Archive for Sunday, December 15, 2002

Fireplace ashes need to be disposed properly

December 15, 2002


Many people prefer the warmth and smells of a real wood fire. The snaps, crackles, and pops add magic and excitement to any family gathering. But after the hot embers cool, and a pile of ash is all that remains, homeowners are left wondering what to do with all those ashes.

A simple and convenient solution is the dump them on the compost pile. This, however, may not be the best use of such a potentially hazardous material. Here are some hints to help you safely dispose of large quantities of fireplace ashes.

Wood ashes contain no nitrogen(N), it is lost during the burning process. Likewise, they contain little to no phosphate(P). The only valuable nutrient in wood ashes is potassium(K). Unfortunately, in most local soils, the levels of K are quite high and little extra is needed. In fact, it is stable in the soil and does not leach out. The only way potassium is lost is by plants using it for growth and development. This is why a soil test is recommended before adding nutrients. It is difficult to know what is needed when you do not already know what is available.

Another problem is that wood ashes function like lime to increase the pH of soil. Here again, in our area, soils are calcareous or derived from native limestone. The pH is mostly neutral so the use of lime is not necessary. The increased lime may raise your soil pH to an undesirable level. So, the benefits of wood ashes in most garden soils is not all that great.

To use wood ashes to their greatest potential, mix them with the compost pile to create a more balanced fertilizer product. Likewise, compost is usually slightly acid so ashes would raise the pH to a more desirable level. Long story short, wood ashes are better mixed with some other source of organic material rather than being applied by themselves.

However, if you do decide to apply wood ashes to your garden or flowerbed, spread them in a very thin layer and never in a concentrated amount. Likewise, rotate the areas that you apply them to so that you do not drastically influence the soil you will be planting in next year.

- Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.

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