Abstract: A distribution device for a single-seed seed drill, comprises a rotatable plate 5 having a peripheral rim 6 and a substantially vertical axis of rotation. The rim 6 has recesses 9 substantially parallel to the axis of rotation and regularly spaced angularly about a circle 10 of the rim, the horizontal section of these recesses and the thickness of the rim corresponding substantially to the size of a seed. The recesses move above a fixed rim 11 in which are provided, directly below the recesses 9 of the rotatable plate, openings 13 for communication with a transport device 14 which leads to a seed drill. A barrier 22, 22' upstream of each opening 13 in the fixed plate, is provided to retain seeds not engaged in the recesses of the rotatable plate. A brake 18, 39 or 52 for the outflow of seeds is interposed between the central portion of the rotatable plate onto which the seeds are fed, and the barrier 22, 23 or 50.

Abstract: A grain drill having a plurality of closely spaced seeding units is modified to change the pattern of seed flow through one of the seeding units cyclically within the length of a row, so that when the plants emerge, the one row will be visibly different from the other rows. The visibly different row can then be used as a marker for weed control spraying or the like.