Soil Degradation

Soil would slowly degrade over time, after being tilled. Eventually, soil degrades down to sand, then, if you plant a cactus or otherwise plant stuff in sand, it dissapears entirely, or if Mojang puts work into it, turns to white sand, that can be used to make glass but nothing else. There would be 5 tiers of soil: 1: fertile, 2: its dirt, 3: sandy, 4: sand, 5: unusable. All dirt starts at either "its dirt" or "sandy." Obviously sand, well, under the sand category. To replenish one tier, add Compost from compost bins, Bone meal, Eggshell/Egg. To boost it 2 tiers, add "Balanced Compost." or "Chemical Fertilizer." For Balanced Compost, you add 1 compost, 1 bonemeal and get 2 balanced compost. For chemical fertilizer, you add 2 coal/charcoal, 1 plant (any) and burn it in the furnace. This yields 2 chemical fertilizer. Sand needs a tier 2 fertilizer and it only replenishes 1 for sand. Eg, using balanced compost on sand makes it "sandy." Unusable cannot be fixed. Fertile is the highest tier, so fertilizing just works like bonemeal in the current game. In general, every third crop you grow lowers it one tier.

Actual thing for each crop:

Wheat- 4 crops

Carrot- 3 crops

Potato- 2 crops

Melon- 1 crop

Pumpkin- 1 crop

Beetroot- 4 crops (a reason to grow beetroot?).

Fertile Soil- grows x2 as fast - Its Dirt- normal - Sandy- 1/2 as fast - Sand- doesn't grow. 

The only use for white sand is that it makes twice as much glass, if implemented.