Weed seed bank response during the early conversion period to less intensive tillage systems

In recent decades, adoption of less intensive soil tillage practices has increased due to numerous environmental and economic benefits. Our investigation was performed during 2020-2022 and examined germinable and persistent weed seed bank response in the early conversion period from conventional (CN) to conservation (CS) and no-tillage (NT) system under the humid, temperate climate of central Europe. The germinable seed bank determined in the spring cropping period was up to four times greater compared to the autumn cropping period. By using NT, consistently lower germinable weed seed banks were seen compared to CN or CS with observed reductions of weed seed density 45-75%. Final abundance of persistent weed seed bank (117,000 seeds m-2) was considerably greater than average size of germinable weed seed bank across years (27,000 seeds m-2). The vertical distribution of germinable weed seed bank in the soil did not differ between the tillage treatments, while using CS and CN more persistent weed seeds were accumulated in the intermediate (5-10 cm) or the bottom (10-20 cm) soil layer. CS and NT facilitated greater weed species diversity and evenness in both germinable and the persistent weed seed bank. Our results showed that introduction of different tillage systems had an almost immediate response in the size of germinable weed seed bank in the soil. Thus, when converting new fields to alternative tillage systems with high weed pressure, weed seed bank studies are advocated to select systems that reduce germinable seed in the seedbank. This method will enable coherent integration of non-chemical weed management strategies and support existing IWM methods in transition to sustainable agroecological based weed management strategies.