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How long for pH to drop?

3102 Views 15 Replies 8 Participants Last post by  Ridgerunner
How long does naturally acidic soil take to drop?

My UMass test came back with a neutral 7.0 pH. Around here, soils naturally tend to the acidic side and lime is typically an annual exercise. I very rarely lime as I've tended to neglect my lawn. I did a bag (40 pounds?) of dolomite on 2,500 SF around May. Last bag was 2-3 years prior. And then I discovered TLF...

I would like a soil at 6.5-6.8 in the spring. Should I apply gypsum or wait for a natural drop?

Modified Morgan extractable:

Potassium is low at 71 ppm

Ca:Mg seems crazy.
Calcium at 1336 ppm
Magnesium at 276 ppm

Shouldn't that be almost the other way around?

Base saturations:
Ca: 73%
Mg: 25%
K: 2%

CEC: 9.1

My thoughts are to throw some fast-acting gypsum and sulfate of potash at it. Light doses. See what happens.

I don't think the pH is the end of the world but the Ca:Mg looks like it could be a problem.

1. What affect will potassium have on this whole balance?
2. Will pH correct itself in a year or two or should I address it now for best results?
3. Do you think one bag of dolomite earlier in the year had that much of an effect?
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Yes, aim for pH 6.5 to 6.8 for optimum nutrient availability. If you are already at the high end of Ca base saturation (i.e. >65-75%), then look to elemental Sulfur. Available at ag/coop centers. Golf courses here are starting to use a form of slow-release S. I use a product called Steric S. And you are also on the right track with humic acid - temporarily increase the cation exchange. Also, anything to improve the soil's biology, such as compost topdressing or liquid biology amendments will help break down nutrients. Think of this whole process as stepping on the gas pedal for a period of time.
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