About the seeders (Farming Simulator 2013)

Can't figure what the hell... what was playing, always been the case that you hire a worker to sow the field and the grain drill is not being used. Now the seeds are consumed.
Or in the beginning of the game start to sow the seeds manually consumed, hire of the employee, the seeds are not consumed. play on, buy more seeders, hire worker and seeds are consumed.

Maybe somebody knows what the heck is that ?