Elytrigia repens population dynamics under different management schemes in organic cropping systems on coarse sand

Summary in the original language of the document

Elytrigia repens is a rhizomatous perennial weed prevalent in organic cropping systems in Scandinavia. This study analysed the population dynamics of E. repens in a long-term crop rotation experiment on coarse sand in Denmark in order to gain insights into the factors influencing its population changes, especially those important for outbreaks of E. repens infestations. Data were obtained from three cycles of four-year crop rotations with various cash crops and annual grass-clover subjected to four treatment combinations: with and without animal manure and with and without catch crops. E. repens was controlled by different tillage and mowing strategies between and within crops. Pulses and spring cereals caused the highest population increases, especially when preceded by grass-clover. Potatoes grown in ridges and winter rye suppressed the E. repens population, but tillage between crops was necessary to decrease the population. Manuring generally reduced E. repens growth by 28%. Thus there are crops that need particular attention when designing crop sequences, provision of sufficient nutrients is important to strengthen crop suppression of weeds, and mechanical interventions are needed to manage E. repens satisfactorily.