Abstract: The invention concerns a device for the selective metering of seed intended essentially for sowing and/or reseeding soils and of additives intended essentially for improving and/or treating the soils; said device comprising essentially: a) a hopper (1) intended to contain the seed or the said additives; b) a unit for the selective metering (2, 3, 4) of the seed or of the additives originating from the said hopper; c) a mechanism (5, 6) for transferring the seed or the additives originating from the metering unit, into furrows created in the soil by means of a scarification unit provided with a plurality of discs (7); wherein the unit for the selective metering of the seed and additives originating from the hopper comprises in combination: a) a selective metering roll (2) comprising, longitudinally, a plurality of successive zones (Z) each subdivided into at least two zones (Z1) and (Z2) provided with means (2A), (2B) and (2C) suitable for metering the seed or the additives according to their particle siz