"Part_No" wrote in message
...
I don't know of any test we can do, but
a couple of local gardeners have been using the same stuff for a long
time


The test you can do is to start a few seedlings in it and look for typical
signs of leaf damage common to herbicides. Or you can pay about £100 and
someone else will sprout a few tomato plants in it and look for signs of
leaf damage.

The other gardeners using it for years would be good enough for me though.

Tom