Long-term effects of crop rotation and fertilizers on weed community in spring barley

Integrated weed management programs require a clear understanding of the mechanisms influencing the establishment, growth, and reproduction of unwanted plants (weeds) in agro-ecosystems. This study evaluates the effect of long-term (95 years after the establishment of the site) crop rotation and chemical fertilizers on the weed community dynamics in spring barley at the Agricultural University of Timiriazev, Agricultural Site in Moscow. The weed community occurring on plots of spring barley (grown in crop rotation or continuous) was examined under nitrogen, potassium, phosphorus, NPK, and a control with no fertilizer treatments. Statistical analyses were conducted using analysis of variance (ANOVA) and principal component analysis (PCA). The results show that a) at the study sites, spring weeds are dominant components on agro-ecosystems; b) weed density, particularly of perennials, has significantly decreased under crop rotation; c) the combination of fertilizers (NPK) also decreased the weed density, d) weed density under separate N, P, and K applications was almost the same as that in the control plots. These results suggest that long-term crop rotation and NPK application can strongly affect and reduce weed density in spring barley.