Blocking is most effective when the experimental area has a predictablepattern of variability.
•Experimental plots within the same blockshould kept as uniform as possible.
•If data collection or treatments application could not be done in the same day, the task should be completed for all plots of the same block in the same day.
•If more than one observer is to measurements in the trial, the same observers should be assigned to make measurement for all plots of the same block