Lawn Impact

• If you use too much compost as a natural fertilizer for your lawn, you risk killing your lawn. Compost can smother your lawn in much the same way that leaving a pile of leaves in your yard kills the grass beneath it. Lawn care experts at Gardenweb.com recommend that you use only 1 cubic yard of compost for every 1,000 square feet of lawn. Essentially, the goal is to add only one-third inch of compost uniformly over your lawn.
  
  If you are using a protein-based organic fertilizer, it is more difficult to apply too much. This only happens if you apply so much that it smothers the grass. Otherwise, it simply stays on the soil until microbes eat the protein and realize the nutrients from the protein back into the soil. In fact, the University of Illinois Extension says the nitrogen level in organic material is so low that the greater problem is using too little on your lawn. Knowing how much to apply requires an understanding of the nitrogen level ordinarily present in your soil and the amount of nutrient in your organic material. To establish this, test your soil with a self-test kit available from your local garden center or provide your local extension office with a sample of your soil. You also need to know how much nutrient is in your organic fertilizer. Some organic fertilizers provide this information on packaging. Otherwise, you need to have your organic fertilizer tested. One Oregon gardener established that many organic fertilizers feature 12 percent nitrogen, 11 percent phosphorus and 2 percent potassium. A 100-lb. bag of that fertilizer contains 12 lb. of nitrogen, 11 lb. of phosphorus and 2 lb. of potassium. Compare that with what is provided by a chemical fertilizer. Your lawn needs the same amount of nutrient regardless of how it receives it.
  
  

Environmental Factor

• The environmental impact of organic fertilizers is much lower than with chemical fertilizers. Organic fertilizers are proteins that must be eaten by microbes before they release the chemicals featured in traditional fertilizers. While the proteins can be washed away in heavy rains, they are less likely to be carried to rivers, streams and lakes. It is in these waterways that traditional fertilizers do most of their damage by impacting the chemical components that provide for a healthy balance between aquatic animal and plant life. Manure, though, is an organic fertilization substance that has many chemicals already active. Manure can cause pollution when it drains into waterways. Applying too much manure increases the likelihood that it will drain into waterways.
  
  

Other Considerations

• Plants do not know the difference in the source of the nitrogen they consume, but the source can play a role in a lawn's health. By using too much chemical fertilizer, you can burn your lawn. Essentially, chemical fertilizers feature a salt component that, when over-applied, causes the grass to die. Organic fertilizers, though, do not include salt. Therefore, they will not cause a lawn to burn. While over applying them might have other consequences, lawn burn is not one of them.