Weed seed bank dynamics under various rotations and field production resources

Weed seed bank dynamics in corn, sugar beet and wheat plots in rotation with wheat were studied under conventional and ecological management systems during 2 years. The experiment was laid out in a split- plot design in a randomized complete block, where 3 crop rotations were assigned to main plots and 5 cropping systems including high–input, medium–input, low–input, integrated and organic systems were allocated to subplots. The results showed that crop species and weed management practices in different cropping systems significantly affected weed seed bank composition. However, weed seed bank dynamics were indirectly affected by crop rotation. The highest mean weed seed density and weed species diversity in soil surface layer was observed in organic system while high–input system had the lowest seed density. Weed seed density of soil surface layer in organic and low–input systems were twice of that in deeper soil layer. However, in high–input system weed seed bank was uniformly distributed over soil layers. The highest weed seed density was observed in continuous wheat plots where seeds were mainly accumulated at soil surface layer. Corn-wheat and sugar beet-wheat rotations led to a lower seed bank density and more uniform distribution of weed seeds in soil.