CONCLUSION AND RECOMMENDATIONS Hence future study on the effect of fertilizer levels, (same levels) on tomato yield using the same sites as the locking factors may not be blocked. In a general note this case of tomato yield has provided us with evidence that not in all cases that blocking could minimize experimental error. is therefore important to investigate at the design stage whether blocking should be introduced or not. It is therefore recommended that experimenters and agronomist should subject individual crops to field experiments before choosing a suitable design for it.