Evaluation of urea starter fertilizer effects on weed interference in cotton (Gossypium hirsutum L.) cultivation

A filed experiment was conducted to determine the effects of urea starter fertilizer and post emergence herbicide effects on weed interference in early season cotton production and some agronomic traits of cotton plants in Gorgan region (northeast Iran) in 2008. Experiment was carried out as factorial based on a randomized complete block design with four replications. First factor was weed management at four levels including early post emergence application of Methazole + Envoc in early cotton growth, late post emergence application of Methazole + Envoc in 15-20 cm cotton plant height period, early hand weeding and late hand weeding in cotton growth season, and four levels of starter fertilizer as the second factor were 0, 50, 100 and 150 percent of recommended dosage of urea starter fertilizer (175 kg.ha-1), respectively. Planted cotton cultivar was Siokra, one of commercial verities in Golestan province. Late hand weeding and late herbicide application resulted in the highest amounts of whole weed biomass 10 day after weed control (W1) and a month after weed control (W2). Increasing urea starter fertilizer level increased weed biomass 10 day after weed control, but decreased it a month after weed control.