Modelling the interaction of urea fertilizer and herbicide doses on wheat yield in competition with weed

Understanding the interaction between crop-weed competition and herbicide doses may, in many cases, result in a recommendation to reduce the consumption of the herbicide, which is both environmentally and economically important. Nitrogen fertilizer also influences the competitive balance through changes in weed density and biomass, and also contributes to environmental pollution. Hence, the evaluation of the interaction of herbicide doses and nitrogen fertilizer application is necessary for proper management of weeds and achieving acceptable economic yield along with minimizing environmental negative impacts. In order to modelling wheat–Sinapis arvensis L. and Avena ludoviciana Durieu competition in response to urea and herbicide doses Othello OD, a field experiment was conducted as split plots in a randomized complete block design with four replications at Agricultural Sciences and Natural Resources University of Khuzestan. Urea fertilizer included five levels of 0, 45, 90, 180 and 330 kg/ha of urea was considered as the main plot and the herbicide dose of “Othello OD” in six levels of 0, 0.32, 0.64, 0.96, 1.28 and 1.6 l/ha (recommended dose 1.6 l/ha) was considered as the sub-plot. Based on the combined model, the dosage required for reducing the weed biomass to less than 150 g/m2 with consuming of 0, 45, 90, 180, 250 and 330 kg/ha of urea fertilizer was predicted to be 0.64, 1.04, 1.12, 0.96, 0.88 and 0.80 l/ha, respectively. Also, with application of 330 kg urea fertilizer with 0.32, 0.64, 0.96, 1.28 and 1.6 l/ha of herbicide, wheat grain yield respectively, 298.58, 450.62, 585.74, 654.35 and 675.58 g/m2, receipt. The lowest number of weed seeds was obtained in 1523.58 with 330 kg/ha urea fertilizer with 1.6 l/ha of herbicide dose.