Fig. 4. Average fall seedbank density (± standard error) of all weed species in zero- and conventional tillage systems within six crop rotations at Indian Head, SK, from 1992–1996. Rotations (R) 1 through 3 were wheat–canola–wheat–lentil, where R1 (Conv 1) had conventional input levels with only postemergence herbicides, R2 (Conv 2) was similar but with pre-emergence trifluralin in canola and lentil, and R3 (Reduced Input 1) was similar to R2 but with reduced herbicide inputs (no grassy weed herbicides in wheat). Rotation 4 (Reduced Input 2) was also low input wheat–pea–wheat–lentil with a similar reduced herbicide strategy as R3 and 50% reduced fertilizer usage in wheat. Rotation 5 (Diversified 1) was conventional input and diversified canaryseed–sunflower–wheat–lentil, and R6 (Diversified 2) was conventional input diversified wheat–tame mustard–canaryseed–lentil.
