09-19-2019, 12:47 AM
Wood ash can be very good when applied to soil. But there are many precautions you'll have to take to prevent bad consequencies. It work best in soil that are acidic. When wood is burnt, about 0.43 to 1.82 percent of the mass of wood (dry basis) results in wood ash. Ash contains about 25 to 45% calcium carbonate, less than 10% potash , and less than 1% phosphate. There are trace elements of iron, boron, manganese, zinc, copper etc and some heavy metals.
Uses of Wood Ash
1. As an alternative to lime to increase soil pH. Unlike lime, it also add nuyrients to the soil.
2. In organic hydroponic solutions, it can be used to replace inorganic compounds containing calcium, potassium, magnesium and phosphorus.
3. It can added to composts. Its high char content will help control odor.
4. As fertilizer. Although ash has low NPK value (0-1-3), it contains a lot of macro and micro nutrients that are essential for plant growth. As a result, when ash is used in place of agric lime, it can increase plant growth up to 45 percent over traditional limestone [1]. This is particularly true if the soil is lacking in some nutrients.
Wood ash has high pH (8-13) because of its high calcium carbonate (CaCO3) content (25-45%). Just like agricultural lime, it can be used to increase soil pH to desired level (different crops have different desired pH ranges). Wood ash has a liming effect of between 8 and 90 percent of the total neutralizing power of agric lime. Below are reasons why you should not apply too much ash to your farm.
1. High Soil pH: Wood ash increase soil pH. If soil pH exceed desired level, crops will not grow well because they no longer have access to certain essential minerals like phosphorus, iron, boron, manganese, copper, zinc and potassium. This will definitely lead to financial loss.
2. Ash contains some heavy metals like cadmium, nickel and chromium. Plants will absorb these metals and store them in their tissues. When human and animals eat these plants, their health will be endangered.
3. Soil Salinity: Wood ash is also rich in potassium ..... Excessive amount of these salts in the soil is bad for plant health.
How to Apply Wood Ash Correctly
To be on the safe side and avoid over application with its bad effects, you will need the service of a soil laboratory before you apply ash in your farm. The amount of ash that you can apply varies by field. It depends on calcium carbonate equivalent (CCEs), potassium content of soil and soil pH. The laboratory will conduct the following tests:
1. Soil Test: To determine pH and nutrient levels in the soil. With this knowledge, you can apply the right quantity of ash to attain desired pH and because ash already contain some nutrients, you'll avoid over application of nutrients when using chemical fertilizers.
2. Ash nutrient analysis: This is important because the nutrient content of ash from different sources varies widely. The test determines the calcium carbonate equivalent (CCE) of the ash and its nutrient content, including amount of heavy metals present. Ash with high amount of heavy metals should be avoided, but this is rare.
About CCE: The calcium carbonate equivalent (CCE) of ash measures its liming ability. The CCE tells you how well the wood ash will raise the soil pH compared to lime (calcium carbonate). CCE varies widely (25-60%) from ash to ash, making lab testing very neccessary. With proper soil tests and the CCE of the wood ash, application rates for wood ash can be calculated by dividing the recommended lime application rate by the CCE of the wood ash. E.g. if 3 tons of lime are needed per acre and the ash has a CCE of 50%, then ash application
rate (tons/acre) is 3/50 x 100 = 6 tons of ash per acre would be required to raise the pH to the desired level. If you'll be applying chemical fertilizer, knowing the nutrient content of the ash will help you to avoid over application of nutrients already present in the ash.
Applying Ash
Ash can be spread by hand or mechanically with a conventional manure spreader or lime application equipment. It can be top dressed or incorporated into the soil. To get the full benefit, incorporate the wood ash throughout the root zone because the benefits only occur where the ash and soil are in contact.
Do not apply ash immediately before planting or during early emergence because when newly applied, soil pH may be in the alkaline range and this could affect normal plant growth.
Ash is dry and dusty. It will irritate skin and eyes and can cause respiratory problem when inhaled. Protect your skin, nose and eyes with gloves, long-sleeve shirt, nose mask and safety glasses when applying ash.
Do not combine ash with fertilizers like ammonium sulfate, urea, ammonium nitrate to prevent loss of nitrogen in the form of ammonia gas.
Conclusion
The bad effect some farmers experienced when they apply ash is mainly due to high soil pH resulting from over application of ash. If you can apply ash in such a way as to maintain the proper soil pH range (depending on the crop you are growing), you'll always get good result when compared to lime application.
Ref
1. https://extension.uga.edu/publications/d...0Amendment
2. https://extension.umaine.edu/publications/2279e/
Uses of Wood Ash
1. As an alternative to lime to increase soil pH. Unlike lime, it also add nuyrients to the soil.
2. In organic hydroponic solutions, it can be used to replace inorganic compounds containing calcium, potassium, magnesium and phosphorus.
3. It can added to composts. Its high char content will help control odor.
4. As fertilizer. Although ash has low NPK value (0-1-3), it contains a lot of macro and micro nutrients that are essential for plant growth. As a result, when ash is used in place of agric lime, it can increase plant growth up to 45 percent over traditional limestone [1]. This is particularly true if the soil is lacking in some nutrients.
Wood ash has high pH (8-13) because of its high calcium carbonate (CaCO3) content (25-45%). Just like agricultural lime, it can be used to increase soil pH to desired level (different crops have different desired pH ranges). Wood ash has a liming effect of between 8 and 90 percent of the total neutralizing power of agric lime. Below are reasons why you should not apply too much ash to your farm.
1. High Soil pH: Wood ash increase soil pH. If soil pH exceed desired level, crops will not grow well because they no longer have access to certain essential minerals like phosphorus, iron, boron, manganese, copper, zinc and potassium. This will definitely lead to financial loss.
2. Ash contains some heavy metals like cadmium, nickel and chromium. Plants will absorb these metals and store them in their tissues. When human and animals eat these plants, their health will be endangered.
3. Soil Salinity: Wood ash is also rich in potassium ..... Excessive amount of these salts in the soil is bad for plant health.
How to Apply Wood Ash Correctly
To be on the safe side and avoid over application with its bad effects, you will need the service of a soil laboratory before you apply ash in your farm. The amount of ash that you can apply varies by field. It depends on calcium carbonate equivalent (CCEs), potassium content of soil and soil pH. The laboratory will conduct the following tests:
1. Soil Test: To determine pH and nutrient levels in the soil. With this knowledge, you can apply the right quantity of ash to attain desired pH and because ash already contain some nutrients, you'll avoid over application of nutrients when using chemical fertilizers.
2. Ash nutrient analysis: This is important because the nutrient content of ash from different sources varies widely. The test determines the calcium carbonate equivalent (CCE) of the ash and its nutrient content, including amount of heavy metals present. Ash with high amount of heavy metals should be avoided, but this is rare.
About CCE: The calcium carbonate equivalent (CCE) of ash measures its liming ability. The CCE tells you how well the wood ash will raise the soil pH compared to lime (calcium carbonate). CCE varies widely (25-60%) from ash to ash, making lab testing very neccessary. With proper soil tests and the CCE of the wood ash, application rates for wood ash can be calculated by dividing the recommended lime application rate by the CCE of the wood ash. E.g. if 3 tons of lime are needed per acre and the ash has a CCE of 50%, then ash application
rate (tons/acre) is 3/50 x 100 = 6 tons of ash per acre would be required to raise the pH to the desired level. If you'll be applying chemical fertilizer, knowing the nutrient content of the ash will help you to avoid over application of nutrients already present in the ash.
Applying Ash
Ash can be spread by hand or mechanically with a conventional manure spreader or lime application equipment. It can be top dressed or incorporated into the soil. To get the full benefit, incorporate the wood ash throughout the root zone because the benefits only occur where the ash and soil are in contact.
Do not apply ash immediately before planting or during early emergence because when newly applied, soil pH may be in the alkaline range and this could affect normal plant growth.
Ash is dry and dusty. It will irritate skin and eyes and can cause respiratory problem when inhaled. Protect your skin, nose and eyes with gloves, long-sleeve shirt, nose mask and safety glasses when applying ash.
Do not combine ash with fertilizers like ammonium sulfate, urea, ammonium nitrate to prevent loss of nitrogen in the form of ammonia gas.
Conclusion
The bad effect some farmers experienced when they apply ash is mainly due to high soil pH resulting from over application of ash. If you can apply ash in such a way as to maintain the proper soil pH range (depending on the crop you are growing), you'll always get good result when compared to lime application.
Ref
1. https://extension.uga.edu/publications/d...0Amendment
2. https://extension.umaine.edu/publications/2279e/
