_I will make this statement now, you can disagree if you want to. There is no reason why any person on this earth should put synthetic fertilizer on their lawn or on there crops! Period! End of story!
What is so bad about synthetic fertilizers you ask?
First they can burn your lawn if you apply them wrong. Small potatoes in the grand scheme of things.
Second, they work fast, many of them too fast. They promote "top growth" before the roots of the plant can catch up. This leads to unbalanced development.
Third, they can kill beneficial organisms that are responsible for decomposing organic matter and developing soil structure. Using synthetic fertilizer starts a vicious cycle. When it is used up your lawn has less organic matter than it did before and the only way to give it a boost is to add compost (the smart way) or more synthetic fertilizer (the other way).
Fourth, synthetic fertilizers kill fish hundreds of miles away. No joke, the large amounts of nitrogen in many synthetic fertilizers cause "dead zones" in coastal waters. What are dead zones you ask? "Overuse of nitrogen fertilizers are a primary cause of "dead zones" in coastal waters because nitrates are highly soluble; any nitrates not taken up by plant roots move quickly down through the root zone and enter ground water. When nitrate-laden rivers enter bays and estuaries, the excess nitrogen can cause larger than normal algae blooms. Decomposing algae draws oxygen from the water. Too large a draw down of oxygen renders the water incapable of supporting most aquatic fish and animal life; anything that cannot swim or crawl out of the dead zone suffocates. The Mississippi River fertilizes a dead zone in the Gulf of Mexico that fluctuates in size from 3,000 to 8,000 square miles." (Deborah K. Rich, 2006, San Fransisco Chronicle).
Fifth, nitrates in synthetic fertilizer don't just kill fish. High levels of nitrates in drinking water and well water (how do you think they got there?) have been linked to bladder and ovarian cancer in humans and also to various cancer in animals. It is possible that up to 50% of the synthetic fertilizer added to your lawn breaks down so fast that it leeches right past the roots of your grass and right in to the ground water which can flow into your well or the next closest body of water. Aside from all of these other facts, if up to 50% of it misses its intended target and doesn't even feed your lawn, aren't synthetic fertilizers just a giant wast of money too?
As a lawn care professional and a landscaper, I really don't stand to make any more money by telling you to use natural fertilizer over synthetic. Natural fertilizers will not work as fast as their synthetic counterparts so a natural lawn will not turn green as fast as a synthetic one will. Although, the nutrients in the natural fertilizer will break down slower and feed your lawn for a longer period of time. Natural fertilizers will promote root growth as well as plant growth over a longer period of time. Natural fertilizers will not burn your lawn. Since the amounts of nitrogen are lower in natural fertilizer and because natural fertilizer takes a long time to break down, there is little to no leeching into the ground water.
Everyone has heard the old adage, "slow and steady wins the race,". That is natural fertilizer in a nut shell. It will feed your lawn, last longer and not harm the environment or the people or animals in it. That is the clear winner in my book!