This principle does not apply to mixed crops (these are crops grown and harvested together on the same ground, e.g. mixed corn), or to successive crops (e.g. barley undersown with clover for later harvesting).
To načelo se ne uporablja za mešane posevke (to so posevki, ki se posejejo in pospravijo skupaj na istem zemljišču, npr. mešanica žit) ali za naknadne posevke (npr. ječmen, podsejan z deteljo za kasnejše spravilo).