A placing unit for a seed drill includes at least two furrow-opening disks and at least two devices for delivery of particulate products from at least one reservoir, the respective ejection outlets of which are situated between the two opener disks in a manner mutually offset along the direction of advance. The placing unit also includes a body carrying the disks and devices. The placing unit includes an elongated assembly for firming of the product or products deposited at the bottom of the furrow, and an interface for linking with the body for the seed-firming assembly, which includes an end for fixation with the interface and an opposite bracing end. The linking interface includes at least two fixation sites for the corresponding end of the assembly, offset longitudinally relative to one another along the direction of advance.
