Q: Would a lawn fertilizer containing 10% nitrogen produce the same color green as a fertilizer containing 29% nitrogen?
A: The short answer is “yes” but a better question would be how long will the grass stay green after either of these two fertilizers is applied. My guess is that a 10% nitrogen fertilizer is composed of a quickly-soluble nitrogen source. A 29% nitrogen fertilizer is very likely one that has been manufactured to release nutrients more slowly. For instance, if you apply 10-10-10 fertilizer to your lawn, the nitrogen is quickly dissolved and immediately available to the grass once it’s been watered in. The grass would grow rapidly for a couple of weeks but would need more nitrogen after that. On the other hand, a 29-3-4 fertilizer would release some of its nutrients immediately to the grass but would continue to release more over several weeks’ time. These controlled-release fertilizers are great for lawns because lawn grasses prefer to be fed gradually rather than all at once.