I'll preface this by saying I realize this is not exactly in the spirit of FarmRPG (too much realism) and it may be a bit complex to implement at this stage in development, but I do think it provides the opportunity to add some interesting dynamics, so I'll go ahead and suggest it. Maybe someone more creative than me could add a touch of magical realism.
With the town of Redbrook growing every day, more and more land is being converted to farmland. Traditional farming practices can lead to loss of soil health and decreases in water quality but conservation practices can help protect our town.
I think it would be interesting if there were meters that tracked soil and water quality (maybe kicking in once you get the mega farm achievement). Low soil health would create a slight chance for a seed to fail and produce no crop and high health would increase the chance for double crops. Similarly, low water quality could decrease the effectiveness of nets or the chance of getting gold fish. Soil health would decrease if you plant too many of the same crop in a row (especially corn), but you could increase it by planting peas or spreading manure/fertilizer (produced by pigs, perhaps). Spread too much fertilizer though, and your water quality starts to decline. To improve it, you could plant wheat or possibly a new "cover crop" seed.
You could also potentially permanently take a field or two out of production. Doing this would decrease the number of seeds you can plant by one, but could give you a one time or daily silver boost as well as permanently improve soil and water quality. One field could be planted to prairie and the other restored to a wetland. These areas could also attract pollinators, increasing the fruit yield from your orchard, or be small exploring or fishing locations (with items already found elsewhere in the game, so if you don't want to give up the farming space, you don't have to).
There could also be perks associated with this system, either through an existing upgrade store or a new one (maybe another way to spend ancient coins?). Buying things like "no till farming" or "terraces" could add additional boosts to your meters.
