Investigation of the Damage Caused by Weeds Competing with Maize for Nutrients

The experiment was set up on a trial site where the weed infestation was already known. The objective of this study was to achieve efficient weed control. The effect of herbicide treatments on biomass production and nutrient uptake of weeds were determined and the impact on corn yield was measured. Effect of the maize-weed competition on the biomass and yield production of maize was tested in 2005 at Keszthely, Hungary. A randomized small plot trial was carried out in three replications on Eutric cambisol soil. The effect of the herbicide treatment was compared to the untreated plot. The tested herbicide was Trophy at 3 l fp ha-1 (active ingredient [a.i.] acetochlor + dichlormid) in a tank mix combination with Merlin at 0.12 kg fp ha-1 (a.i. isoxaflutole), which provided excellent weed control. The product's efficacy was evaluated by estimating the percentage of weed cover in 1 m2. Individual weed species were identified, and the efficacy was evaluated by species. The fresh and dry weights of weeds and maize were measured, along with the effect of the weeds on the growth of maize and on the yield. The percentage of weed coverage in the untreated plot was 9.6% at the first (3 June) and 28% at the second (4 July) evaluation. The weed coverage in the treated plot was 0.5% at the first and 0.6% at the second evaluation. The fresh and dry shoot weights were measured on 27 July, and both the fresh and dry weights of the crop were reduced by 25 and 55%, respectively, in the untreated plots in comparison to the treated ones. The fresh and dry weights of cobs were reduced by 47% and 56% in the untreated plots. The herbicide treatment provided good weed control and provided favorable conditions for the crop. As a consequence, the fresh and dry weights of maize were 1.9 and 2.3 times higher in the treated plots than in the untreated ones. Nutrient concentration of maize was measured as well, to estimate the proportion of nutrient uptake by different plant species and the competition for nutrients between maize and weeds. The effect of the competition of weeds was that there were 1.9-2.3 times fewer corncobs on the control plots. There was strong competition between weeds and corn for nutrients. On the weedy control plots, weeds contained 16 kg ha-1 nitrogen (N), 2.5 kg ha-1 phosphorus (P), and 28.2 kg ha-1 potassium (K), whereas corn contained 38.2 kg ha-1 N, 4.2 kg ha-1 P, and 29.5 kg ha-1 K.