I once asked what is the correct depth for sowing pasture seed – the agronomists response – first find the moisture.
As an all rounder, a disc drill is a good option. Disc drills are contour following which means the seed is placed at a consistent depth. Drills with fixed tines in contrast can accurately place seed, however in undulating conditions the result is an average as it is not following the ground and at times is burying the seed deeper than usual.
Lighter single disc drills need the ground prepared for them before sowing as the machines only job is to place the seed.
Heavier double disc drills have the ability to contour follow, penetrate, create a tilth and sow seeds directly without the need for cultivation. Renovating pasture would be a typical application.