Abstract: The direct-injection spraying device, in particular for an agricultural vehicle, according to the invention comprises: a main tank (C), at least one spray boom (R), a circuit connecting said tank (C) to said boom (R), said circuit comprising a main pump (PP) and a bypass (d) for controlling the flow rate in said boom (R) in accordance with the traveling speed of said vehicle, at least one active substance store (m1, m2, m3) connected to said circuit by a metering pump (P1, P2, P3). This device comprises a cyclone mixer (M) capable of receiving, as input, the liquid (E1) from said main tank (C), and the pressurized liquids coming from said active substance store (m1, m2, m3), and capable of eliminating said boom (R) as output.