Corn (Zea mays L.), for silage, is very important in animal feeding because winter seasonal conditions last longer in Eastern Turkey. Corn yield components were investigated in plots, in which herbicide had been applied and also not applied at different irrigation levels in this study. The study lasted for two years and soil-water content was kept at five different levels [96% (I-1), 63% (I-2), 32% (I-3), 15% (I-4) and 4% (I-5)]. The species and intensities of the weeds at the irrigation levels were determined in the study. Plant length, green and dry herbage yields, leaf, stem and ear ratios were studied as criteria for corn yield. At the same irrigation levels, higher efficiency values were determined according to non applied plots in the atrazine applied plots. In both years, the lowest green herbage and dry herbage yields were determined at I-4 and I-5 irrigation levels. The weeds that are mostly seen on the plots, in which atrazine had not been applied are Alopecurus myosuroides Huds. and Sinapis arvensis L, respectively. Similarly, for both years, high densities of weeds were observed in the highly moisturized lands. The atrazine activities increased at the I-1 and I-2 irrigation levels in which water content of the soil is high.