Monday, April 7, 2008

How to Adjust your Soil’s pH?

Of course you can adjust your soil’s pH! Gardeners do it all the time when they know their lot in life is extreme soil, or even when they’re just trying to please some special fussy plant. It’s not a big deal. You just dig in something that nudges the pH in the direction you want it to go:
  • If your soil is too acidic: To raise the pH, dig in dolomitic limestone, bonemeal, or wood ashes. How much? I knew you were going to ask that! The answer has to do with how much ground you want to alter or improve. If you really need to adjust the pH, I strongly recommend you get that lab-analyzed soil test, because the lab can give you good, tailored directions on what to do and how much amendment(s) to add. Just so you know, though, the general rule of thumb for adding granulated limestone is between 5 and 10 pounds per 100 square feet of garden area.
  • If your soil is too alkaline: To lower the pH, dig in some acidic organic matter such as peat moss, sawdust, well-chopped leaves from oak trees, or pine needles. Alternatively, you can add calcium sulfate, iron sulfate, aluminum sulfate, or powdered sulfur. If you don’t let the sawdust, leaves, or pine needles decompose somewhat before adding them to the soil, they can leach nitrogen from the soil as they break down. And too much peat moss can waterlog the soil as well as make it quite acidic. Consider adding no more than one part of organic amendment to three parts soil. You need professional advice on application rates if you decide to go with powdered sulfur or other additives.

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