Paul Gutches wrote:
I bought a sophisticated pH tester last year and tested just about everything I could think of while the sensor was still viable.
They only last a year or so.
I was testing the pine needle theory, coffee ground theory, and tea theory, plus lots of other stuff.
I'd mix the material with a small amount of water. I did not let it steep long, though in retrospect I probably should have.
Still, the differences in pH readings for these materials does suggest it was working.
Assuming the results are instructive, here they are.
Note in particular the corn-based kitty litter (unused). WoW. It blew away the sphagnum for acidity.
No idea how safe it is for growies, but a selling point on the product is biodegradability.
Note also the spent espresso coffee. Much lower than I'd anticipated.
You might also want to restrict your blueberry water source to (acid) rain.
Acidity
fresh black tea
6.7
fresh green tea
6.2
spent medium roast coffee grounds
6.4-6.5
spent espresso coffee from local coffee shop
5.75
fresh ground dark roast (unused)
6.9
fresh ground light roast (unused)
6.2
World's best ground corn kitty litter
4.4 - 5.2 (!!!)
Well Water (700 feet down into the Taos Plateau)
7.6
Rain Water
5.5-6.0
Diatomaceous Earth
7.6
Sphagnum Peat Moss
5.2
Chopped pine straw
6.3
Wood Ash
10.00
Ace potting soil 7.5
Walmart Steer manure compost / topsoil
8.7 (Yow!)
kelp
5.6
worm castings
7.5