My understanding is that the Ukraine grows and exports a significant amount of grain, and that the leftover dust from depleted uranium rounds is pretty dangerous.
Look at the rates of birth defects and cancer in Falluja to see the answer to that one.
The Donbas is actually the least agriculture intensive region of Ukraine, iirc about 10% of production. Ukraine is using DU because they know they are going to lose and wish to simply punish the Donbas for an eternity.
The infected soils won't just stay in Donbas, but the Westerly wind will generally take these soils further EAST into Russia and the steppe.
Uranium isn't as bad for wheat as it is for root vegetables like carrots and turnips. It could be an occupational hazard for those who are tilling the fields though.
