Realistic Farming and Giants Precision Farming do not share a soil story. If Precision Farming is active on the save, Soil Fertilizer and Dairy Core disable themselves so the two models cannot corrupt each other.
Pro Staff keeps its ladder. Fertilizer and fungicide discounts go neutral while Precision Farming is present.
This is a quiet stand-down, not a crash. You will not get a merged “best of both” mode. Pick one soil story for that save.