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Go right ahead, Lois. It's Go right ahead, Lois. It's true that fresh oak leaves contain acidic compounds, but the decomposition process neutralizes these acids and shouldn't affect the pH of your soil. Running a lawn mower over the leaves to chop them will produce a better-quality, better-looking mulch that will decompose more rapidly and won't be so likely to blow off in the wind. Most experts reommend having your soil tested every two or three years, not just to determine is pH, but also to check the levels of plant nutrients. Here's a good fact sheet on organic mulches.

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