The present invention concerns a method for the fumigation treatment of agricultural lands and a machine, for carrying out such method. These method and machine are adapted in particular to perform such land fumigation treatment at a greater depth than the one reached by tools for plowing the land and for earthing big-sized stones and clods. The machine of the invention comprises anchors (4) adapted to open a lenticular recess (6) in the land and sprayers (5) adapted to spray liquid fumigating substances in the lenticular recess (6), these anchors making the lenticular recess (6) without overturning the above land, so that the recess (6) closes itself after the spraying of liquid fumigating substances, preventing the dispersion in the atmosphere of fumes produced by the liquid fumigating substances.