I have been using wood chips for years as mulch around perennial
flowers. Seems to do a lot of good, and I have never noticed any
problems. I do simply put it on the soil, I don't mix it in.
Unfortunately, we now have a power plant in the area burning chips to
produce electricity, making it harder to find chips. A few years ago
they were selling for $7 a cubic yard. They quickly went up to $27 or
$30 a yard and last year were hard to find at all. When good ideas get
around, prices go up......
anthony Massachusetts, zone 5