INTEGRATION OF NITROGEN FERTILIZER AND HERBICIDES FOR EFFICIENT WEED MANAGEMENT IN MAIZE CROP

Investigating the response of maize plants to nitrogen levels and herbicides, a field trial was undertaken in 2006 at the Malakandher Research Farm, Agricultural, University Peshawar, Pakistan. The trial was carried out under randomized complete block design with split plot arrangements and each treatment having four replications. Three levels of nitrogen (N) fertilizer in urea form (viz. 80, 120 and 160 kg ha^-1) and three herbicides (viz. Stomp 330 EC, Atrazine 38 SC and 2,4-D ester) were applied in the trial. A control plot was maintained with each treatment for comparison. The N levels were assigned to the main plots and the herbicides were assigned to the sub plots. For all the N levels, their half N dose was applied after 10 days of seed germination while the second half N dose was applied after 45 days of the crop germination. Stomp 330 EC @ 0.75 and Atrazine 38 SC @ 1.00 kg ha^-1 (both applied as pre-emergent) at the time of sowing and 2,4-D (ester) @ 0.80 kg ha^-1 was applied as post emergent after 25 days of sowing the crop. Results have shown the lowest weed density (30.83 weeds m-2) and the lowest dry weed biomass (6.80 g m^-2) in plots that were sprayed with atrazine while the highest weed density (54.33 weeds m-2) and the highest dry weed biomass (10.83g m^-2) was found in control plots. In case of plant height, herbicides did not significantly affect the maize plant height; however, the N levels had significantly affected the maize plant height and the tallest plants were recorded under 120 and 150 kg ha^-1 N levels (i.e. 164.8 and 163.5 cm, respectively) followed by 90 kg ha^-1 N level (161.3 cm). The shortest plants of maize were found in the control plots. The maximum cob length (12.33 cm) was recorded in the stomp and in the atrazine treated plots while the minimum cob length (9.83 cm) was found in the control plots. Maize gave the greatest grain yield (1.47 t ha^-1) in the atrazine treated plots and the lowest grain yield (1.24 t ha^-1) was realized in the control. In addition, the greatest grain yield of maize (1.5 t ha^-1) was found under the 160 kg ha^-1 N level. The interaction of all the herbicides with 160 kg ha^-1 N level had produced the best grain yield of maize. As over all, atrazine was found to be the best herbicide for weed control in maize and the 160 kg ha^-1 N level was found to be the best for increasing productivity of the crop.