Stakeholder need: nitrogen, food, and environment

Nitrogen (N) fertilizer has been one of the most transformative inputs in human history. Since the development of the Haber–Bosch process, synthetic N has enabled a massive expansion of food production, supporting population growth and global economic development. It is estimated that nearly 40% of the global population would not be alive today without synthetic fertilizer (Smil, 2001a), and approximately half of current global food production depends on it (Smil, 2001b, 2011). In the United States, corn production dominates fertilizer N use; more N fertilizer is applied to corn than to all other crops combined (Simons et al., 2014). Corn serves not only as a staple crop for food and livestock feed but also as a critical feedstock for renewable fuels and industrial products, making it central to agricultural profitability and national food and energy security.

Stakeholders, including farmers, agribusiness, crop consultants, policymakers, and conservation groups, consistently identify efficient N management in corn-based cropping systems as a top priority (Houlton et al., 2013). Nitrogen fertilizer is an expensive input, usually second only to seed in corn production. At present, producers face tremendous uncertainty in making N fertilizer decisions. Weather variability, soil type, organic matter levels, crop rotation history, and manure applications all influence how much N is available to crops and how much is lost through leaching, denitrification, or volatilization (Sierra, 1997; Fernández et al., 2017; Yi et al., 2023; Li et al., 2024; Liao et al., 2024). Fertilizer must be applied well before the period of peak crop demand, and the inherent unpredictability of in-season rainfall and mineralization creates pressure to over-apply fertilizer as “insurance” against yield loss. This strategy often reduces profitability and increases environmental damage (Hong et al., 2007; Shcherbak et al., 2014; Miller et al., 2020; Lu et al., 2022).

Producers, commodity groups, and conservation organizations are calling for more precise N management recommendations and decision tools that account for spatial and temporal variability in soil N supply and crop demand. For example, in 2023, 30 farmers, crop advisors, scientists and other agricultural stakeholders in Iowa attended a three-day event to design a new tool to support N fertilizer rate decisions. Stakeholders seek guidance that integrates diverse N sources, including animal manures, green manures, and cover crops, while also leveraging modern innovations such as enhanced efficiency fertilizers, remote sensing, and precision agriculture technologies (Morris et al., 2018). Without continued research and coordinated multi-state efforts, inefficiencies in N use will persist, undermining farm profitability, degrading water quality, and contributing to agricultural nitrogenous emissions.

The proposed NC1195 renewal aligns closely with the USDA Science and Research priorities released in December 2025, particularly the goals of increasing profitability of farmers and ranchers and promoting soil health to regenerate long term productivity of agricultural lands. By improving nitrogen use efficiency through precision management, soil health based approaches, and advanced decision support tools, this project seeks to reduce input costs, enhance producer profitability, improve resilience of corn based systems, and minimize environmental nutrient losses across the Corn Belt.

Importance of improving N use in the U.S.

The paradox of N fertilizer is that it is simultaneously indispensable for food security and one of the most problematic environmental pollutants. Nitrogen is an essential input for sustaining crop yields in intensive systems; without it, U.S. agriculture could not meet the demand for feed, food, and fuel derived from corn-based systems. Yet the unintended consequences of N use are among the greatest environmental challenges facing agriculture (Aneja et al., 2009; Sutton et al., 2011a). Excess nitrate leaching contaminates groundwater and surface water, increasing health risks and water treatment costs (Houlton et al., 2019). Drainage from the Corn Belt contributes heavily to hypoxia in the Gulf of Mexico and other coastal systems, where algal blooms and oxygen depletion harm aquatic life and reduce fisheries productivity (Burkart and James, 1999; Rabalaiset al., 2002; Conley et al., 2011; Guo et al., 2020). In the atmosphere, agriculture is now the single largest source of nitrous oxide (N₂O), a radiatively active gas with ~300 times the heat-trapping capacity of carbon dioxide and the leading ozone-depleting emission of the 21st century (Davidson, 2009; Ravishankara et al., 2009; USEPA, 2021; Lu et al., 2022).

In addition, ammonia and nitrogen oxides released from agricultural systems contribute to the formation of secondary particulate matter, a major component of PM_2.5 pollution with well-documented impacts on air quality and human respiratory health (Warneck, 1999; Baek et al., 2004; Aneja et al., 2009). Reactive N deposition further exacerbates environmental stress through regional haze, reduced visibility, and ecosystem acidification, linking agricultural N losses directly to widespread air quality and ecological concerns (Sutton et al., 2009; Sutton et al., 2011b).

If progress is not made, the consequences are clear: stagnating N use efficiency (NUE), uncompetitive farm profitability, and escalating environmental costs borne by farmers, communities, and ecosystems (Sutton et al., 2011a). Such outcomes are unsustainable and will likely lead to more stringent regulation of nutrient inputs, increasing production costs and constraining management flexibility. Conversely, the potential benefits of advancing N management are substantial. Research demonstrates that improved understanding of soil N mineralization, better accounting for cover crop effects, and more precise fertilizer timing can sustain or even increase yields while reducing nutrient losses (Scharf et al., 2006b; Shapiro and Wortmann, 2006; McDaniel et al., 2020). Thus, improved N management offers one of the most effective avenues for agriculture to simultaneously enhance economic returns and reduce its environmental footprint.

Weather uncertainty further heightens the urgency of improving N use in the U.S. In the Corn Belt, overall precipitation is projected to rise modestly, but with a disproportionate increase in the frequency and intensity of extreme rainfall events during spring and early summer (Kellner and Niyogi, 2015). These shifts accelerate N losses through leaching and denitrification and contribute to downstream nitrogenous emissions in aquatic systems (Bowles et al., 2018). Greater weather variability also increases the unpredictability of soil N mineralization, complicating recommendations and reducing the reliability of traditional management strategies (Yi et al., 2023). Without adaptation, producers face heightened risks of yield loss, increased environmental impacts, and intensified regulatory scrutiny.

Technical feasibility: current knowledge of N-cycle processes and their management

This research is technically feasible due to recent advances in agronomy, soil science, microbiology, and precision agriculture, combined with the demonstrated capacity of NC1195 members to execute large, multi-state projects. While the fundamental biological underpinnings of the N cycle are well described, major gaps remain in quantifying and predicting how these processes interact under real-world field conditions. For example, soil organic matter and manure mineralization can supply a substantial fraction of crop N needs, but the timing and magnitude of this release vary with temperature, moisture, oxygen, and management history  (Sierra, 1997; Lynch, 2013; Yan et al., 2020; Klein et al., 2025). Overlooking these dynamics often leads to over-application of fertilizer N. In addition, fertilizer inputs themselves can stimulate soil organic N mineralization through “priming effects,” yet most recommendation systems do not account for this feedback (Jenkinson et al., 1985; Mahal et al., 2019; Haas et al., 2024).

Conservation practices present both opportunities and trade-offs. Cereal rye cover crops, for example, are effective at reducing nitrate leaching, but they can also increase N₂O emissions or depress subsequent corn yields if not carefully managed (Scharf and Alley, 1988; Mamo et al., 2003). Recent multi-state research led by NC1195 members demonstrates that yield drag of up to 10% or more can occur in corn following cereal rye, even when terminated two weeks before planting, highlighting the need for deeper understanding of these mechanisms (Preza-Fontes et al., 2022; Acharya et al., 2017). In addition, multi-state research led by NC1195 members estimated that corn following cereal rye needs an additional ~50 lb N/acre than corn following no cover crop or a legume cover crop (Rawal et al., in prep). Key unresolved questions include what regulates soil N-supplying power, whether cover crops improve or worsen the N₂O emission balance, and what factors drive the yield penalties often observed following cover crops. Addressing these questions requires integrated approaches that link soil health, microbial dynamics, and cropping system design. At the same time, new technologies offer unprecedented opportunities for precision management. Enhanced efficiency fertilizers, nitrification and urease inhibitors, and alternative N sources such as anaerobic digestate solids and processed manure products are increasingly being tested for their ability to improve NUE and reduce losses (Mirabilia et al., 2025; under review). Remote sensing tools, UAV platforms, and crop canopy sensors now enable real-time monitoring of crop N status across spatially variable landscapes (Ciampitti and Vyn, 2011). Biosensor-based diagnostics developed and deployed by NC1195 members have provided growers with real-time, spatially sensitive data to support adaptive management. These tools have already been integrated into on-farm research, extension programs, and training for farmers and crop advisors, demonstrating both feasibility and impact. Similarly, the Nitrogen Fertilizer Application Consultation Tool (NFACT), launched in 2025, provides over 21,000 scenario-specific estimates of optimum N rates using field trial data and calibrated crop models. Together, these innovations show that decision-support systems are maturing into practical tools for widespread adoption.

The NC1195 group has repeatedly demonstrated capacity to carry out this type of research and outreach. Past collaborations have clarified spatial variability in N response (Scharf et al., 2005; Scharf et al., 2006a; Scharf et al., 2006b; Laboski et al., 2008), changes in the economic optimum N rate over time (Baum et al. 2025), quantified interactions between fertilizer and manure (McDaniel et al., 2020), and advanced the science of soil health and its relationship to C and N cycling (Canisares et al., 2021; Studt et al., 2021; McDaniel and Middleton, 2024; Keiser et al., 2025). Ongoing work has shown how past management, such as repeated manure applications, alters root C allocation and stabilization (Keiser et al., 2025), and how perennializing systems or integrating livestock can improve soil health and reduce N losses (Carey et al., 2025; Moore et al., 2025; Yi et al., 2025). Collectively, the group members’ expertise in agronomy, soil microbiology, modeling, and extension, coupled with proven success in developing and deploying decision-support tools, demonstrates that the proposed research is both technically feasible and poised to deliver transformative outcomes for N management across the Corn Belt.

Advantages of a multistate effort: regional project goals

Nitrogen management challenges are not confined to any single state. The soils, climate, cropping systems, and manure management practices of the Corn Belt are diverse, and results from a single location rarely apply across the region. A multistate effort is therefore essential to develop recommendations and tools that are broadly relevant and widely adopted.

The NC1195 project has a strong record of leveraging regional collaboration to produce impactful outcomes. Multistate experiments and data syntheses have shown that the “optimal” N rate can vary not only between states but within fields, depending on soil properties and rainfall patterns (Mamo et al., 2003; Scharf et al., 2005). By pooling data across environments, the group members have produced recommendations that are more robust and defensible than those from isolated studies. The regional nature of this work ensures that findings are not skewed by local anomalies and that recommendations capture the full spectrum of management and environmental variability.

Equally important is the breadth of expertise within the committee. Soil scientists, agronomists, microbiologists, ecologists, modelers, and extension specialists bring complementary perspectives, enabling a systems-level approach to N management. The collaboration also provides unique opportunities to test emerging technologies, such as remote sensing and enhanced efficiency fertilizers, across diverse conditions. Extension and outreach specialists within the group ensure rapid dissemination of findings to producers, crop advisors, and policymakers. The strength of this multistate network is one of the project’s greatest assets, allowing it to deliver outcomes with both scientific rigor and practical relevance.

Potential impact

The renewal of NC1195 will deliver measurable advances in both agricultural productivity and environmental stewardship. By improving understanding of soil, manure, and fertilizer N dynamics, the project will help synchronize N supply with crop demand. This tighter alignment will lead directly to improvements in NUE, allowing producers to apply less fertilizer without sacrificing yield. More accurate recommendations will reduce the reliance on blanket application strategies, lowering input costs while improving profitability across the Corn Belt.

Environmental benefits will follow from these efficiency gains. With better accounting of soil and manure N contributions, fewer excess nutrients will escape into water bodies, reducing nitrate leaching and improving groundwater quality. At the same time, decreasing fertilizer over-application and adopting more targeted management practices will reduce atmospheric N emissions. Together, these outcomes represent a substantial step toward reconciling agricultural productivity with environmental sustainability.

Another key impact of the project will be the development of innovative decision-support tools. By integrating remote sensing, crop canopy sensors, UAV imagery, and predictive modeling, the committee will provide producers and advisors with in-season guidance to adjust N applications. These tools will give farmers confidence to reduce “insurance N” while maintaining yield stability, particularly under variable weather conditions. The incorporation of precision agriculture technologies into practical recommendations will help translate research advances into real-world improvements at the farm level. Finally, the renewal will strengthen the extension and outreach capacity of the committee. By developing educational materials, training programs, and regionally validated recommendations, NC1195 will ensure rapid dissemination of research outcomes to farmers, advisors, policymakers, and conservation professionals. This strong extension component will accelerate adoption of best practices and contribute to broader nutrient management initiatives across the region. Beyond the Corn Belt, the project’s integrated approach will serve as a model for sustainable N management in other intensive cropping systems worldwide.