Sue, the techniques you're talking about fall under the umbrella of "no till" (also called "zero till") farming. Much lighter on fuel, but heavier on herbicide application. In some soil types, it apparently works. In others (heavier clay based soils) some tillage is still required.
An air seeder is used for this type of planting. The old style mechanical seed drill isn't suitable for no till work. The ones used on the farmland around me are massive. But they are still pulled by a (huge) tractor and powered by the PTO (power take-off).
I haven't seen one suitable for a small tractor, and I suspect it isn't possible given the horsepower required. But there may be mini units for small-scale operations.
Anyway, search "no till farming" and "air seeder" and you'll have links galore.
Cheers,
-Doug