Response of a weed community to nitrogen fertilization: a multivariate analysis

Abstract The effect of nitrogen fertilizers on the composition of a weed community was investigated in a barley field. Two doses (70 and 140 kg N/ha) of three fertilizers (ammonium sulphate, calcium‐ammonium nitrate, and liquid urea) were used. The results were evaluated using the canonical correspondence analysis. Hybrid analyses and various combinations of environmental variables and co variables were used to separate the influence of the dose and the type of fertilizer and to separate the direct and indirect effects of fertilization. The results reveal that both the dose and type of fertilizer have a significant effect on the composition of the weed community. The results suggest that both the direct effect of fertilizer and an indirect effect, through increased competition of the crop, are important determinants of weed community composition.