Grain drills do a better job of seeding, but also cost more than endgate seeders. Now, with the development of relatively low-cost single-hopper general-purpose seeders, there's a new possibility for seeding mixtures.
Hull, Dale O. and Clark, Maurice L.
"A New Idea For Seeding Grass-Legume Mixtures,"
Iowa Farm Science: Vol. 8
, Article 2.
Available at: https://lib.dr.iastate.edu/farmscience/vol8/iss2/2