Moderation is what I aim for, from the widest variety of materials possible. Too much of any 1 thing could be detrimental, but hardly anything would be harmful if spread around in trace amounts though, over time, if it's something of an extreme PH and is used alone repeatedly, results could eventually be disappointing.
Whatever organic matter your home/property generates can be composted, either in a pile or bin, or by other methods, or spread around as you described regarding the ashes. A well-varied mix of organic matter will help dramatically improve any kind of soil, from clay to sand, adding tilth and fertility, moderating moisture levels. Any plant can only be as good as the soil in which it is growing, so whatever one can do to improve it is worthwhile, very rewarding. Don't think you will always have clay soil if you want to change it to "black gold" garden soil.
15 mins of very valuable info:
http://permaculturenews.org/20...
