. Patissons, zucchini, cucumbers and sweet peppers also love ash-treated soil. nine0110 Wood ash can be added to the holes when planting seedlings in a permanent place of growth (1-3 tablespoons in each hole). When planting seedlings of plums, cherries, currants, you can add 2 tbsp. spoons of ash in dry or dissolved form. For subsequent feeding of young seedlings (not more often than 1 time in 3-4 years), the near-stem annular grooves are watered with a bucket of water with two glasses of ash. Mature trees fertilize 1.5-2 kg of ash.
For fertilizing tomatoes, cucumbers, cabbage and other vegetable crops, use an ash solution at the rate of 100-200 g per bucket of water. Fertilizer is poured, stirring constantly, into pre-prepared grooves, which are then sprinkled with earth. One plant usually takes 2 cups of the solution. nine0110 As regards the time of application of ash in the garden, for heavy, poorly fertile soils, digging in the fall is recommended, and for airy sandy loamy soils, spring is an excellent time for application. It has been noticed that the ash solution not only alkalizes the soil, but also significantly increases the viability of plants, especially those that were planted from home seedlings.

Ash composition

The best and most valuable ash in terms of nutrient content is the ash obtained after burning grass, buckwheat and sunflower are especially preferred. Useful for burning and fallen leaves of trees: so in the leaves of birch, when burned, a huge amount of easily digestible potassium is preserved. The poorest content of phosphorus and potassium is peat ash, of course it can be used, but perhaps as a source of calcium for plants. nine0110 The use of ash allows plants to easily absorb phosphorus from the soil, in terms of its qualities it can outperform even superphosphate, which is so beloved by all summer residents.
For the best ash fertilizer effect, you can use straw and wood ash mixed with humus (or peat) in a ratio of 1 to 4. Thus, it will be easier for you to distribute top dressing among the beds, and it will be easier for plant crops to absorb all the valuable nutrients from the soil.

In pest control

Tree and grass ash can easily deal with a problem in the area such as strawberry gray mold. For treatment and prevention, it is necessary to pollinate strawberries with ash, with a consumption of approximately 10-15 g per plant. The procedure can be carried out 1-3 more times, reducing the ash consumption to 6-7 g.
Many plant health problems caused by the action of bacteria, fungi, viruses and insects easily disappear after repeated spraying of crops with ash suspension.

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