Plant for digitally printing a sheet fibrous material, wherein said sheet fibrous material is fabric, knitted fabric or non-woven fabric, said printing plant comprising: - at least one conveyor belt exhibiting an exposed surface configured for receiving the sheet fibrous material, the exposed surface defining an operative tract configured for temporarily receiving in contact a first side of the sheet fibrous material and - during a predetermined operative condition - for continuously moving said sheet fibrous material at a speed constantly greater than 0 along an advancement direction, - at least one station for preparing the sheet fibrous material, operating at the conveyor belt and configured for treating at least part of a side of the sheet fibrous material, said preparing station being configured for placing on the sheet fibrous material a treatment composition comprising at least one of a treatment liquid and a treatment foam, - a printing station, placed downstream of the preparing station, adapted to digitally ink-print at least part of a second side of the sheet fibrous material opposite the first side placed on the operative tract, the printing station comprising a printing module which, during said predetermined operative condition, is configured for: o defining a print on all a width of the sheet fibrous material, said width being measured normal to the advancement direction, o staying in a fixed position and printing the second side of the sheet fibrous material sliding on the operative tract, characterized in that the preparing station is configured for placing, on the sheet fibrous material sliding on the operative tract of the conveyor belt, a predetermined quantity of the treatment composition, said quantity of the treatment composition being selected so that the sheet fibrous material itself exhibits a weight percentage per square meter variation, between a section immediately upstream and a section immediately downstream the preparing station, comprised between 10% and 50%. - at least one conveyor belt exhibiting an exposed surface configured for receiving the sheet fibrous material, the exposed surface defining an operative tract configured for temporarily receiving in contact a first side of the sheet fibrous material and - during a predetermined operative condition - for continuously moving said sheet fibrous material at a speed constantly greater than 0 along an advancement direction, - at least one station for preparing the sheet fibrous material, operating at the conveyor belt and configured for treating at least part of a side of the sheet fibrous material, said preparing station being configured for placing on the sheet fibrous material a treatment composition comprising at least one of a treatment liquid and a treatment foam, - a printing station, placed downstream of the preparing station, adapted to digitally ink-print at least part of a second side of the sheet fibrous material opposite the first side placed on the operative tract, the printing station comprising a printing module which, during said predetermined operative condition, is configured for: o defining a print on all a width of the sheet fibrous material, said width being measured normal to the advancement direction, o staying in a fixed position and printing the second side of the sheet fibrous material sliding on the operative tract, characterized in that the preparing station is configured for placing, on the sheet fibrous material sliding on the operative tract of the conveyor belt, a predetermined quantity of the treatment composition, said quantity of the treatment composition being selected so that the sheet fibrous material itself exhibits a weight percentage per square meter variation, between a section immediately upstream and a section immediately downstream the preparing station, comprised between 10% and 50%. o defining a print on all a width of the sheet fibrous material, said width being measured normal to the advancement direction, o staying in a fixed position and printing the second side of the sheet fibrous material sliding on the operative tract,