A Gardeners Forum Forums General Discussion Landscape trials and triumphs Confused soil? Help

I have always been told that wood ash makes the ph higher (alkaline). For several years we have put our wood ashes into a large dog house for my fowl (chickens and ducks) as a dust for them to keep critters off. A tree limb fell on the dust house and destroyed it (no fowl injured).

I was walking around with my dad today and we were testing the soil PH (since it was damp). The soil is usually between 6.0-7.0 . In the area where the dust house once stood the PH of wet ashes was below the zero marking and the surrounding soil 3-4 ph. How can this be?

I was using one the cheap probe meters which I know isn't very accurate but, it does give a rough estimate and does work because I put some aluminum sulfate on my hydrangeas and the ph on the meter went from 7.5-5.8 and What is the scoop? Are ashes alkaline or acidic?

From another site

"In addition to its value as a substitute for lime and macronutrients, ash can also supply significant amounts of sulfur, boron and other micro-nutrients."

Sulfer lowers PH right?


lol experts help.

I've always wondered if it mattered what you actually burned? I toss my ashes out directly under shrubbery and spread them out once in a while. I don't test my soil. It has not killed anything yet.

Hi Twizzlestick - I've been doing a lot of reading on this lately. I know that others on this site are more qualified to answer, but I'll throw out what I understand while you're waiting for the experts.

Wood ash should have a ph of 9 - 13. It is alkaline. There is a difference between sulfur in the sulfate form which is a plant nutrient and will not acidify the soil. Elemental sulfur actually acidfies soil, then breaks down into sulfate.

A variety of factors can cause very low pH, if in fact your readings are correct.

You can always do a quick soil test to be sure!

Good luck.

I'm going to get one of the liquid type soil tests and see. I wonder if it being ashes from a wood stove that is controlled burn for hours vs say a brush fire that burns up very quickly is a difference? The wood used is whatever downed trees that my parents pick up for their wood stove. It could be red oak, a little pine (not much), popular, magnolia trees etc.

The wood stove seems inconvenient till the power goes out in the winter and all the neighbors including myself are at my parent's door because they will be up making coffee, cocoa,toasted cheese sandwiches,and soup on top of their stove.

"The largest component of wood ash (about 25 percent) is calcium carbonate, a common liming material that increases soil alkalinity."

"Specific recommendations for the use of wood ash in the garden are difficult to make because soil composition and reaction varies from garden to garden. Acidic soils (pH less than 5.5) will likely be improved by wood ash addition. Soils that are slightly acidic (pH 6.0 to 6.5) should not be harmed by the application of 20 pounds per 100 square feet annually, if the ash is worked into the soil about 6 inches or so. However, if your soil is neutral or alkaline (pH 7.0 or greater), find another way to dispose of wood ash. If you don't know your soil's acidity or alkalinity level, have it tested for pH."

-taken from Purdue University's Hort Page

And I'm with you on a good wood stove being a savior when the power goes out!

Sounds like good information. I knew ash was a good carbon souce for the gardens, however I never really gave much thought to what it will do to the pH.

I love my wood stoves.

i was told wood ashes is great for Onions.

dodge