Evaluating the impact of biostimulants at variable nitrogen rates in corn production

Biostimulants have garnered significant interest due to their potential to enhance crop productivity while optimizing nitrogen (N) uptake and nitrogen use efficiency (NUE). However, field research testing their efficacy in corn (Zea mays. L) production remains largely unexplored. Therefore, a field study was conducted in 2022 and 2023 in Mississippi (MS). A split plot design was implemented, with N rates as the main plot including 0 (control), 90, 180, 269 kg N ha⁻¹ at Starkville, while Stoneville included an additional rate of 224 kg N ha⁻¹. The subplot consisted of seven treatments, including a no biostimulant (check) and six microbial biostimulants (Source Corn®, Envita®, iNvigorate®, Blue N®, Micro AZ™, and Bio level phosN®) applied either as foliar at V4-V5 growth stages or in-furrow at planting. Nitrogen rates positively affected grain yield at all three site-years, whereas biostimulants effects on grain yield were only observed at one site (Stoneville 2022). Moreover, these differences only existed between six biostimulants and they were not significantly different from check plot with no biostimulant. Higher N rates reduced the efficiency of grain production in terms of NUE parameters and N uptake, showing a consistent inverse trend across all site years. This study observed minimal synergistic benefits of microbial biostimulants, despite evaluating their effectiveness alongside varied N rates. Further research testing diverse biostimulant categories with varied dosages and application timings is warranted to confirm their potential benefits for higher productivity and agricultural sustainability.