Do you plan to plant next spring? It sounds like that from some of your questions, so that is where I will go. I would get the soil test this spring. If you do need lime, that should be applied this fall. Fertilizer can also be applied in the fall, but you do not want to add nitrogen in the fall if you live in a wet area. Both the fertilizer and lime need to be worked into the soil. Fertilzer can be put on in the spring, and it is best to put on large amounts of N (such as for corn) in rainy climates in the spring.

I would spray the meadow in early fall, about 1 month before most plants go dormant. Mowing 2 weeks before spraying will help if you have tall weeds that will not allow you to get good spray coverage, and you do want the weeds to be growing and not going to seed. Regular mowings during the summer will also kill some weeds, and keep seed production lower this year. Use 1 qt/acre roundup with 1 pint/acre 2,4-D. Consider 2 qt/a roundup and 2 pt/a 2,4-D if you do not need to add lime, and are not planning to till in the fall. Wait at least one week, and the weeds will be dead. Apply your lime and any P-K fertilizer, and work into the soil. If you do get any regrowth or seeds germinating, you can spray with roundup in the spring 1 week before planting, and/or rework the soil (and add any fertilizer, especially N fertilizer) before planting.

Good luck, and I am sure other guys here will have some good ideas for you as well.