bpgreen soil test 2020

[bpgreen]

I've been rereading this and came up with a rather geeky question. You said that sulfur goes through a reaction where it converts to sulfuric acid. I thought it converted to sulfurous acid.

It's not a big deal (a difference of one oxygen molecule), just a curiosity. Maybe the conversion is different when it happens at three surface vs underground.

[andy10917]

I checked my source for that information, as while my knowledge of chemistry is pretty strong, it's coming up on 50 years ago. My primary source of the information is Michigan State University (and others agree):

Soil bacteria convert the sulfur to sulfuric acid lowering the soil pH. It is important to note that this is a biological process (slow) and not a chemical reaction (rapid). The bacteria are active, when the soil is moist and warm. The soil temperature needs to be above 55F. The bacteria are not active in the winter so fall applications of sulfur have little effect on the soil pH next spring.

I'm not a fan of surface-applied elemental sulfur, as I have seen the yo-yo effect on pH as the bacteria are active at some times and inactive at others. This leads to rises and falls in pH, and changes in soil interactions.

So, whether sulfuric or sulfurous, there is an undesirable activity from a very-low pH (highly acidic) substance that varies in it effect as the seasons change. I have no idea about how much of this occurs in incorporated soil, as that doesn't really apply well to soils with lawns on them - very few people are going to rototill the lawn to get the Sulfur incorporated for a temporary boost (which should be quite temporary in a calcareous soil).

[MorpheusPA]

Surface-applied, if memory serves, it mostly gets lost as sulfur dioxide (smog). Which isn't great for the atmosphere, although amounts are minor compared to industrial output.

Dug in, in a calcium-heavy soil, sulfur-loving bacteria aren't going to be particularly active since the pH is so high. Their enzymes work best at neutral pH or lower. It's one of the great paradoxes of pH management...it's easier to lower pH when the pH is already lower than you'd bother applying sulfur.

[bpgreen]

Sounds like it's not going to help much in the long run, whichever acid it creates. I've seen that since it only keeps the yellow out for a few years. I'll probably bury the sulfur a few more times, but not buy more.

I think the explanation I saw for sulfurous vs sulfuric acid was h₂o + s + o₂ = h₂so₃

Of course, it's easy to get to sulfuric if we double the equation and add another o₂