I am working on a mod that changes the way agriculture works in Minecraft. As of now the mod changes the following things:
1) It adds a new "crop" called weeds. Every crop (wheat, potato, carrot, beetroots) has a small chance of turning into weeds whenever they grow a stage. These weeds spread to nearby crops that aren't fully grown if you don't take care of them.
2) Using a hoe to till the ground creates a custom farmland block that doesn't allow plants of any kind to grow unless you bonemeal the farmland. Once a crop has fully grown the farmland underneath loses it's nutrition and you have to bonemeal it again. ( Note: Stems persist but won't grow any melons or pumpkins if the ground is not bonemealed and upon growth also consume the nutrition )
3) You can no longer use bonemeal to grow crops or stems.
4) Pigs have a new AI behaviour that works similiar to sheeps eating grass. But instead of acting as a lawnmower they instead act exactly like a hoe would act on ground ( coarse dirt to dirt, dirt/grass to farmland ) with one addition - they can turn my custom farmland block into it's nutrated state without the use of bonemeal.