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How to prevent fertilizer runoff
Use phosphorus-free fertilizer.
Most fertilizer bags will have a ratio of nitrates-phosphorus-potassium printed on the outside of the bag. Look for a number like 32-0-25, where the middle number, denoting phosphorus content, is zero.
Phosphorous is the largest source of concern when it comes to controlling fertilizer runoff, because it's dangerous to aquatic plants and wildlife. Clean up grass, leaves, and other yard debris.