[header] How to prevent fertilizer runoff [title] Use phosphorus-free fertilizer. [step] 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. 
[substeps] Phosphorous is the largest source of concern when it comes to controlling fertilizer runoff, because it's dangerous to aquatic plants and wildlife. [title] Clean up grass, leaves, and other yard debris.