TINA'S
Southern CHICKENS
USING WOOD ASHES AS AN AMMENDMENT
What is in wood ashes?
• Wood ashes are composed of many major and minor elements needed by the tree for plant growth (see Table 1 below for details). Most of these elements are extracted from the soil and atmosphere during the tree's growth cycle. Therefore, they are elements that are common in our environment and are also essential elements in the production of crops and forages.
• Wood ashes are a good source of many micronutrients that are needed in trace amounts for adequate plant growth. The most abundant of these is calcium, which gives the ash properties that are similar to agricultural lime. They are also a good source of potassium, phosphorus, magnesium, and aluminum.
• Wood ash would probably be about 0-1-3 (N-P-K) if put into commercial fertilizer terminology.
• Wood ashes contain few elements that pose environmental problems. Heavy metal concentrations are typically low and not in a highly extractable or available form.
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Should I put wood ashes in my patch?​
• It is important to get a soil test before deciding to put wood ashes in your patch.
• Wood ashes raise the soil pH.
Caution: If your soil pH is 7.5 or higher you do not want to use any wood ashes in your soil.
• If your soil pH is below pH 7.0 wood ashes are an alternative to using ground limestone.
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How do wood ashes affect pH?
• Wood ashes raise the pH (alkalinity) of the soil in much the same way as limestone. However, unlike limestone, which can take six months or more to change soil pH, wood is highly water soluble and changes the soil pH very rapidly.
​Caution: This can cause problems, as a soil pH over the optimum level can affect plants adversely.
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How do wood ashes compare to limestone?
​• Lime is made by finely grinding up chunks of limestone which is about 98% calcium carbonate.
• Ground limestone does not dissolve readily in water while wood ashes are very soluble in water.
Note: 80-90% of the ingredients in wood ashes will dissolve in water.
• Wood ash application is similar to lime application. Both materials can benefit crop productivity but wood ash has an added advantage of supplying additional nutrients.
​Caution: Both materials are also alkaline and could cause crop damage if over applied or misused.
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How much wood ash should I add?
​• It is important to first get a recommendation for limestone from a reputable lab (soil test). ​
• The general consensus is that two pounds of wood ashes equal one pound of ground limestone in regulating soil pH. In other words it takes twice as much ash as lime to affect same change in pH.
• Recommendations are that you should limit the application of ashes to 2-5 pounds per 100 square feet of soil per year. This is to avoid problems of excess salinity, alkalinity, and plant nutrient availability.
​Caution: If you add too much wood ash, you can drastically alter the pH and cause nutrient imbalances.
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When should wood ashes be added to my patch?
• The best time to apply wood ashes is in the fall or winter. This is because soil pH is generally lower during this time and applications will allow the ash to have plenty of time to react with the soil before rapid spring growth. By applying ashes before the planting season begins you avoid risk of tissue burn.
• Wood ashes should not be applied immediately preceding planting, or during early emergence as it could cause short term concentrated alkaline conditions, which could interfere with plant growth.
• Ashes should never come in direct contact with germinating seed or new plant roots because they can cause a chemical burn from the salts in the ash. • Ash may also absorb pesticides if it not given time to neutralize in the soil, so chemical applications should be avoided for three to five days prior to or after wood ash application.
• Ashes that settle on foliage can also cause burning. Prevent this by thoroughly rinsing plants after applying ashes.
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Sources:
http://hubcap.clemson.edu/~blpprt/bestwoodash.html
http://ecgardening.cce.cornell.edu/PDFs/Wood%20Ashes%20Use%20With%20Care1.pdf