You may have heard that using wood ashes on your garden can help make
the soil more fertile. Though ashes do contain significant amounts of
potash, they contain little phosphate and no nitrogen. Most Kansas soils are
naturally high in potash and do not need more. Also, wood ashes will raise
the pH of our soils, often a drawback in Kansas where soils tend toward high
pH anyway. Therefore, wood ashes add little benefit, and may harm, many
Kansas soils. In most cases it is best to get rid of them.
By: Ward Upham