Corn response to multiple rates of nitrogen and sulfur

Sulfur (S) deficiency has been increasing due to decreased natural deposition in the United States (US), highlighting the need to integrate S with nitrogen (N) in corn (Zea mays) nutrient management. Herein, we assessed corn response to various N and S rates and examined the impact of N, S, and N × S on i) grain yield, N/S agronomic efficiency (NAE/SAE), and N/S partial factor productivity (NPFP/SPFP), ii) N/S uptake in leaf (NLF/SLF) and grain (NGR/SGR), and iii) growth parameters. Field experiments were conducted at four site-years in 2021 and 2023 at Starkville, Brooksville, and Stoneville, within the Mississippi (MS) using a randomized complete block design with four replications. Treatments included 0, 112, 224, and 336 kg N ha−1 and 0, 22, 44, and 66 kg S ha−1, and their interactions. The key findings of the study were i) N × S interaction affected SAE and SPFP at all site-years, NPFP at 50 % site-years, and NLF, ear height at 25 % site-year, ii) N-only treatments influenced grain yield, NAE, NGR at all site-years, NLF and SLF at 75 % site-years, and NPFP, plant and ear height, stalk diameter, leaf area index (LAI), and SGR, at 50 % site-years, iii) S only treatments influenced grain yield, NAE, NGR, and SLF at 25 % site-year. Although, the response of S was less frequent in all the tested parameters, current findings indicated the vitality of S fertility for all parameters except growth parameters. Moreover, considering all site-years, the agronomic optimum N rate (AONR) ranged between 208 and 344 kg ha−1. In summary, the response of each tested parameter, including AONR, was highly site-specific. This underscores the critical importance of considering local factors while developing nutrient recommendations. Moreover, an opportunity exists for achieving optimal agricultural outcomes and sustainability by tailoring nutrient management practices to specific sites.