How repetitive integrated weed management strategies affect weed dynamics in organic crop rotation system

Abstract Integrated weed management (IWM) is essential for organic farming cultivation. However, an increased weed presence has been found on a farm that applies crop rotations, certified seed, high seeding rate, and false seedbed. This study aimed to evaluate the effect of false seedbed versus conventional tillage on weed dynamics on the field bean crop ( Vicia faba L. ‘Minor’) after 3 yr of application of crop rotation (field bean, sunflower [ Helianthus annuus L.], and durum wheat [ Triticum durum L.]) and IWM strategies. The field bean 2024 false seedbed (FB24Fs) yield was 0.9 Mg ha −1 , less than half of the field bean 2024 conventional (FB24C) yield (2 Mg ha −1 ). About 66% of total aboveground biomass (AGBt) was related to wild oat ( Avena fatua L.) in FB24Fs at harvest. The yield and AGB results at harvest can be explained by the evolution of crop and weed density dynamics. For FB24Fs, the crop plant number (PNc) at germination (G) was 30 m −2 , the weed plant number density (PNw) at G was 74% of the total (PNt), with predominance of monocotyledons, PNm (62%). The delay in crop seeding, germination, and environmental and soil differences affected early weed germination and high weed competitiveness. Employing repetitive cultivation strategies, such as false seedbed and late sowing, can lead over time to the selection of a few competitive weeds.