Interactive Effects of Nitrogen and Phosphorus Fertilizer Sources and Weedicide Application with Foliar Urea/CAN on Root Development and Grain Yield of Maize

Abstract

Maize (Zea mays L.) is a major cereal crop with diverse uses in food, feed, and industry, yet its productivity is severely constrained by weed infestation. Weeds compete with maize for nutrients, water, and light, reducing growth and yield, while herbicides, though effective, can impose stress on the crop. Therefore, synchronizing fertilizer application with weedicide use is essential to minimize crop stress and maximize productivity. A field experiment was conducted at the Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, using a randomized complete block design to assess the interactive effects of nitrogen (N) and phosphorus (P) fertilizer sources, weedicide application timing, and foliar N sprays on maize growth and yield. Fertilizer rates were 175, 125, and 125 kg ha⁻¹ of N, P, and K, respectively, applied as urea + diammonium phosphate (DAP) or calcium ammonium nitrate (CAN) + nitrophos (NP). Weedicide ‘Metolachlor’ (1 L acre⁻¹) was applied either four days before or after the second N split, combined with a 0.5% foliar spray from the respective N source. Growth and yield attributes, including plant height, cob traits, biological yield, and root development, were recorded at maturity. The treatment involving CAN + NP, with weedicide applied after the second CAN split and supplemented by 0.5% foliar N as CAN, produced the best results, with increases of 4.73% in plant height, 31% in grain yield, 25.97% in biological yield, and 14.21% in root weight compared to urea + DAP with weedicide applied after urea. These findings highlight that integrating CAN + NP fertilization with timely weedicide application and foliar feeding enhances nutrient uptake, reduces herbicide stress, and significantly improves maize productivity.