What Is Wood Ash And How Can I Use It In Compost?
Wood ash is a type of organic material made from trees such as oak, maple or birch. It consists mainly of cellulose (a form of plant cell wall) and lignin (an oily substance). Both are biodegradable materials that break down into harmless carbon dioxide gas when burned. They are also used in the manufacture of paper, furniture and other products.
The ash is usually mixed with water and added to soil. When it is burnt, the ash releases oxygen and helps decompose organic matter in the soil. It also acts as a fertilizer. Soil tests have shown that wood ash increases fertility by up to 30%.
It is not known if burning wood ashes will increase crop yields but they may help reduce erosion, improve drainage and provide nutrients for beneficial microorganisms in the soil.
How Much Should I Add To My Compost?
It depends on your climate and local conditions. If you live in a hot area, then adding too much ash could cause problems because it would raise the temperature too high. However, if you live in a cold region where there is little sunlight, then using wood ashes might be useful. Some studies have shown that burning wood ashes improves soil quality and reduces erosion in areas where they are used.
The ashes also contain beneficial nutrients such as potassium, magnesium, calcium and other trace elements. It is one of the few natural sources of potash (a form of potassium) that is free and easy to get. Dissolved in water ash can even be used to water plants but it shouldn’t be used on aquatic plants or those that have a high sensitivity to sodium.
The ash can also contain traces of heavy metals but they are generally at low levels. Any type of ash is best used on soil that has been previously tested to make sure the levels are acceptable. If the levels of heavy metals are too high, then the ash can be used as an amendment to raise the soil pH level instead.
What Other Types Of Ash Can I Use?
Any organic matter that is burned can be used as a soil amendment. Here is a brief list:
Wood ash. As discussed above, it is a good source of potash and other trace elements.
Cotton husk ash. This is a by-product of harvesting cotton.
Hair ash. This is made from the used hair in barber shops and beauty salons. It can be mixed with wood ash to help it decompose faster.
Sawdust ash. This is sometimes added to wood ash to help it break down.
Sugar cane ash. This is the by-product of sugar cane processing. It is sometimes mixed with other types of ash to make them easier to use.
Manure ash. This by-product of farming has similar properties to wood ash and it can come from cattle, sheep, goats, horses or other animals.
Seaweed ash. This is a type of ash that can be dried and mixed with other types of ash to make them more effective. It also provides a slow release of nutrients over time.
Poultry manure ash. This is a mixture of chicken, turkey or other bird manure that has been composted. It can be added directly to garden soil but if it is dry, it should be moistened first.
While ash from most organic materials can be mixed with soil, you should avoid using ash from any plants that have been treated with pesticides or herbicides. The chemicals could remain in the ash and damage your plants. It is also a good idea to avoid using ash from diseased plants in your garden.
There are many other types of ash that can be used in the garden or for other purposes around the home. Many of these “ashes” are considered to have negative effects when they are burnt but using them on soil seems to have positive effects. Just check the ingredients to make sure they are not from any noxious plants or treated material before you add them to your garden.
Pine needles, for example, have high acid levels and can damage plants if they are used as a mulch. But they can be mixed in the soil, with wood ash or other ingredients to make a good growing medium. They are also a good source of potash.
Some animal manures have high salt content. This can be good for soil in small amounts but too much can burn your plants. They are also a good way to add potash and other nutrients to the soil.
Seaweed, of course, is a rich source of potassium and other minerals. But it also has a high salt content and should be used only in small amounts or mixed with other ingredients.
Egg shells are another material that can be used as an amendment to the soil. They are good for breaking down slowly and releasing calcium and other nutrients to the soil. But they shouldn’t be used in large amounts because they can make the soil too alkaline.
Other animal based products, such as blood, bones, feathers, fur and other parts that are removed during the butchering or processing of animals can also be used. They make a good slow release source of nutrients for your soil. But they are more often mixed with other ingredients to make sure that they have balanced levels of the elements that they contain.
Bone meal is a popular organic based fertilizer. It can be made from the bones of mammals, birds or fish. It is slow releasing and tends to be on the acidic side. It should not be used in large amounts or it could damage your soil ecosystem.
Fish emulsion is made from, as you might expect, fish. It is rich in potash and nitrogen and makes a good natural fertilizer but it can also damage soil organisms if overused.
There are many other organic based fertilizers. Some are specially made for specific types of plants. If you are using organic based plant food, follow the directions carefully and only use what is required. Too much of even “natural” plant food can burn your plants.
When planting trees, shrubs and flowers make sure that the plants you choose will thrive in your specific climate, soil type and available light conditions.
And have fun! Gardening, when you have the time, is a great stress reliever.
Sources & references used in this article:
Determination of fungal succession during municipal solid waste composting using a cloning‐based analysis by J Hultman, T Vasara, P Partanen… – Journal of Applied …, 2010 – Wiley Online Library
Reducing nitrogen loss during poultry litter composting using biochar by C Steiner, KC Das, N Melear… – Journal of environmental …, 2010 – Wiley Online Library
Control of Hymenoscyphus fraxineus, the causal agent of ash dieback, using composting by R Noble, JW Woodhall… – Forest …, 2019 – Wiley Online Library
Tropical soils degraded by slash‐and‐burn cultivation can be recultivated when amended with ashes and compost by JM Gay‐des‐Combes, C Sanz Carrillo… – Ecology and …, 2017 – Wiley Online Library
Metal bioavailability and speciation in a wetland tailings repository amended with biosolids compost, wood ash, and sulfate by PS DeVolder, SL Brown, D Hesterberg… – Journal of …, 2003 – Wiley Online Library
Investigation of compost× fertilizer interactions in sweet potato grown on volcanic ash soils in the highlands of Papua New Guinea. by SR Preston – Tropical Agriculture, 1990 – cabdirect.org
… of fertilization with anaerobic, composted and pelletized sewage sludge on soil, tree growth, pasture production and biodiversity in a silvopastoral system under ash … by AA Rigueiro‐Rodríguez… – Grass and Forage …, 2010 – Wiley Online Library