As with any weed management method, distinguishing between the crop and the weed is of utmost importance. The more similar the weed is to the crop, the more difficult it will be to control. Seed decline in seedbanks is increases with the frequency of tillage. Frequent tillage has selected for annuals and to some extent, perennials that rely on fragmentation and dispersal for propagation.
Deep tillage tends to select for species with dormant, long-lived seed.
The primary means by which weed seed moves throughout the vertical soil profile is by means of tillage operations. For many species, however, the seeds are dropped very near the maternal plant resulting in a clumped distribution for the future population if left undisturbed. Tillage tends to disperse these clumps more evenly across the field. Seed distribution along the vertical soil profile is more uniform under a moldboard plow tillage system than under chisel plow, disk, or no-till systems. But with prolific seed producers, weeds may have produced 40 million seeds or nutsedge tubers to an acre.