In regard to herbicides that do the most damage. Its usually the residuals. Triazines(atrazine), sulfonurea(metsulfuron), imidazolenes(imazapic), trifluralin and especially pyridines(clopyralid). Reducing or rotating around glyphosate where possible def should be a goal.

Fulvic acid around 100g/ha is what we use, liquid versions can be all over the place. Better standards and labeling here would be good. If you use fulvic, citric acid to reduce tank pH to under 3.5 you should be able to experiment with reducing glyphosate by 30%

Hope this helps

Brad