Starter fertilizer impact on corn seedling emergence and grain yield uniformity

Abstract Increasing grain yield is often associated with a uniform plant stand and crop development. The use of starter fertilizer, especially when corn ( Zea mays L.) is planted early, can promote more uniform crop development. This study aimed to (i) investigate the impact of starter fertilizer placement on corn seedling emergence, (ii) assess whether the timing of seedling emergence influences corn developmental stages and per‐plant grain yield, and (iii) identify the most critical factors contributing to grain yield outcomes. Field trials were conducted in 2022 and 2023 near Brookings, SD, comparing early and normal planting dates with different starter fertilizer placements and rates. The fertilizers were placed in the seed furrow at a lower (IFL) and a higher (IFH) rate; 5 × 5 normal rate placement (5 × 5); a combination of IFL and 5 × 5 placement (combo); and a control without starter fertilizer application and provided approximately 10, 15, 25, 35, and 0 kg P 2 O 5 ha −1 , respectively. Starter fertilizer placement had minimal influence on corn seedling emergence across the planting dates. Late‐emerging plants showed delays in growth, silk and tassel emergence, ear weight, and grain yield. However, emergence timing was not the most critical factor influencing final yield. Instead, silk emergence timing, final plant height, and plant spacing were the most influential factors in determining grain yield, with R 2 values ranging from 0.470 to 0.679. Therefore, targeting uniform reproductive development and plant spacing may offer more effective strategies for improving corn grain yield outcomes rather than solely focusing on early plant emergence.