When you do this, you're adding a bacteria to the soil that will fix nitrogen from the air. The plant can then use this nitrogen to grow. Organic gardeners use pesticides. I've heard some talking about them. So you're no better than a synthetic gardener.
Organic gardeners use a variety of natural sprays to control insects.
Some of the stuff is found in the kitchen, and you could eat it for dinner. Some of the stuff is more dangerous, like pyrethrin, rotenone, sabidilla dust, nicotine spray, and neem oil. These act like their synthetic counterparts in that they kill insects indiscriminately and upset the balance of pests and predators that you're trying to establish in the garden. A lot of organic gardeners don't use these at all. If you're desperate and feel you must use a spray, these chemicals can be kinder on the environment.