To get the Cultivate X hectares trophies, you have to cultivate in your own land. Go to the shop and buy a cultivator(not plower), note that it works with a tractor attached. Make sure that your tractor is strong enough to pull the cultivator. Attach your tractor to the cultivator you bought at the shop, drive to your farm, unfold and lower your cultivator and drive in to your farmland, you should see a different colour between cultivated land and uncultivated lands. To check how much land you cultivated, press option and scroll to the statics page, note that you don't need to cultivate all the hectares in one session. Cultivation is required after you harvested and before you sow seeds. Note that doing contract does not count towards the total hectares.