Özet:

The heights, biomass, and shares in total biomass of one corn and one weed planted at the same time were determined in the pot studies which the effects of different nitrogen doses (0, 120, 240 and 480 kg/ha) given in two periods on the competition of corn with barnyard grass (Echinochloa crus-galli), Johnsongrass (Sorghum halepense), jimsonweed (Datura stramonium) or common purslane (Portulaca oleracea) were evaluated. It has been determined that nitrogen applications contributed to the heights of corn, common purslane and jimsonweed and there has been no difference in the length and biomass of Johnsongrass and barnyard grass. While variable results were obtained in biomass of common purslane, it was observed that increasing nitrogen doses increased the biomass of the jimsonweed and its share from the total biomass. Corn benefited more from nitrogen in competition with weeds other than jimsonweed or was not affected by increased nitrogen doses. It has been concluded that increasing densities of jimsonweed will provide superiority to corn in nitrogen competition and therefore, its management should be given importance. Since nitrogen is a mobile element, it is recommended to prefer to methods such as strip fertilization and fertigation in order to make corn advantageous in competition with weeds.