Home » Misc » Using ash in compost

Using 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.

We link to vendors to help you find relevant products. If you buy from one of our links, we may earn a commission.

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.

Wood ash

Ash from our stoves and barbecues can serve a person more than once. 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. nine0003

Mixed 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. nine0003

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. nine0015 Another interesting property of coal ash is its ability to significantly acidify the soil 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. nine0003

We use wood ash

Wood ash is often used in gardens 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. nine0015 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.
To fertilize 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. nine0015 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. nine0015 The use of ash allows plants to easily absorb phosphorus from the soil, in terms of its qualities it can give odds even to 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

Woody and herbaceous crop ash can easily deal with an area problem 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 consumption of ash 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. For its preparation, ash well sifted through a fine sieve is used, which is subsequently boiled for 30 minutes over medium heat. The resulting solution is diluted with 10 liters of water and 40 grams of laundry soap. A solution of wood ash is sprayed in the morning in dry calm weather. As a preventive measure, you can spray every 2-3 weeks. nine0003

Wood ash is an excellent natural material that can give new strength and fertility to all plants in your area. Let new recipes from nature itself become your faithful companion and assistant in the fight for rich harvests!

Ash and compost | Country ideas and experience of gardeners

Ash

There is no nitrogen in it, but there are up to thirty second different elements. These are elements such as: potassium, calcium, magnesium, iron, silicon, phosphorus, sulfur, boron, manganese and without that later. Phosphorus from ash is absorbed by plants better than that contained in superphosphate. It does not contain chlorine, to which raspberries, currants, strawberries, and potatoes do not respond well. nine0003

As we know, 70 grams of ash applied per square meter of sandy, sandy loamy and podzolic lands fully satisfies the needs of most plants in boron, respectively, it is extremely useful for tomatoes and cabbage.

Ash strengthens the structure of the earth, creates favorable conditions for the development of microflora, especially nitrogen-fixing bacteria that improve the nitrogen nutrition of plants. The impact of this fertilizer is recorded for four years after the end of its application to the land. nine0003

Heavy and podzolic soils respond best to ash: as a lime fertilizer, it reduces acidity - in the ashes of firewood, lime is not uncommon up to 40%.

Burnt potato leaves contain more than 20% potassium, 8% lime and 32% phosphorus. Based on this, at the end of the harvest, it is necessary to rake the tops and burn it right there on the site. This ash is good not only for potatoes, but also for beets and carrots: in autumn or spring, up to 700 grams of ash is plowed per square meter of poor land. nine0003

For peas, 150-200 grams are needed, and for fruit trees - 100-150 grams per 1 sq. meter.

The complex of macro- and microelements of ash has an excellent effect on strawberries after trimming the whiskers, on potatoes - when loosening row spacings. For this, both dry ash and an aqueous solution are used, which are prepared before consumption (50-150 g per bucket of water). When feeding, the liquid is always mixed in order to evenly distribute the hard residue containing phosphorus between the plants.

Cabbage, cucumbers, tomatoes are treated with this solution at the rate of 0.5 liters per plant.

It is not advised to add ash to liquid organic nitrogen-containing top dressings (slurry, liquid composts), because nitrogen is lost as a result. There is no need to mix it with phosphorus preparations (superphosphate, etc.) - plants absorb it worse. It is possible to mix ash with other mineral fertilizers, but only before applying it to the ground.

It is forbidden to apply ashes together with lime, as well as to lands that have been limed relatively recently, so as not to increase their alkaline reaction. nine0003

Ash mixed with compost soil is good: it activates the decomposition of organic matter and enriches the compost with microelements.

If you bring ashes into the ground, try to cover it to a depth of 8-10 centimeters. On the surface, it forms a crust that prevents the earth from breathing.

Loamy and clay soils can be treated with ash in spring and autumn, mixing it with sand, sandy soil - in spring, 100-200 g per square meter.

If you mix one part of the ash with two parts of perfectly rotted wet peat or humus, then the fertilizer will not burn the roots of plants or tubers. nine0003

In most cases, a large amount of ash accumulates in the household, and care must be taken that it does not get wet - otherwise potassium, one of its most important components, is lost.

Ash is quite often used as a means of protecting plants, for example, they pollinate strawberries against gray rot, viburnum and other shrubs, especially those suffering from negative insects. When plants are affected by powdery mildew, they are sprayed with ash liquor. It is prepared like this: 300 g of sifted ash is boiled for half an hour, insisted for about an hour, filtered and topped up with water up to 10 liters. nine0003

In order for the lye to adhere better, add 40 g of planed soap to it. Sprayed in quiet clear weather, at a time when rain is not expected. Such processing can be carried out once every fifteen days.

Lye, by the way, repels insects from vegetable sprouts.

If birch wood ash is added under the potatoes, the tubers grow better, they contain more starch, and the plants suffer less from late blight. Cabbage fertilized with ash is less likely to get sick with clubroot, and beets - with tail rot and heart rot. nine0003

We are sure that larvae of the Colorado potato beetle and some adult insects die on potato plants pollinated by ash.

Ash is also used as an antiseptic: it is powdered on sections of flower bulbs, tubers of peonies, dahlias, irises and potatoes, while planting it with parts of tubers.

If a pumpkin has a bed sore, the affected area is cut out and sprinkled with ashes.

Compost

On a small household plot, the land is soon depleted. Some agronomists are sure that compost is only slightly inferior in treasure to manure. When thirsty, compost can provide vegetable gardens and the garden's organic needs for the whole season. nine0003

You just need to remember a couple of important things.

Layers of waste in the compost heap should alternate with earth, sawdust or peat. It is possible to pour them with ash, superphosphate (trying not to mix the last two substances in one layer), moisten them with slurry. The compost heap must necessarily be closed from the sides and be above the ground with the turf removed, otherwise various microflora and earthworms from the ground will not be able to get into it, which improves the aeration of the compost. nine0003

Make the top of the pile in the form of a trough so that the water does not drain, but evenly wets it. He put on land with a compost heap, without fail warm and semi-shaded, it is possible to plant beautifully flowering annuals, for example, sunflowers or Jerusalem artichoke.

Don't be upset if the heap is not completely rotted: fresh compost that has been stored for 6-9 months has more microorganisms than compost that has been stored for more than a year. Such compost will be assimilated soon, especially if the pile is dug up twice a season. nine0003

Today gardeners and gardeners often use the so-called wet composts. They cook them in huge barrels. Weeds torn off during weeding (before flowering!), Cut tops, leaves and other non-lignified waste must be put in a barrel (approximately one third of its quantity), flooded, covered with foil and placed in an open, perfectly warmed by the sun place.

Approximately 14 days later, when the contents ferment and a peculiar smell reminiscent of manure appears, garden trees and a vegetable garden are watered with liquid. Many gardeners dilute such a concentrated infusion with four to five amounts of water. At the end of the next weeding of the beds, the newly collected weeds are placed in a barrel, filled with water, and the fermentation process is resumed. nine0003

The remains from the bottom of the barrel are thrown into the compost heap.

benefit and Ash harvesting. Part 1.

Fascinating notes:
Selected by important queries, relevant articles: