If you have docks, thistles and nettles, strimming or scything them down will weaken and eventually kill them. I always wait until they are just about to flower then hack them down - very therapeutic, good exercise and less damaging than sprays.
I agree that ragwort is best dug out and burned.
We harrow all the paddocks hard in the spring, then lightly as stock moves off during summer to break up and spread the muck.
Top as required.
I'd recommend soil testing for P,K and pH - you can then get a contractor to spread whatever you need.