Weed control and grain yield response to nitrogen management and herbicides

In order to investigate the effect of herbicides application and nitrogen (N) levels on weed control and grain yield of corn, two field experiments were conducted in 2007 and 2008. The treatments consisted of four levels of 50, 100, 150, and 200 kg N P ha-1 as main plots and herbicides including atrazine plus alachlor at 1+2.44 and 1.92+1.5, 2, 4-D plus MCPA at 0.36+0.31 and 0.54+0.46, rimsulfuron at 0.02 and 0.04 and foramsulfuron at 0.03 and 0.06 kg a.i. P ha-1 were the sub factors. A weed-free and a weedy check were also included. The results revealed that increased levels of applied nitrogen tended to enhance the total weed biomass significantly. Foramsulfuron controlled field bindweed (Convolvulus arvensis L.) effectively in both years. Redroot pigweed (Amaranthus retroflexus L.) was satisfactorily controlled by foramsulfuron in both years. Rimsulfuron and 2,4-D plus MCPA had the highest redroot pigweed dry weight and controlled chinese-lantern-plant (Physalis alkekengii L.) less effectively compared with field bindweed and redroot pigweed. Addition of N increased the competitive ability of corn against weeds and resulted in higher grain yield. Foramsulfuron controlled weeds effectively and caused significant increase in corn grain yield between 44 and 66% higher than weedy check in both years