Josef, thanks for starting this thread. I'm kind of in same boat, trying to do some things with limited equipment. Over time I will be adding implements, but for now trying to make do with shredder and disc harrow.
Late this spring (early June), I wanted to plant sunflowers in some areas, and then okra and peas in some smaller areas. First I mowed down existing vegetation, then used the disc to prep about 3 acres for sunflowers, heavily broadcast the seed, and then lightly ran back over with the disc to bed the seeds. I don't have a sprayer - yet - but thought I might get by. Even though sunflowers grow wild in the rest of the world, I did no get a SINGLE sunflower.
I was doing this on the cheap, so no soil test, fertilizer, weed control, etc., but since sunflowers are growing wild around my fence lines, I thought I should get some. NONE! WTH?
Some of the peas did come up, but they were patchy and the deer mowed them to nubs within a few weeks.
A couple of weeks ago, I decided to try again, slightly modifying the process for oats. In the same fields, I disced heavily and deeper, going over them multiple times in different directions. Since I was broadcast the oat seeds, I doubled the amount I spread, then went back over with the disc lifted to just cover the seed. It rained 1.3" over the next two days, and we've gotten several additional showers since.
This past weekend I checked and did not have any oats poking up, but I dug down an inch or so and had some sprouts which I hope are the oats. Fingers crossed.
If this is unsuccessful, I guess the next purchase is a sprayer, and will be getting soil tested. Just not sure why I can't grow a sunflower with 3oo pounds of seed, when they grow wild in the ditches