hi there, i have a new area of blueberries that i just transplanted that look like the this: i dug 8" and mixed in a couple of bails of peat moss and 1.7kg of aluminum sulphate. a month later i've take a ph reading with the following device: it maybe barely moves from a ph reading of 7. can a device like this be trusted? irrespective, would it hurt to mix in another 1.7kg of aluminum sulphate? these bushes won't have much of a root system yet so its easy enough to do now. appreciate any guidance!
I hope that you didn't really use aluminum sulfate; see this website: https://hortnews.extension.iastate....te should not be,be toxic to blueberry plants . Perhaps you meant ammonium sulfate, which is commonly used to fertilize blueberry bushes. I used sulfur to lower the pH of the soil for my blueberries, and it worked well. Regarding the pH meter, this type of instrument is known to be very inaccurate, especially if you just push the shaft into soil. I have an identical-looking unit that wasn't too bad when I calibrated it in a dilute solution of vinegar, but it proved to be practically useless when just shoved into the soil, even damp soil. I had better results when I made a small depression in the soil, added neutral pH water, and mixed the soil and water into a slurry before inserting the pH meter. That was some time ago, but recently I used the meter again and found that nearly all of the readings were near 7.0. I've read that this type of meter loses accuracy with age; so, that could explain it. I just read the instructions on another similar meter that I just took out of its package, and it states that besides wiping the shaft with a clean cloth after each use, it should be brushed with sandpaper, something I haven't been doing. When I get the chance, I'll try using both meters in the calibrated vinegar solution and then in the blueberry soil, wiping with cloth and sandpaper between readings. The coloured paper strips are supposed to be a more accurate way of measuring pH.
Ugh! I did use aluminum sulfate! Do I need to dig this all out and replace the soil now?! Where can I buy ammonium sulfate or sulphur in Victoria, BC? any advice greatly appreciated!
the space is 230 square feet and i used 1.7kg of aluminum sulfate. unfortunately, websites like https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/aluminum-in-garden-soil.htm still suggest aluminum sulfate for blueberries. the recommendation is .5 kg per 10 square feet... so, i'm hoping that my 1.7kg hasn't really made much difference. not sure where i can get soil test in Victoria, BC? do regular soil tests screen metals?
Since aluminum sulfate is soluble in water, if the subsoil under the blueberries is porous (permeable) enough, you should be able to leach most of it out of the topsoil by watering thoroughly for a long time. You can test the soil's porosity by following the instructions in this website: https://www.direct-drainage.co.uk/blogs/septic-tanks-faqs/how-to-do-a-percolation-soil-porosity-test . Since you want to drain the top 8" of the soil, you should dig a hole 20" deep and 1 foot cubed at the bottom, in a location near the blueberry bushes. Then you can measure the time taken for water to drain as described in the article. It suggests a maximum drainage rate of 100 seconds per mm, or about 42 minutes per inch, which should be adequate for your purposes. You don't need to worry about draining too fast. You should be able to buy ammonium sulfate (21-0-0) and/or sulfur at a farm supply store like Buckerfields, which has three stores on the island, including one in Duncan. I got my supplies at Otter Coop in Aldergrove. By the way, it's not a good idea to use fertilizer on recent transplants; it might burn the tender new roots. A slow-release rhodo fertilizer would be better than 21-0-0 if you want to fertilize this year. [Edit:] Rocketboy, I didn't see your last comment before posting the above; I don't know the answers to the questions raised.
