Acidifying soil for Blueberries.
I have a question (at the bottom) about how much elemental sulfur to apply. First, some background:
I have 20 blueberry plants on order, and need to amend my soil for them. I just received the results of my soil test, and I have (comparatively) good news! Only 7.4 ph, and 0.5% bicarbonates. That is great news for my neck of the woods (as far as blueberries are concerned) where ph typically is above 8 or 8.5, with bicarbonates comprising up to 20% of the soil!
Until I can amend the soil this summer and give the elemental sulfur time to work (or, more accurately, the bacteria to work on the elemental sulfur, and the resulting sulfuric acid to combine with carbonates to form gypsum), the plants will be grown in pots, with the soil treated with sulfuric acid prior to planting. IÃ¯Â¿Â½m also setting up a venturi injector on the drip system to treat the high alkali secondary water provided here. Got that covered (at least in theory in my mind).
As I understand it, I need about 4.7 oz of elemental sulfur for each square foot of soil per each 1% of bicarbonates present in order to neutralize the bicarbonateÃ¯Â¿Â½s buffering capabilities. So, with Ã¯Â¿Â½% present, I should be applying 2.35oz elemental sulfur per square foot, right? Or am I working with incorrect information? If thatÃ¯Â¿Â½s right, I guess IÃ¯Â¿Â½ll be needing a couple more of the 20lb bags to treat a 5x70 planting plot. 51 lbs total to neutralize the bicarbonates (5 X 70 X 2.35 divided by 16 oz per lb).
Now, how much elemental sulfur would be necessary beyond the buffering neutralization to reduce the ph from 7.4 to 5.5? I havenÃ¯Â¿Â½t found information for that, and IÃ¯Â¿Â½m hoping someone here has some info for me. I'm thinking I'll be applying 60 lbs total, retest, and see where I'm at by the fall, and irrigate with diluted sulfuric acid if necessary to to finish it off prior to planting.
Anything else I should be considering, or math corrections to be made? (and no, I donÃ¯Â¿Â½t need a lecture about the dangers of sulfuric acid Ã¯Â¿Â½ IÃ¯Â¿Â½m well aware and adequately prepared)