Note: work done by hired workers does count, however work done on contracted fields does not - you must own the field for the counter to increase. These achievements are also known to be slow sometimes, so you might have to do a little extra.Note 2: This must be done in a single save game, but is not limited to a single session
Sowing is planting seeds, either with a seeder or a planter, or (probably) the specialized potato planter.
Note 3: Seeders and planters that fertilize at the same time may also count towards the fertilizing achievements
Continue this method to unlock: