Winter straw cereals are crops with low nitrogen trapping capacity in the fall. The implantation of frost-sensitive and uncompetitive "nitrogen catching" species (buckwheat, mustard, etc.) mixed with winter straw cereals makes it possible to extract some of the available nitrogen without limiting the development of the winter cereal (needs are limited during this period). The frost-sensitive accompanying plant will disappear during the winter.
The sowing of the accompanying cover can be carried out simultaneously with that of the cash crop (seeding machine with separate hoppers) or before it (thrown sowing of the nitrate trap species followed by the sowing in lines of the cash crop) .
If the canopy is established early (before early September), this technique corresponds to the establishment of an intermediate crop before the winter cereal and the "no-till" sowing of this cereal in the canopy that will be destroyed post sowing by the frost (a rolling in December -January being always possible to facilitate this destruction of the canopy).