Answer: If your soil is alkaline, there are a few ways to make it more acid (lower the pH). First of all, if possible have your soil's pH tested, so you're sure it needs modifying. <br><br>You can lower soil pH by adding powdered sulfur, gypsum (calcium sulfate), iron sulfate, or aluminum sulfate. The addition of large amounts of organic matter, such as compost, leaf mold, or peat moss tends to lower soil pH slightly. I'm not sure what you mean by "natural" vs. "artificial". I supposethe most "natural" way is to add lots of organic matter over time, though this would be a slow process and could take several years.
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