I use 2-4-d armine on our pastures for broadleaf kills with no harm to grasses in the early spring. I also use butyrak 200 on my clover plots. It kills all broadleaf weeds except clover and does not harm the grass.
hope this helps.
CWT
If it's weeds you want to get rid of, go to Tractor Supply and get some Pasture Guard. Will do little harm to clovers and cereal grains if you have those in the plots but will get rid of stuff like thistle. About $29 a gallon.