I have an idea. Both the field (plot_field_temp.xml) and the wheat (farming_wheat_harvest_a / farming_wheat_harvest_b) have extra materials. Maybe @LordGood know more of what he wanted to achive.
material (basic_trans.xml) required textures:
material (basic_trans_wind.xml) required textures
So my uneducated guess @vladislavbelov, @wraitii would be that the game is somehow having fun swapping those unused textures because one shader still calls them. It usually uses the one it finds around like the palisade here.