Integrated effects of nitrogen form, row spacing, and herbicide treatment on maize

Abstract

To control weeds and cultivate maize (Zea mays L.) with higher yields, production systems have to include more efficient forms of N and appropriate herbicide treatments. The timing of N release could give maize an advantage over weeds in competition for resources, whereas cultivation at lower row spacing often decreases weed biomass. Knowledge about the different factors affecting herbicide efficiency increases the accuracy and reliability of chemical control. This study tested the weed infestation level and the development and productivity of a recently developed maize hybrid grown with the application of several integrated practices. The maize hybrid was sown with application of standard and slow-releasing urea, with row spacing of 50 and 70 cm and treatment with either a pre-emergence or a post-emergence mix of herbicides. The numbers of plants of each weed species and their biomass were lower after the application of herbicides, although N form and row spacing produced no significant differences in the average weed infestation level for 3 yr. The post-emergence herbicide treatment was more effective than the pre-emergence treatment for weed biomass reduction and enhancing maize yield parameters. The N form did not influence any measured yield parameter, whereas the 70-cm row spacing resulted in significantly higher harvest index and grain yield (0.45 and 9.19 Mg ha−1, respectively) than the 50-cm spacing (0.43 and 7.36 Mg ha−1, respectively). The wider row spacing resulted in higher grain yield through its interaction with N form and herbicide treatment.