My $0.02 worth, all for less than $0.02!
BEST WAY TO RE-SEED PASTURES.......
And now, to complete that sentence. (Choose any and all options that fit your conditions)
(1) ....with what equipment I have available
(2) ....with what equipment I can rent/hire
(3) ....and continue to use them
(4) ....in the spring
(5) ....in the fall
(6) ....and Fertilize in the fall or in the spring
(7) ....while correcting soil Ph conditions
(8) ....depending on what species of grass you have and/or choose to grow
1A through 6A are the same, only starting with heavily compacted soil.
1B through 6B, same with severe weed infestation.
I farmed for 36+ years before deciding I needed a break and a real estate developer needed my farm. I ran cows on my pastures, but big ol' hairy animals that eat hay are all the same to grass and dirt. They compact the soil, eat the good grass, leave the weeds, and promote poor soil conditions.
First, and you'll be our eyes in the field on these, do you have a problem with noxious weeds? Has this land been used as pasture in recent years? (If so, likely it's compacted) If you have weed issues, the VERY FIRST thing you want to do is treat them. Spray or granular application weed control is the BEST route. Old school thought was to bury the weeds. (plowing) That takes your pasture out of rotation for AT LEAST a full season until soils stabilize enough to run animals without tracking too much in wet weather. (Not to mention added machine cost/requirements) If compacted, and that is serious enough, soil may benifit from some sort of tillage. Best is to remove land from pasture rotation a few years and let freeze/thaw cycles do the job natures way. Short of that, chisel plow or subsoiling is next best. Again, if you plan on USING the pastures, this isn't a viable option.
Next step is to determine soil nutrient levels. Get a soil test. Does it need lime? N,P, & K? Micro-nutrients? Get your County AG extention agent involved. They'll be more than happy to make localized recomendations based on soil test results. They will USUALLY even go as far as to supply the bags to package soil for lab testing. In my area, a soil test will cost $15 per sample/test. The County AG Dept will also make suggestions about timing of fertilization based on local climate, products needed, and current soil conditions. Soil with incorrect Ph level will not benifit from fertilizers, no matter HOW much you put down. Micro nutrients effect plant growth in much the same way. (Around my area, we USUALLY need a dose of boron every few years to promote healthy plant tissue growth)
Best time to seed for most all grass types is the fall. Spring is OK, but your new grass will go immediately into hot, dry summer with little root growth. Seeding in the spring, grass has all the water it needs short term without rooting deep. Then when summer sets in, it's too late. A few dry months and you're right back where you started. Seed in the fall, and the young grass will root deep and continue to grow until the ground freezes hard. By spring, you have a hardy, healthy young grass plant that's chompin' at the bit to start growing above ground.
If you plan on doing any "dirt work" (ie. leveling, grading, filling) do that BEFORE you seed. Grass seed likes contact with soil and NOT being buried. It germinates best in the top 1/8" to 1/4" of the soil, where sunlight and warmth can do its thing.
I always rented a "no-till seeder". They are available through county AG dept here. What would be commonly used on a farm would PROBABLY be over-kill for your use as well as a little on the big side for your tractor. I'd check with local equipment dealers and better equipment rental shops to see about a "power seeder" or overseeder. They are commonly used to re-seed lawns. Dirt is dirt....grass is grass. A pasture is just a big lawn that you keep horses on. The power seeder will put the seed where it's going to do the best and do that in a very consistant, accurate way. There are dozens of brands of power seeders. (Brillion, Woods, LandPride, Jacobson, ect) 4' and 5' models are common. Your tractor should be able to handle one with little effort. In so many words, you'll get far better results with a power seeder than you could ever hope for by simply throwing seed on the ground and raking it in.
I've seen hundreds of cases where people would pay good money for certified seed, prep and then broadcast the seed on already existing grass, drag a piece of chain link fence or something simular to rake the seed in, and wonder why 3/4ths of their grass didn't germinate. It's just not a sound way to re-hab pastures.
Once you have new growth, you SHOULD hold stock off the young grass for a while. The longer the better. That might not be possible, ESPECIALLY if you do BOTH pastures at once. You might think about doing one this spring and the other in the fall. Or even one this year and the other NEXT year. Let each new stand have a chance to harden off before turning the horseys loose on it.
I can't stress enough the value of your County AG Extention Office/Agent. LIke I mentioned, their advice will be localized, where I'm giving you generalizations and my experience based on my conditions. That's what these people are there for. Use 'em.