By adding biology/soil life in the form of organic matter, often the community/soil food web underground helps you achieve more than you could possibly afford to purchase in fertilizer.
To be sustainable, use what you already have on site, what you know and trust. Your own source of leaf litter or compost is important. If that's lacking, you can establish a cover crop. This will help soil porosity, bring up nutrients and later add organic matter once it's tilled in at the end of its growing season. Use soil test results to determine if there are any particular nutrients lacking. Often times, you will find the acidity or alkalinity is not the correct range to make the nutrients available to your particular kind of planting. This can easily be remedied with materials consistent with organic practice.
It's more likely, if you are in a newer area that has been deforested for a long time or the topsoil moved or removed, you will find that organic matter is less than 5 percent of your soil. To bring that organic matter up to 5 percent, you can cover crop, use your own compost or leaf litter or purchase organic matter in the form of professionally made compost.
If you've done everything the soil test analysis and your coach recommended and are not seeing healthy, growing native and drought-tolerant plants within six months, get professional help.