I would assume you have removed the stumps and can use tillage equipment on this pasture ? If so, you should prepare the soil for a good seed bed, would also be highly beneficial to check the PH of the soil, correct that as required, with lime, and also check fertility. If either are off, lacking etc, the results of what you plant may not be very desirable or what you want.
We used set the grain drill for about 3 bushels of oats per acre, but that was for a grain crop to be harvested, you can broadcast them heavy, they will come up thick for grasses. The will shade out weeds and are seemingly aggressive, and good for a cover crop. Grass seed you will have to do some research, not sure what the application rate is, what you are using to plant them.
I've done areas almost as big by hand, due to the lack of implements. Oats are a larger grain/seed can go a little deeper in the soil. If you are not using a drill, you can moldboard plow, go with one pass on the disc, broadcast the oats, and you can use whole oats from the feed store for grasses, I do it all the time. Then one more pass on the disc, if this is a heavy disc that cuts deep or other implement that tills deep, you will have to be careful, you don't want the seed to deep, this method kind of duplicates what a drill does and I have had good results here with it, for the lack of having a grain drill. After that last pass and the oats are set, I would broadcast the grass seed, and roll it with a double roller cultipacker, this should set the grass seed with enough soil contact, firm up the seed bed etc. Also be aware too many passes after initial tillage can compact the soil too much where the tire tracks are etc. I mention these methods above, as I use them as an inexpensive option, I'd prefer to have a grain drill with the grass seed boxes and do both at the same time, then roll with the cultipacker. The icing in the cake would be a mulch layer, this covers any remaining seed on top, confuses birds, so you won't likely have seed losses due to bird pilferage LOL ! Done right it will come up nice and at some point late on, cut it, high, then those grasses will come up, oat grasses will come back if there is enough rain, weather plays a role in all this, but after that first cutting you'll see whats under and coming up, let that get established, might be able to graze it, but the following year would be better, you don't want to undue what you did and have weeds take over, its possible you won't have to spray for weeds, I can get away with not doing that here on my food plots, oats sure can shade them weeds out and that grass coming up behind it helps. I like to plant heavy with seed, you don't do that for a crop, but for grasses, I think it helps eliminate weeds without having to apply weed killer, with crops we had to spray so to get clean straw for sale after the harvest. Oats do like lots of nitrogen, so fertility is important as is PH.
