Application performance and nutrient stoichiometric variation of ecological ditch systems in treating non-point source pollutants from paddy fields

•Traditional concrete ditch was converted for removing NPS from paddy fields.•Higher removals of TOC, TN and TP were obtained in the converted ecological ditch.•All ecological ditch types had capacities to remove nutrients in simulated runoff.•Eh had a relatively stable condition for plants to maintain biological homeostasis.•Stoichiometric characteristics (water, sediment and plants) relate to nutrient removal.