I am often asked questions like this one. “What is the best natural fertilizer for your lawn? I would like to use something that I would not have to worry if it would burn up my lawn if to much was applied. What do you think about 10-10-10 fertilizer?”
10-10-10 is a great all purpose fertilizer when used in moderation. But it is not ‘natural’. It can certainly burn your lawn or plants if it is over applied. It can also actually do harm your soil if too much is used.
As far as a great natural fertilizer, Compost and composted cow manure are great. However, most people don’t have access to the volume necessary to effectively cover their lawn surface. If you are one of the lucky ones that do, be sure the manure is thoroughly composted or it too can burn your lawn. But once it has mellowed, it is harmless (except for the weed seeds) and very high in nitrogen and soil building properties.
A packaged product that I really like as a natural fertilizer is Milorganite. You can read more about this product on their website.