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1. US Midwest Dairy Manure Nutrient Observations 2012-2022Dairy manure is a source of organic nutrients with variable manure characteristics. This analysis drew 2012-2022 data from ManureDB, the manure and organic amendment database developed by the University of Minnesota. Thousands of solid dairy and liquid dairy manure samples across 2012-2022 were evaluated for book value comparisons, temporal trends, and regional differences for total N, NH4-N, P2O5, and K2O analytes. The only significant trend detect... N. Bohl Bormann, M. Wilson, E.L. Cortus, K.A. Silverstein, K.A. Janni, L. Gunderson |
2. A Novel Use of Data Translation Allows 3D Prediction of Soil Fertility LandscapesSoil fertility managers need better estimates of the subsoil contribution to the nutrient pool. Thls need could be achieved through 3-D predictions of subsoil fertility using a novel method of soil- profile data translation in relation to a controlling genetic horizon. For this translation, the depth of a controlling pedogenic feature is used as the origin and the rest of the profile is linearly scaled to it. When applied to a group of soils, from across a local or regional landscape, with varyi... |
3. Aerial Photos Can Predict Corn Yield Loss Due to N DeficiencyFields that experience wet weather after N fertilizer is applied may lose N and consequently lose yield. Replacing N may be difficult or expensive after corn is too tall for tractor clearance. A tool to assess the degree of potential yield loss would help corn producers decide how much expense is justified in making late N applications. ... |
4. Arbuscular Mycorrhizal Dynamics Throughout Corn Growing SeasonPhosphorous is an essential plant nutrient and is the second most common fertilizer nutrient applied in crop production. The role of mycorrhizal fungi in phosphorous (P) nutrition of corn (Zea mays L.) in high fertility soils in unclear. A study was conducted to determine the effect of extractable P on myco~hizal biomass and to evaluate the temporal dynamics of mycorrhizal fungi during the growing season in two irrigated corn fields in Nebraska. The objectives were addressed by the installation ... |
5. Assessment of Nitrogen Supply From Poultry Manure Applied to CornThe production of poultry in the state of Iowa is one of the largest in the nation and growth has continued the past few years. Currently Iowa is the number one egg producing state in the USA (USDA, 2005). This increase in production also implies an increase in manure production from poultry sources. The common end use of manure is application for crop production. Concerns exist- regarding application at rates higher than needed for crop use, with potential for contamination of water bodies due... |
6. Balancing Agronomy and Environment: N Recommendations in Ontario for the 21st CenturyThe goal of a fertilizer program may be to maximize yields from each ficld, or to maximize profit, or to minimize environmental impact. Recent instances of groundwater contamination with nitrate have focused attention on the need for source water protection, and agriculture has been implicated as one of the sources of nitrate contamination. This has lead to concerns that environmental rules could reduce the profitability of crop production, by limiting fertilizer use and hence, crop yields. Addi... |
7. Beyond the Acre Furrow Slice: a New Era in Nutrient ManagementThe Midwest faces a pivotal shift in how we develop nutrient guidance for farmers. The long-running “build-up and maintenance” approach, built on decades-old soil-test methods, no longer aligns with today’s diverse and dynamic farming systems. Instead of anchoring decisions to soil depths tied to historical moldboard plow use, we should emphasize soil supply and plant uptake over time. Recommendations must be grounded in actual nutrient removal at harvest, on a site-by-... H.M. Brown |
8. Biological Nitrogen Suppliers for SoybeansSoybeans are known to require more N than most crops, largely due to the high N levels found in their seeds. The most important source of N for soybean plants is the biological N fixation process. However, high yields (above 70 bu acre-1) could limit the capability of this process to supply the plant's N demand. This study aims to investigate the use of non-rhizobial biological N suppliers, their ability to provide N to the soybean plants and potentially fill the N demand gap. The study w... V. Winnikes De Barros, S. Casteel |
9. Can Early Nitrogen and Sulfur Applications Sustain Soybean Yields After Cereal Rye?Cover crops such as cereal rye (Secale cereale L.) are widely promoted for their environmental benefits, including nutrient sequestration, reduced nitrate leaching, and soil conservation. However, their influence on subsequent soybean (Glycine max L.) yield and nutrient dynamics remains inconsistent, especially under varying nitrogen (N) and sulfur (S) fertilization regimes. Field trials were conducted during 2024 and 2025 across three sites in Central Illinois—Monmouth, Perry, and Urba... S. Canafoglia, G. Preza Fontes |
10. Closing the Yield Gap of Soybeans After Cereal Rye: How Limited S Application Can Affect Soybean PerformanceCereal rye is a common cover crop in the Midwest due to its overwintering biomass and soil fertility properties. Despite common adoption, research is still needed to improve soybean yield after cereal rye. Fertility management practices are needed to mitigate cereal rye immobilization of sulfur. These practices are integral for further cereal rye adoption at the farmgate. This study examines which combination of urea and/or gypsum is needed to enhance soybean yield in both cereal rye and no c... A. Antic, S. Casteel, S. Armstrong |
11. Critical Soil Test Phosphorus for Corn: Updates and Method Comparison in KansasPhosphorus (P) fertilizer recommendations in Kansas are currently based on legacy correlation–calibration studies and guidelines that do not account for crop-specific requirements. This lack of precision creates uncertainty in fertilizer management, raising the risk of both under-application, which limits yield, and over-application, which increases costs and environmental risk. The objective of this research was to update the critical soil test phosphorus value (CSTV) for corn (Zea... G. Roa , D. Ruiz Diaz |
12. Cropping System Diversification Has Strong Short-term but Limited Long-term Impacts on Soil Phosphorus DynamicsCrop diversification provides several agroecosystem benefits, yet the effects of extended crop rotations and livestock integration on soil phosphorus (P) dynamics are not well understood. We examined the effect of three cropping systems: a corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation with synthetic fertilizer (2 year), a corn-soybean-small grain rotation with red clover (Trifolium pratense L.) and composted cattle manure as a fertilizer source (3 yea... J. Kovar, C. Crespo, J. Berkey, P. O'brien, W. Huang, M. Liebman, M. Mcdaniel |
13. Determining Economic Optimum Nitrogen Rates with the Illinois Soil Nitrogen Test and Soil Organic Nitrogen FractionsDevelopment of a diagnostic test to estimate soil N supplying capability is a continuing research need. The Illinois soil nitrogen test (ISNT) has been proposed as a method for adjusting corn (Zea Mays L.) N recommendations for to account for soil organic N contributions. We evaluated the ISNT as a tool for predicting corn N response in Wisconsin by comparing ISNT values and corn N response data from-81 experiments conducted between 1984 and 2004 with a range of crop rotations, management histo... |
14. Determining the Economic Optimum Nitrogen Rate for Different Cover Crop Systems Using On-Farm Precision ExperimentationSuccessful integration of cover crops into corn-soybean production systems requires adjusting interconnected management factors. Nitrogen (N) is a critical input in corn production, and because cover crops influence nitrogen dynamics, it is essential to evaluate both as an integrated system. To address this, field trials were established in two locations near Moultrie County, Illinois, in the fall of 2023 and 2024 as part of a four-year project (2024–2027) aimed at improving the underst... M. Dalla Betta, J. Jones |
15. Does Inoculant or Sulfur Improve Nitrogen Fixation in Soybean After Long-term Corn?This study evaluated the effects on nutritional dynamics and productivity in soybean, focusing on nitrogen and sulfur management in fields with more than twelve years of continuous corn in the state of Indiana (USA). Continuous corn systems are known to alter soil microbial activity, leading to a reduction in the nitrogen-fixing bacteria population, which affects the biological nitrogen fixation process in legumes, such as soybeans, which rely on those bacteria to meet their nitrogen requirem... A. Brun, S. Casteel, D. Quinn, R. Wilhelm |
16. Effect of Barley and Winter Pea Cover Crops on Nutrient Availability in No-Till CornCover crops are reported to have long-term soil health improvements, the first of which is reducing erosion. However, popular cereal cover crops, such as rye (Secale cereale), have the potential to cause a yield penalty in the following corn (Zea mays) crop. Legumes, such as Austrian winter pea (Pisum sativum), are thought to reduce this yield penalty in no-till systems. Additionally, sulfur deficiencies have been observed in some studies following cover crops. The ... E. Marsh, C. Lee |
17. Effect of Cover Crop Diversity on Nitrous Oxide Emissions from Corn–Soybean Rotations in Central IllinoisNitrous oxide (N₂O) is a potent greenhouse gas primarily emitted from agricultural soils, where nitrogen (N) inputs and soil conditions interact to drive microbial processes. Cover crops are widely promoted as a climate-smart strategy to improve soil health and nutrient cycling, yet their effectiveness in mitigating N₂O emissions may vary depending on species composition and functional diversity. This study evaluated the influence of cover crop diversity on N₂O emissions in a corn&ndash... N. Guzman |
18. Effect of Manure Sources on Soil Phosphorus DynamicsPhosphorus (P) is essential for crop production, but it also causes water quality issues such as algal blooms. Crops typically utilize only 10-20% of applied P; the remainder accumulates in soil or is eroded/leached into water bodies, resulting in reduced fertilizer use efficiency and increased risk of eutrophication. This study evaluated the effects of different organic fertilization strategies on soil P pools across two sites in Ohio. Treatments included two manure-amended sites, one receiv... J. Singh, J. Ippolito, G. Labarge, M. Rakkar |
19. Effect of Timing of Broadcast Potassium (K) on Soybean Yield and Seed K ContentIn Indiana, the common practice is for K fertilizer to be applied in advance of the corn crop for both crops in the rotation, relegating soybean to feed on the application residual. Producers are concerned that current University guidelines and common practices for K management in corn- soybean rotations do not fully recognize the particular K needs of the soybean crop as differentiated from the corn crop. A four-location, six-year field study was conducted to investigate the effects of rate and... |
20. Effects of Anhydrous Ammonia Application Timing on Corn Yield and ProfitabilityNitrogen (N) application timing is a critical decision for Illinois corn (Zea mays L.) producers balancing operational efficiency, economic return, and environmental stewardship. This study compared agronomic and economic outcomes of fall versus spring anhydrous ammonia applications across 19 central Illinois sites from 2013 to 2020, using a randomized complete block design with N rates from 0–361 kg N ha-1. Yield response to N was analyzed to determine agronomic optimum N ra... J. Jones, B. Link, E. Nafziger |
21. Effects of Nitrogen and Irrigation Management on Sugar Beet Yield and Nitrous Oxide EmissionsSugar beet (Beta vulgaris L.) is an important sugar-producing crop, accounting for about 55% of total sugar production in the United States. Optimizing nitrogen (N) and irrigation management is essential for achieving profitable and sustainable beet production. Excessive N application can lower sugar quality and increase nitrous oxide (N₂O) emissions, a potent greenhouse gas and ozone-depleting compound. This study evaluated the effects of irrigation and N fertilizer (urea) rates on su... S. De Silva, B. Maharjan |
22. Efficient Nitrogen Strategies for Hybrid Winter RyeEfficient nitrogen (N) management is essential to maximize hybrid winter rye (Secale cereale L.) yield. Given limited information on how N rates, application timing, and fertilizer sources affect production in the U.S. Midwest, yield responses were evaluated under various N management strategies. This experiment included a pre-plant application of 30 lb N ac⁻¹ in the fall, followed by spring applications to evaluate eight N rates (0–210 lb N ac⁻¹) and investigate the effec... M.L. Costa, J. Clark, V. Nunes, P. Sexton |
23. Emerging Trends from Wisconsin’s Nitrogen Optimization Pilot ProgramAccurately determining nitrogen (N) fertilizer requirements for crops is challenging due to the wide variability in landscapes and field management across the state. Adjusting nitrogen rates comes with a high level of risk considering over-application can reduce profits and negatively affect water quality, while under-application can prevent yield targets from being reached. Conducting field-scale, on-farm research is a practical approach to better estimating optimum N rates on a fi... M. Schauer, M. Ruark |
24. Evaluating Classification Methods for Phosphorus Responsiveness for Fertilizer RecommendationsField crop yield responses to fertilizer applications are often uncertain, and the likelihood of a response at a given site is typically determined using correlation-based soil test methods whose accuracy is not well established. The objective of this study was to evaluate three alternative approaches to classify field sites as responsive or non-responsive to phosphorus (P) fertilization in wheat. The methods tested were: (i) a linear-plateau correlation model, (ii) a linear-plateau correlati... D. Ruiz Diaz, S. Cominelli, J. Lacasa |
25. Evaluating Commercial Nitrification Inhibitors Under Variable Soil ConditionsNitrification inhibitors (NIs) are commonly used agrochemicals designed to slow the conversion ammonium to nitrate, which has the potential to reduce environmental losses of nitrogen and improve nitrogen fertilizer recovery efficiency. However, their efficacy can be highly variable and is dependent upon soil and environmental characteristics which can vary by geographic location and agricultural production system. This experiment involved a laboratory incubation designed to evaluate the perfo... R. Roth, A. Ludolph |
26. Evaluating Near-infrared Spectroscopy for Predicting Soil Chemical Properties in KansasSoil testing is fundamental for accurate fertilizer recommendations and effective nutrient management. However, traditional wet chemistry methods are time-consuming, labor-intensive, and costly. Near-infrared spectroscopy (NIRS) offers a faster and more sustainable alternative by estimating soil chemical properties from light absorption and reflection between 350 and 2500 nm. This study aimed to develop Kansas-specific NIR calibration models to evaluate the applicability of this technique for... S. Cominelli, D. Ruiz Diaz |
27. Evaluating Soil Health Indicators in Response to Tillage, Crop Rotation, and Cover CroppingSoil health is shaped by management practices that influence soil physical, chemical, and biological properties. Conservation practices such as reduced-disturbance tillage, cover cropping, and diverse crop rotations are increasingly promoted for improving soil structure, nutrient cycling, and microbial activity. However, the extent to which these practices interact and whether newly adopted no-till systems show similar benefits to long-term reduced tillage remains unclear. This study evaluate... S. Mesman, J. Clark, V. Nunes, P. Sexton |
28. Evaluating Soybean Yield and Soil Fertility Response to POLY-4 As a Sulfur and Potassium SourceBoth sulfur (S) and potassium (K) play an essential role in soybean growth and metabolism, immunity against insect-pest and improving yield quality and quantity. Reduction in atmospheric deposition of S in soil in recent years has increased the risk of S deficiency in crops. POLY-4 is a novel S and K source containing 19% S, 14% K2O, 17% CaO, and 6% MgO with properties like slow nutrient release and high nutrient use efficiency. It can be used to address the issue of S deficiency in plants. A... R. Kaur, K. Nelson, G. Singh , G. Kaur |
29. Evaluating Spatial Attribution for Continuous Improvement of Fertilizer RecommendationsThe theory behind precision agriculture is driven on the improvement of every acre. While spatially driven recommendations have been practiced for greater than 30 years, the benefits of precision agriculture have largely not been realized. Today’s precision fertilizer recommendations have generally utilized traditional attributes (for instance: soil test phosphorus, soil test potassium, and in some application recommendations, other analyzed attributes from soil test evaluat... W. Berg |
30. Evaluation of Slow Release Nitrogen Materials in Corn ProductionStudies were conducted over a two year period to evaluate two slow release urea nitrogen carriers with regular urea for the production of corn on iirigated Spinks loamy sand. Because nitrogen availability in the soil is quite transient fiom one season to the next, annual addition of nitrogen is important for maximu~n corn yields. Many corn producers prefer to apply most of the nitrogen prior to planting corn. Once incorporated into the soil, nitrogen containing materials, such as urea, are conve... |
31. Fate of 15N-Labeled Urea Applied In-season for Corn in Eastern North DakotaNitrogen (N) fertilizers represent a major investment for North Dakota cropping systems as evidenced by the 890,000 tons of N used by producers in 2024 alone. If these inputs are to be beneficial to the producer and not harmful to the environment, they must be managed efficiently. To evaluate the efficacy of split-N applications, 15N-labeled fertilizer was applied to three different soil types in eastern North Dakota, including an irrigated sand, a smectite rich clay, and clay loam... M. Culpitt, K. Griesheim |
32. Fertilizer Derived Nitrogen Dispersion in Minnesota Corn with Rye and Kura Clover Cover CropsWhile ideally all fertilizer nitrogen (N) is utilized by crops, much can be lost to the environment as nitrate (NO3), nitrous oxide (N2O), or ammonia (NH3). To enhance agronomic systems and mitigate environmental N dispersion, best management practices can be utilized. Here, urea was applied to continuous corn at 250 kg N/ha or a 0 kg N/ha control, and with select cover crops (no cover, winter rye, kura clover) to assess practices that may result in optimal fe... J. Kastenbauer, F. Fernández, V. Sharma, R. Venterea, J. Spackman |
33. Fertilizer Nitrogen Source and Management Impacts on Greenhouse Gas EmissionsAgricultural soil management accounts for nearly 6.3% of all greenhouse gas emission in the U.S. Although fertilizer nitrogen is an essential coinponent of nearly all agricultural systems, the addition of reactive N to soils and the emission of nitrous oxide (N20) via soil microbiological processes (nitrification and denitrification) makes U.S. agriculture the largest source (62%) of total U.S. N20 emissions. Because N20 is a potent greenhouse gas with a forcing potential more than 300 times gre... |
34. Field Correlation and Calibration of Soil-Test Phosphorus and Potassium for Corn and Soybean in IllinoisEffective phosphorus (P) and potassium (K) soil-test interpretation and fertilizer guidelines require each soil test to be field correlated with crop yield response to fertilization and calibrated to provide expected response probabilities. University of Illinois P and K guidelines require updates to reflect routinely used soil-test methods and current cropping systems. Field studies were established at seventeen sites across Illinois to correlate soil-test P and K with corn and soybean respo... F. Bardeggia, J. Jones |
35. From the Ground Up: a Farmer-Led On-Farm Research Evaluating the Potential of a New Fertilizer Source for Nitrogen in Pastures for MissouriThis research is a part of a transdisciplinary network of farmers leading on-farm research and innovation groups across Missouri, where farmers are leading the design and implementation of nitrogen (N) fertilizer treatments. The Objective of this on-farm research trial in southwest Missouri is to determine whether green lightning fertilizer technology can fulfill the N requirement of pasture in a more economical and sustainable way than the conventional sources of N. The cost of N f... K. Deep, R. Carson, G. Singh, J. Vredenburgh |
36. FRST Lime Project: Results of Pilot Study of Lime Source, Lime Rate and Incubation Time on Neutralization of Soil AcidityManagement of soil acidity plays a critical role in the agriculture across North Central Region. The Fertilizer Recommendation Support Tool (FRST) group has launched a national project to develop new lime recommendations and has collected 144 soils of which 38 soils from the North Central Region. A pilot lime study was initiated to assess the effect of lime source, lime rate and incubation time on neutralization of soil acidity. Three acid soils were selected from the Agricultural Proficiency... B. Miller |
37. How Do Cover Crops, Nitrogen Rate and Cropping System Affect Nitrate Loss in Tile Drainage Water?A field research study was conducted on clay loam soil in Waseca Minnesota. The objectives were to quantify the effects and interactions of cover crops, nitrogen (N) fertilizer rates and cropping system on corn production and nitrate-N concentration and loss in tile drainage water. Cover crop treatments [cereal rye and a blend of annuals (oat, forage pea and radish)] were drilled soon after corn silage harvest each fall. Nitrogen treatments were split-applied at planting and V3 growth stage. ... J. Vetsch, A. Cates |
38. Hybrid Maize A Simulation Model for Improving Corn ManagementHybrid-Maize (www.hybridmaize.unl.edu) is a computer program that simulates the growth and yield of a corn crop under non-limiting or water-limited (rainfed or irrigated) conditions. The model can be used to (1) assess the overall site yield potential and its variability based on historical weather data, (2) evaluate changes in attainable yield using different combinations of planting date, hybrid maturity and plant density, (3) analyze yield in relation to silking and maturity in a specific yea... |
39. Impact of Ammonia Reduction Management Practices in Land Applied Manure on Nitrogen Losses and Nitrogen Use EfficiencyDairy manure is a valuable nitrogen (N) source in crop production, but N losses through volatilization and leaching diminish its nutrient value and pose environmental risks. Proper manure management practices can enhance nitrogen use efficiency (NUE) and mitigate these environmental concerns. This ongoing two-year field study evaluates different manure application methods and assesses their tradeoffs regarding N leaching and NUE. The study involves six experimental treatments, each applying 9... J. Bukomba, R.A. Larson, M. Ruark, X. Zhu-barker, N. Rayne |
40. Impact of Nitrogen and Sulfur Fertilization on Wheat Yield and QualitySulfur (S) contributed by rainfall has decreased by 50% over the last twenty-seven years and may increase the need for S supplementation by fertilization. Nitrogen (N) application is typically split applied in Ohio with some applied in the fall and remainder applied in the spring near first green-up. The objective of this study was to compare N application source and timing with and without S fertilization. Two experimental locations were established in the fall of 2004. Urea and urea-ammonium n... |
41. Impact of Phosphorus Source and Timing on Corn Yield and Root GrowthPhosphorus (P) management is critical in maize production due to limited mobility, solubility, and stratification in soils. This study evaluates P application techniques with regard to maize grain yield, total P uptake, and root distribution. Our hypothesis was that applying P as a side dress in a low P soil at a low dose equal to plant uptake can compensate for not maintaining soil test P at the critical level, providing sufficient P during peak demand and sustaining high yields. A gre... A. Beltrame, C. Penn, D. Quinn, M. Williams, C. Zhang |
42. Impact of Stratified Potassium and Water Content of No-Till Soils on Soybean Growth and YieldLow potassium (K) concentrations in subsurface soil and reduced water content in the K- enriched surface soil are thought to cause K-related yield reductions in rain-fed soybean (Glycine max L. Merr.). Our objectives were to examine root-to-shoot ratios through ontogeny and yield components in relation to stratified soil water and K. Soil and plant samples were collected at V6, R2, R4, and R6 from a 2-year field study. Additionally, a greenhouse split-root ot study in P a complete factorial des... |
43. Impacts of Management Practices and Soil Properties on Free-Living Nitrogen Fixation in Southeastern South DakotaModern agriculture relies heavily on synthetic nitrogen fertilizer, raising environmental concerns due to overuse. Biological dinitrogen (N2) fixation offers a sustainable alternative, with free-living diazotrophs playing a crucial role alongside well-known symbiotic nitrogen-fixing bacteria. Recently, interest in free-living nitrogen fixation (FLNF) has grown due to its potential contribution to sustainable agricultural practices. However, there is limited scientific data on FLNF ... L. Galvan Nuevo, A. Blume, V. Nunes |
44. Improving Corn Grain Yield and Reducing Nitrate-N Leaching with Urease and Nitrification InhibitorsSustainable corn (Zea mays L.) production requires proper nitrogen (N) management to optimize yield and minimize negative impacts of N losses on water quality. Nitrification inhibitors could be a viable strategy to synchronize N availability and corn N demand and decrease N loss through nitrate-N leaching. A field study was laid out in a randomized complete block design with five replicates at the Belleville Research Center (2023-24) and the Agronomy Research Center (2024-25), IL, wi... S. Koduru, O. Guzel, J. Mcgrath, M. Javid, O. Ola, E. Brevik, A. Sadeghpour |
45. Improving the Fermentation Characteristics of Corn Through Optimum Fertilization and Hybrid SelectionEthanol processors could increase production efficiency if they had access to corn grain better- suited for fermentation. The objective of this study was to determine the influence of hybrids and N fertility rates on fermentable starch content that will be used for dry-mill ethanol production. Six hybrids were grown under four N fertility levels at two locations in eastern SD. Ethanol yields increased as N fertility levels increased. Higher ethanol yields were achieved by hybrids that produced b... |
46. In Season RecommendationsWe are testing a prototype high-clearance tractor configured with active crop canopy sensors, drop nozzles with electronic valves, and a variable rate controller as means to deliver in-season variable rates of liquid N fertilizer based on crop needs as an alterative to preplant uniform applications of N. The active sensor we're evaluating is the model ACS-210 Crop Circle made by Holland Scientific. It generates it's own source of modulated light in the amber and near infrared (NIR) bands and the... |
47. Industrial Hemp Response to Nitrogen Applications in MissouriIndustrial hemp (Cannabis sativa L.) is gaining attention as a multipurpose crop for fiber, grain, and biomass, but research-based region-specific guidelines on nitrogen (N) management are limited. To address this gap, field experiments were conducted at two locations (Albany, Novelty) in northern Missouri in 2024 & 2025 to evaluate the effects of N applications on industrial hemp growth, biomass, and grain yield. The experiments were laid out as a randomized complete block ... A. Nain, G. Kaur , K. Nelson, G. Singh, M. Davis |
48. Influence of Nitrogen Fertilization Frequency and Rate on Nitrous Oxide Emissions in Winter WheatManaging nitrogen (N) fertilizer effectively is important for reducing nitrous oxide (N2O) emissions in farming systems. This study examined the effect of N application frequency and rate on winter wheat (Triticum aestivum L.) grain yield, total N₂O emissions, and yield-scaled N₂O emissions. The experiment was conducted at the Agronomy Research Center (ARC), Southern Illinois University, Carbondale. A randomized complete block design (RCBD) was used ... O. Ola, O. Guzel, K. Gage, K. Williard, J. Schoonover, S. Mueller, E. Brevik, A. Sadeghpour |
49. Influence of Nitrogen Management and Precipitation on Sorghum Nitrogen Use Efficiency in KansasGrain sorghum (Sorghum bicolor L. Moench) is a key crop in Kansas which can benefit from optimized nitrogen (N) management that enhances yield while minimizing N losses. Understanding the relationships among physiological efficiency (PE), recovery efficiency (RE), and agronomic efficiency (AE), as well as their interactions with climatic factors such as precipitation, is essential for improving nitrogen use efficiency (NUE). Experiments were conducted across five r... M. Platero, D. Ruiz Diaz |
50. Influence of Soil Amendments and Topographic Position on Winter Wheat Heavy Metal UptakeField crop heavy metal accumulation poses a major challenge for reducing food contamination and is governed by complex interactions between soil physical and chemical properties, climatic conditions, and intrinsic plant traits. Addressing these challenges requires an understanding of heavy metal accumulation during crop development and effective pre-harvest field mitigation strategies. Two winter wheat (Triticum aestivum L.) field studies were conducted in Michigan focusing on 1) fer... K. Steinke, M. Suplito, Z. Hayden |
51. Integrating NDVI and Plant Tissue Analysis As Decision Support Tools for Nutrient Management in Winter WheatEfficient nitrogen (N) management is critical for improving winter wheat grain yield and protein content while minimizing costs and environmental risks. Remote sensing indices, such as the Normalized Difference Vegetation Index (NDVI) and physiological indicators, like flag leaf N content, have been proposed as predictors of crop performance that could support in-season N management decisions. This study evaluated the relationships between NDVI measured at multiple growth stages, flag leaf N ... J. Leiva, D. Ruiz Diaz |
52. Interpreting Soil Health Test Results to Guide Management for Missouri Row CropsSoil health determines long‑term productivity, nutrient cycling, water retention, and resilience in row‑crop systems. Missouri-specific, data-driven framework for interpreting six complementary soil health indicators—total organic carbon (TOC), permanganate-oxidizable carbon (POXC), 3-day soil respiration, wet aggregate stability (WAS), autoclaved citrate-extractable (ACE) protein, and potentially mineralizable nitrogen (PMN)—was developed by the University of Missouri Soil He... G. Singh , K. Nelson, M. Parvej, D. Brandt, R. Myers |
53. Introgressing Unique Sources of Germplasm to Improve N Use in Temperate MaizeThe vast majority of maize breeding efforts have been conducted under high N environments that primarily select for only one component of NUE, N uptake. Furthermore, these studies have employed US. and European genotypes, which have been selected for performance at high N. Historically, maize was grown in numerous low N tropical environments, suggesting that evaluation of adapted maize lines containing tropical germplasm may harbor useful genetic variation and novel alleles for improving NUE. Th... |
54. Investigating Potassium Fertility in Indiana: K Rates and Nutrient InteractionsAdequate potassium (K) nutrition is critical for optimal plant growth and yield production in both corn and soybeans. Ongoing trials across the state of Indiana have been investigating K rate response in corn and soybeans in different environments. Treatments range from 0-180 lbs K2O/ac as potash. Results from these studies will be discussed. Additionally, new in 2025, NxS and NxK trials were conducted to investigate the effect of K nutrient interactions on corn yield. Treatments i... D. Quinn, A. Helms, M. Bourns |
55. Investigating the Need for Sulfur for Kentucky Wheat ProductionSulfur (S) deficiencies in Kentucky wheat production are increasing due to a reduction in atmospheric S deposition, greater removal in grain and forage, and less S contamination in phosphorus fertilizers. The University of Kentucky currently does not provide S recommendations based on S soil test results. This is largely due to the Mehlich 3 soil test extractant not being correlated or calibrated for S response in Kentucky crops and the lack of S responsive fields. Surveys and studies were co... E. Ritchey, J. Grove |
56. Linking Soil Properties and Weather Variability to Nitrogen Fertilizer NeedsSoil Nitrogen (N) availability is known to be affected by weather and soil characteristics. Current fertilizer recommendations are generally based on yield goals, soil type, and past productivity; however, these methods frequently fail to account for the constantly changing interactions between soil biological, chemical, physical and weather variables that influence N availability. This limitation increases uncertainty in estimating the economic optimum nitrogen rate (EONR), potentially reduc... S. Dangal, J. Clark, P. Kovacs, V. Nunes, C. Graham |
57. Long Term Outlook On Nitrogen and Potassium SupplyThe North American fertilizer industry is operating in world market today. Worldwide fertilizer demand, competition for transportation, and natural gas prices are all putting pressure on North American fertilizer prices. The themc of this mornings' session is on strategies the supply industry and fanners may adopt to manage these pressures. This talk is about the near future outlook nitrogen and potassium fertilizer. Fertilizer sales figures indicate that nitrogen, phosphorus. and potassium fer... |
58. Making Urea Work in No TillNo-till and reduced tillage production systen~s are widely used today in the United States as well as around the world due to their capacity for reducing soil erosion and topsoil loss, reducing phosphorus movement to surface water, and reducing labor, fuel, and equipment requirements. In no-till systems, an average of 25% of the N applied as broadcast urea can be lost via ammonia volatilization. Therefore, N losses due to ammonia volatilization will decrease corn and wheat yields. independently ... |
59. Managing Continuous Corn for High YieldsMany "contest-winning" corn yields have historically been produced in fields where corn is grown continuously, often with extensive tillage, hgh soil test values of P and K, high N rates, and high plant populations. We are conducting a series of research trials at four sites in Illinois, in whlch we are varying tillage, fertilizer rates, and plant population in a factorial experiment at several Illinois locations. Over ten site-years to date, tillage deeper than normal increased yield at two sit... |
60. Near Seed Application of Fluid Fertilizer for Corn Soybean and Sugarbeet ProductionIn recent years, crop producers in Minnesota have shown increased interest in placing fertilizer near the seed at planting. The more traditional 2x2 "starter" band was not an option. Guidelines were needed for banded placement of fertilizer near the seed at the time of planting. This study was conducted in 2004 and 2005 in fields of cooperating crop producers. Three fluid . materials (10-34-0, 4-10-10, 3-18-18) were applied at two rates for corn, soybeans and sugarbeets. In 2004, the materials w... |
61. Nitrogen Effects on Forage Utilization and Economic Returns in Grazing and Haying SystemsForage productivity and profitability are essential in both grazing and haying systems. This study evaluated haying and rotational grazing systems and nitrogen rates compared to overseeding birdsfoot trefoil (Lotus corniculaatus; BFT) on an Armstrong Loam (Aquertic Hapludalfs). Forage biomass was consistently higher under grazing, with its advantage widening as N increased. Both systems displayed diminishing marginal returns, but grazing achieved greater fertilizer efficiency, produc... E. Oppong Adjei, R. Carson, J. Lory, K. Nelson |
62. Nitrogen Fertilizer Application Consultation Tool (N-FACT)The N-FACT is a decision support web tool that leverages data from the Iowa Nitrogen Initiative on-farm nitrogen rate trials with cropping systems modeling. The web tool was released in February 2025 (https://n-fact.ag/start). The web tool summarizes results on optimum nitrogen fertilizer rate for corn from hundreds of on-farm trials across Iowa. Additionally, the web tool allows users to select a county, crop rotation, planting date, fall... S. Archontoulis |
63. Opportunities and Limitations of Automatic Steering TechnologiesIn the short span of 10 years we have gone from using the Global Positioning System (GPS) to locate ourselves in a farm field, to automatically steering a machine working in the field. This application requires about 15 conlponents with each component evolving at a rapid pace. A number of conlpanies have formed to provide automatic steering packages as aftermarket retrofits. At a slightly slower pace, the main equipment manufactures are engineering machines that will be factor ready or factory e... |
64. Optimizing Nitrogen Application in Corn with and Without a Nitrification InhibitorDetermining an accurate nitrogen (N) recommendation for corn production presents significant challenges due to its complexity with N transformation and losses. A careful diagnosis and decision making is required for optimizing the N management in corn. Therefore, a three-year (2023-2025) field study was conducted to evaluate the effects of varying nitrogen (N) application rates and timings with the use of a nitrification inhibitor (NI) on corn grain yield and productivity. The study was arran... R. Paul, G. Singh , K. Nelson, G. Kaur , M. Parvej |
65. Optimizing Nitrogen Inputs in Malting Barley ProductionIn 2024, North Dakota produced 14.6% of the United States 144 million bushels of barley. Nitrogen (N) availability is a key factor influencing production and as sustainability becomes a priority, reducing greenhouse gas (GHG) emissions through enhanced efficiency fertilizer is essential. This study evaluated the effect of N application source on spring barley (Hordeum vulgare L.) grain yield and quality, as well as estimating N use efficiency (NUE). Field trials took place in 2025 at... B. Goettl, M. Martinez De Souza |
66. Phosphorus and Potassium Place in Corn-Soybean Systems in the Midwest: Possibilities with Automatic Guidance TechnologyGlobal positioning system teclmology available to the public has become more accurate in recent years. Current Real Time Kinematic (RTK) techniques allow relative positions of equipment to be recorded with 3/8 - 2 in. precision (Dana, 1991). Being able to return to the same location in the field year after year with high precision may have implications for corn-soybean systems where banded applications of phosphorus (P) and/or potassium (K) are made at a time other than at planting. The importan... |
67. Phosphorus Fertilizer Management: Implications on Crop Yields and Soil P BudgetsRecent volatility in fertilizer prices, declining commodity values, and increasing water quality concerns have intensified scrutiny around phosphorus (P) management decisions in Ohio. In response, we initiated a field trial to evaluate crop yield response and soil phosphorus budgets under various P application strategies within a corn–soybean rotation during the 2024 and 2025 growing seasons. The study investigated two P application timings (fall and spring), two fertilizer sources (tri... M. Rakkar, B. Robinson |
68. Picking the Right Nitrogen Recommendation Tool to Improve NUE and Water Quality in NebraskaThe comparison of static versus dynamic nitrogen (N) recommendation tools has gained significant attention for enhancing N management in the U.S. Midwest maize production. However, both approaches have limitations in performance under variable field conditions. This two-year study (2021–2022) evaluated the agronomic, environmental, and economic outcomes of a static Nebraska Yield Goal (NE YG) tool against four dynamic N tools: Maize-N, canopy reflectance sensing, Granular, and Adapt-N. ... J. Iqbal, A. Singh |
69. Predicting Nitrogen Response by Winter Wheat Using Soil Health and Soil Microbiome IndicatorsEfficient nitrogen (N) management is critical for improving profitability and sustainability in winter wheat production systems of western South Dakota, where soils and growing conditions vary widely. Current fertilizer recommendations rely heavily on soil nitrate-N, often overlooking contributions from organic N sources and soil biological activity. This project aims to refine N fertilizer recommendations by integrating soil health indices (SHIs) and soil microbiome analysis as predictors of... C. Graham, R. Jain |
70. Regional Approach to Making Nitrogen Fertilizer Rate Decisions for CornNitrogen fertilizer is one of the largest input costs for growing corn. Across the Corn Belt, N is typically the most yield-limiting nutrient. Facing record high N fertilizer prices and potential supply problems, producers are concellled about N fertilization rates. Soil fertility researchers and extension specialists froin seven states across the Corn Belt (see list in acknowledgements section) have been discussing corn N fertilization needs and evaluating N rate recommendation systems for appr... |
71. Role of Winter Rye Cultivar and Seeding Rate in Managing Residue and Nitrogen Availability in Corn Cropping SystemsWinter cereal rye (Secale cereale L.) (WCR) is the most widely used cover crop in Illinois and is recognized as one of the most effective in-field practices to reduce nitrate-N and phosphorus (P) losses to the Mississippi River Basin (MRB). However, adoption of WCR prior to corn (Zea mays L.) remains limited due to challenges such as stand establishment and nitrogen immobilization. Management strategies, such as selecting appropriate cultivars and optimizing seeding rates, m... S. Babaei, C. Kula, Y. Samadi, E. Brevik, A. Sadeghpour |
72. Scale of Measurement Effects on Phosphorus Runoff Losses from CroplandAs phosphorus (P)-based nutrient management planning becomes necessary for some farms in Wisconsin, it will be critical to have reliable, research-based planning tools. The Wisconsin P- hdex provides one method for preparing P-based nutrient management plans. The P-Index was developed largely from small plot-scale data showing the relationships between various site and management variables and runoff P losses. Thls study was conducted to compare runoff composition measurements at the subwatershe... |
73. Sensor-based Nitrogen Management Affects Corn Production and Environmental N FootprintsTo improve air and water quality, nitrogen (N) management in corn production systems should shift from the current N decision support system [maximum return to N (MRTN)], which suggests a single rate N addition, to sensor-based (GreenSeeker) active N management (variable N rate approach). Single rate N recommendations often result in under- and over-N addition and either increase environmental N losses or cause corn yield penalty. Our objectives were to evaluate corn optimum nitrogen N requir... A. Sadeghpour, O. Guzel, M. Guzel, J. Mcgrath, O. Adeyemi, E. Brevik, S. Koduru |
74. Slow Release Nitrogen Fertilizer and Dynamics in Soil Systems Part I Incubation StudyA lab study was conducted at Southern Illinois University soil fertility research facility to investigate the effects of soil type on the nitrogen (N) release dynamics. The objective of this study was to identify the effect of soil type on the release rate of N from slow release nitrogen (SRN) fertilizers under controlled conditions (moisture and temperature). Two contrasting soils from Iowa and Georgia (pH and mineralogy) were combined with 500 mg kg-, of SRN or urea and kept for 90 days under ... |
75. Soil Health Responses to Interseeded Cover Crops and Nitrogen Strategies in the Northern Corn BeltCover cropping and nitrogen (N) management are often promoted for improving soil health, yet their combined influence under interseeded systems in temperate regions remains less understood. To address this gap, a field study was conducted in South Dakota at two no-till corn–soybean rotation sites (Brookings and Beresford) established on clay loam soils. Cover crop treatments included a no cover, a single grass species, and a multi-species mixture of grass and broadleaf species interseed... J. Clark, S. Kodali |
76. Soybean Response to Tillage, Row Spacing and Nutrient Management Practices in Southern IllinoisConservation tillage improves long-term soil health and water quality but may reduce early soybean (Glycine max L.) growth due to cooler, wetter soils and limited nutrient availability. This study evaluated integrated management strategies, including tillage, row spacing, and starter nitrogen (N) and sulfur (S) fertilization, to optimize soybean performance under Illinois conditions. Field trials were established in 2024 in southern Illinois. Two split-plot experiments were conducted... E. Brevik, A. Sadeghpour, F. Rolle, D. Schaefer, G. Preza Fontes, M. Javid |
77. Soybean Yield Response to Nitrogen and Sulfur Starter Fertilizers Under Conservation TillageContext: No-tillage and cover crops adoption remain limited across the U.S. North Central region due to concerns about potential yield penalties in cash crops. High residue levels can slow soil warming and mineralization and promote nutrient immobilization, often leading to limited early-season nitrogen (N) and sulfur (S) availability for soybean. Objective: Evaluate soybean grain yield response under different tillage systems and assess the potential of N and S starter fe... F. Rolle, G. Preza Fontes, D. Schaefer, J. Vossenkemper |
78. Strip Tillage and No Tillage Fertilization Systems Evaluated for Eastern Kansas Rain Fed CornRow-crop agriculture in East-Central and Southeast Kansas is facing increasing pressure to reduce sediment and nutrient losses via runoff. Edge-of-field measurements show that no-tillage with fertilizers placed below the surface of the soil has significantly less sediment and total P losses in runoff compared to conventional tillage (Janssen et al., 2000). However, for rain-fed corn, no-tillage in these regions can provide serious challenges some years because of frequent spring rains and an abu... |
79. Study on Phosphorus and Nitrogen Concentration of Corn Adapted in South DakotaThough nitrogen (N) and phosphorus (P) are vital in several physiological and developmental processes in plants and animals, they pose several environmental, nutritional and health problems, if present in excess amounts. Reduction in the excess input of these nutrients into the soil, thereby reducing environmental problem and consequently nutritional and health problem, can be achieved by balancing their concentration in animal feed. Therefore, this research aims to quantify the nitrogen and pho... |
80. Swine Manure Phosphorus Use for Crop Production in IowaImproving manure phosphorus (P) management guidelines should result in a more efficient use of thls resource for crop production and in lower risk of P loss to surface water resources. Phosphorus fertilizers are widely used in crop production, there is a great deal of information about their use, and farmers have little doubt about their value to improve crop yield in low- testing soils. However, there is a great deal of uncertainty concerning the value of manure nutrients for crops and about co... |
81. Technology, Innovation, and the Future of Soil FertilityThis panel will focused on how technology is being used in the practice of soil fertility and nutrient management. Panelists will also discuss how they’ve incorporated new and old soil fertility concepts into their approach to guiding fertilizer use. Lastly, we will discuss where soil fertility is going as a scientific discipline. ... H.M. Brown, W. Berg, R. Mullen |
82. Terrace Construction Effects on Soil Fertility, Texture and Apparent Electrical ConductivityThe Midwestern United States is extensively dominated by sloping terrains, where terraces are recognized as a tool to minimize soil erosion. The process of terrace construction involves heavy machinery and extensive soil profile manipulation, which may alter soil fertility and texture. This study evaluated the changes in soil fertility, texture, and apparent electrical conductivity (ECa) following the construction of eight broad-based terraces in northern Missouri. Geo-referenced soil samples... C. Bansal, G. Singh , G. Kaur , K. Nelson |
83. The Effects of Phosphorus and Potassium Application on a 14-year-old Miscanthus × giganteus StandMiscanthus × giganteus (miscanthus) is a perennial C4 grass grown for renewable bioenergy and bioproducts. While miscanthus is often considered to have low nutrient requirements, the need for fertilization remains poorly understood, particularly in mature stands. This study aims to provide insight by evaluating for potential phosphorus (P) and potassium (K) limitations in a 14-year-old miscanthus stand in central Iowa that had received no prior fertilization. The experiment fol... J. Studt, A. Larson, A. Vanloocke, M. Mcdaniel, E. Heaton, N. Boersma |
84. The Future of Soil Fertility - My Two CentsThis presentation will provide information of what a large cooperative is currently providing customers in the realm of nutrient management. Additionally, some insight will be provided on how other aspects of nutrient management (global markets, production technologies, etc) are being evaluated. Finally, some general ideas will be shared regarding the future needs of the retail sector along with some research ideas. ... R. Mullen |
85. The Impact of Shifting from N-based to P-based Manure Management on Corn Silage Yield, Quality, P Balance, and Soil Test PDairy farmers often apply liquid manure to corn (Zea mays L.) for silage to meet N needs (N-based) which results in over-application of P and increased soil test P (STP) levels. A solution to this manure management is switching from N-based to phosphorus (P)-based (P removal based) manure management and supplementing N need with inorganic fertilizer. Intensifying corn for silage rotation with cereal rye (CR; Secale cereale L.) as a forage source could further decrease STP, e... G. Burkett, E. Brevik, S. Babaei, O. Adeyemi, A. Sadeghpour |
86. The Influence of Nitrogen Rate and Foliar Fetilization on Yield and Nitrosamine Levels in Burley TobaccoMany burley tobacco (Nicotiana tabactm~ L.) producers believe that additions of nitrogen (N) rates greater than those recommended by university extension senices will result in increased yield and income. In addition to high rates of N, many producers feel that additional foliar fertilizer will further increase yield and quality of burley tobacco and result in greater revenue. Concerns with excessive N additions include improper curing, elevated levels of tobacco specific nitrosamines (TSNA's), ... |
87. The Manitoba Greenhouse Gas Assessment ToolMethane (CH4) and nitrous oxide (N2O) are potent greenhouse gases (GHGs) emitted by agriculture. Manitoba Agriculture has developed an educational GHG assessment tool that allows farmers to evaluate annual emissions of these GHGs from their practices and explore the impact of changing practices. The first phase of the GHG assessment tool consists of annual estimates of N2O and CH4 emissions from soil and crop management practices, livest... P. Loro, M. Riekman, C. Sawka |
88. Two-sided Banding of Nitrogen and Sulfur Fertilizers Improves Maize Yield and Nutrient Use Efficiency in Midwestern Cropping SystemsEfficient fertilizer management is essential for maximizing crop yield while minimizing environmental impacts. Optimizing fertilizer placement is a key strategy for improving nutrient recovery and synchronizing nutrient availability with crop demand. Traditionally, fertilizer banding in Midwestern maize (Zea mays L.) systems is done on one side of the plant. This study evaluates the impact of two-sided banding of nitrogen (N) and sulfur (S) fertilizers on maize yield and nutrient use... A. Yakubu, A. Ludolph, A. Diop, A. Yakubu, R. Roth |
89. Understanding Wheat Head Counts Effect on YieldWheat (Triticum aestivum) is grown in many parts of the world, with soft red winter wheat (SRWW) being the most popular type grown in Kentucky. Wheat is the fourth most economically important crop in Kentucky and is used in a variety of food products as well as in feed for livestock. Crop scouts reported wheat head counts above the current University of Kentucky threshold for head counts needed to maximize yield. Wheat in other states north reported higher head counts than those obse... A. Mutter, C. Lee |
90. Updating Oat Nitrogen Fertilizer Rate GuidelinesThe current yield-goal based system for calculating oat N rate recommendations in SD has not been evaluated for accuracy recently. There are two main N rate recommendation systems used in the U.S.–Yield goal and maximum return to N (MRTN). Therefore, the objective of this project was to 1) evaluate the accuracy of the current yield goal-based equation and 2) evaluate the accuracy of using the MRTN approach for predicting N rate requirements. Twenty-eight oat N rate response trials were ... J. Clark, D. Karki, A. Bly, P. Sexton |
91. Validating the Wisconsin P Index with Measured Runoff P Losses From Agricultural FieldsPhosphorus (P) indices have been developed by most states in the USA for use as planning tools to assess the risk of P loss and identify appropriate management alternatives to control these losses where needed. Little information is available on the relationshp between P index values and actual P runoff losses in the field. We compared annual P losses in runoff measured at 2 1 field or sub-watershed locations with Wisconsin P index values calculated for the same areas. The research sites include... |
92. Winter Wheat Residue Management Affects Corn Grain Yield and Nitrogen RequirementWinter cereal cover crops are effective in reducing the nitrate-N (NO3-N) leaching from corn (Zea mays L.) and soybean (Glycine max L.) fields. An experiment was conducted as a randomized complete block design with split plot arrangement and four replicates to study wheat (Triticum aestivum L.) cover crop management practices on corn grain yield and nitrogen (N) requirement (economic optimum N rate; EONR). The main plots were four cover crop (CC) treatmen... F. Adeyemi, O. Adeyemi, E. Brevik, A. Sadeghpour |
93. Zone Delineation for Nitrogen ManagementManaging nitrogen through zone soil sampling has been shown effective in revealing residual soil nitrate patterns in North Dakota. Zone delineation has been constructed using several types of data, including yield maps, remote imagery, topography and soil EC sensor data. A study was conducted in North Dakota, Montana and Minnesota to evaluate zone delineation methods. Across the region, yield frequency maps, topography, remote inlagery and soil EC data were effective in helping to construct zon... |