mostly the extra amount of grass seed needed to achieve the same stool, costs more than the extra cost of seeding by a contractor with professional machinery
Tume and Elho pneumatic fertilisers are best for seeding hay fields. Actually those are feeding seeds with same principle as seeding machine does. Centrifucal fertiliser isnt as good, but it works. You must maybe have more seeds than otherwice. Offcourse only for sure
By the way, have you allready bought your seeds? There is no good seed at spring anymore Last summer was horrible and seeds did get ruined last summer here! Keep busy and buy those seeds now.......