Bayer Advanced 706180A NATRIA Grass and Weed Killer
This is the most effective weed killer listed here, but it not as safe to use as the top 3 on this list. Bayer Advanced 706180A NATRIA Grass and Weed Killer uses relatively benign ammoniated soap of fatty acids, which is essentially the oil from plants mixed into an acidic formula. It replicates a clove oil/citric acid base but the chemicals used are not certified organic and they may not be totally natural. They are biodegradable, so they will break down in your soil, but they can't be used around waterways, and precautions must be taken to avoid breathing in the fumes while clothing and skin must be washed after use.