This NebGuide discusses weed seed entry and loss from the soil, and provides examples of the density and diversity of the soil weed seed population.
Most weeds owe their beginning to seed in the soil.
The soil acts as a seed storage reservoir and a growth medium for weedy plants. The kind or species and numbers of seed in the soil is closely linked to the cropping history of the land. Grasslands that have been cultivated and then reseeded to grasses generally contain mixed weed populations. When grassland is cultivated, the seed in the soil changes rapidly. The number of seed in the soil is variable and may range from 2 seeds per pound of surface soil in grassland to 140 seeds per pound of surface soil in cropland.