In full field and greenhouse agriculture, the subsurface water distribution with underground driplines--subsurface drip irrigation--is advantageous to obtain a better production and a simplification of cultivation practices. This technique can have a major applicative interest on condition that the roots' intrusion inside the driplines irrigators is eliminated or reduced. To reach this goal, a study has been made on vegetable greenhouse cultivations, and on subsurface drip irrigation with underground driplines protected against roots' intrusion with a product containing micro-encapsulated polyethylene Trifuralin (trifluralin). Underground pipes with driplines (without trifluralin) have constituted the confrontation thesis. The trifluralin residues have been determined through GC-ECD, according to different cultivation phases for two entire production cycles: with 30% of leaf covering, at the moment of flowering and maturation, during production and at the harvest ending, on soil, leaves and maturation, during the production and, at the harvest ending, on fruits.