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1. In-season N for Corn Reduced Nitrous Oxide Emissions and Drainage Water Nitrate ConcentrationFarmers want to get the N fertilizer they apply into their crop, not lose it to air and water. This can be difficult to accomplish during wet years when N loss processes are going strong. Applying N in-season can be difficult to accomplish during wet years, but reduces the odds that N will be lost before the crop has a chance to take it up. We compared 2 N management strategies (140 lb N/acre applied pre-plant and variable-rate N applied sidedress based on canopy sensor measurements) and 3 drainage... |
2. Nitrogen and Phosphorus Recalibration for Sunflower in the Northern Great PlainsSunflower producers in the northern Great Plains states of North Dakota, South Dakota, and Minnesota are presently directed to N and P recommendations that originate from research performed in the late 1960s and early 1970s. These three states alone produce more than 80% of the sunflowers in the United States on a yearly basis (USDA-NASS, 2015). The current general formulas determining N and P fertilizer rate in these top-producing states are equivalent. The N recommendation is represented here by... |
3. Nitrogen Timing, Loss, and Replacement... |
4. Cropping System Effects on Phosphorus Response of CornToday's corn producer performs less tillage than in the past and predictions indicate that even less will be done in the future. Changes in management practices involving different tillage and residue incorporation practices alter the dynamics of organic matter turnover in soil and may influence the supply of plant nutrients. To maximize efficiency, it is critical that information be available to guide fertilizer management adjustments for specific tillage and rotation systems. A tremendous amount... |
5. Corn Nitrogen Tests in MissouriExperiments were carried out in farmer fields starting in 1995 with the objective of evaluating or developing field-specific tests to optimize N fertilizer rates for corn. Because some of the soil nitrate tests seem to work differently when manure or alfalfa is in the cropping system, most farms had pairs of experiments, one with an organic N source and the other with none. Descriptions of the experimental locations are given below. Location 1 2 Year 1995 1995 1995 1995 1995 PROCEDURES Countv Callaway... |
6. Predicting N Fertilizer Rates for CornSixteen N rate experiments were carried out in farmer fields in 1995 and 1996. The objective was to measure optimum N fertilizer rates and see whether they could be reliably predicted ahead of time. Yield response to N was measured in each experiment along with soil N measurements (planting and sidedress), and tissue N and chlorophyll meter reading at sidedress time. A very wide range of economically optimum N fertilizer rates was found, fairly evenly spread from 0 to 200 Ib N/acre, with an average... |
7. Alfalfa Response to K Rate, Source and Time of ApplicationThe potassium (K) requirement of alfalfa is greater than that for any other nutrient. Potassium influences several systems within-alfalfa plants, including enzyme activity, carbohydrate production and transport, stomata1 activity: photosynthesis through chlorophyll content and CO, exchange rate, and nitrogen fixation (Munson, 1985). Potassium also markedly influences alfalfa agronomically through yield increases and improvements in forage quality, disease resistance, and overwinter survival. A significant... |
8. Sidedress N applications for corn based on corn colorNitrogen-deficient corn reflects more light over the entire visible spectrum than nitrogen-suff icient corn. Our objective was to calibrate the relationship between remotely-sensed corn color and the nitrogen need of the corn. Corn color measurements were made two ways: Aerial photographs In-field spectral radiometer A successful calibration would allow: Variable-rate sidedress nitrogen applications that precisely meet the needs of the crop. Precise response to in-season N loss (Figure 1). Data reported... |
9. No-till Corn Response to Starter Ffertilizer in MissouriEarly research on starter fertilizer showed that it usually increased early season crop growth, but in Missouri and adjacent states this only occasionally translated into a yield advantage. With widespread changes in tillage practices over the past twenty years, this conclusion may be changing. Recent starter fertilizer trials from other states are frequently showing corn yield responses in no-till systems. Dave Mengel at Purdue University found a yield response to starter in 8 of 11 no-till site-years,... |
10. Effect of Tillage on Legume N Credit to Winter WheatAlthough there has been a significant amount of work done on the availability of legume-nitrogen for corn following alfalfa, several questions have arisen as to the sufficiency and availability of the legume N when winter wheat is raised as a following crop. This is especially true if the wheat is planted soon after the alfalfa is killed. The synchrony of nitrogen released from legumes with crop demand for N has been a concern even with crops such as corn, where N uptake can occur through- out the... |
11. Field Scale Evaluation of Innovative N Management Systems for CornPrevious research has shown that N fertilizer need for corn can vary widely, both between fields and within fields. Producers, however, almost always apply the same N fertilizer rate to whole fields, and vary N fertilizer rates minimally if at all over whole farms. Matching N fertilizer rates more closely to N needs could produce both economic and environmental benefits. Our objective is to test a range of innovative N management systems for their ability to match N rate recommendations to N needs... |
12. Nitrogen Availability, Time of Release and Movement in RotationsPrevious studies have found that N is released through the decomposition of sugarbeet tops (Moraghan and Smith, 1996: Reitmeier et a]., 1999). There is also evidence that N credits may be justified following other broadleaf crops, such as potato and sunflower. This evidence follows work by Vanotti and Bundy (1995) and Bundy et al. (1 993) suggesting that N credits from annual legumes are provided not by decomposition ofthe roots or release ofN directly into the soil from the roots as some might assume,... |
13. Detecting Spatially Variable Corn Nitrogen Needs Using Green Reflectance from 35MM PhotographsRising fertilizer costs and environmental concerns are reasons producers are looking to decrease nitrogen (N) fertilizer rates. This study investigated the use of relative green reflectance fiom 35 rnrn aerial photographs to detect spatially variable corn [Zea mays L.] N needs for developing variable rate fertilizer maps. Photographs were taken at three different growth stages (V7, V11, R3) at altitudes from 3,000 to 5,500 fi for two Missouri fields representing alluvial and deep loess soil types.... |
14. Estimating Second- and Third Year Nitrogen Availability from Dairy manure: It is common practice to repeatedly apply dairy manure to the same fields. To accurately assess the total plant availability of rnanure nutrients, it is necessary to account for the nutrients remaining in soil fiom previous years applications. A corn (Zea mays) field experiment has continued since 1998 on a Plano silt loam. Residual manure N availability was estimated for two and three years after a single rnanure application fiom differences in whole-plant N uptake using 1) fertilizer N equivalence... |
15. Sulfur Responses and the Wisoconsin Alfalfa Sulfur SurveyFor more than 30 years, agronomists, soil scientists, consultants and farmers have recognized the potential for significant responses to applied sulfur fertilizer in northern and western Wisconsin on lighter textured, low organic matter soils that had not recently received manure (Rand et al., 1969; Hoefi and Walsh, 1975; Schulte, 1976; Peters and Kelling, 1987). More recently, crop consultants and others have reported seeing sulhr responses on soils or in locations where they typically were not... |
16. Fertilizer Placement in Fall Strip TillageFall strip-tillage potentially provides an opportunity to increase conservation-till corn yields while sirnplifylng corn planters by minimizing the need for multiple coulters and application of relatively high rates of starter-band fertilizer associated with no-till. However. little is known about the relative efficiency of P and K application using fall strip-till systems co~npared to when starter-band applied in no-till systems. The objectives of the research reported in this study were to evaluate... |
17. Updating General Fertilizer Nitrogen Recommendations for Corn in OntarioCorn yield response data from field trials conducted over the past 30 years which evaluated yield response to fertilizer nitrogen (FN) in Ontario were cornpiled and reanalyzed in order to update general FN recommendations for corn in Ontario. The primary objectives of the reanalysis were to 1) determine the impact of the quadratic plateau model on FN recommendations and 2) develop a set of general recommendations that are free of adjustments based on geographical regions. The new proposed recommendations... |
18. 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. Additional... |
19. 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 of... |
20. Strip-Tilled Corn Responses to Deep Placement of Phosphorus and Potassium- 2005 UpdateReduced tillage systems modify some of the most important variables related with the plant-soil- weather environment and consequently affect the last expression of this relation: yield. A possibly more restrictive root growth scenario (due to lower soil temperatures and higher mechanical impedance), as well as pronounced horizontal and vertical stratification in nutrients within the soil profile (particularly for no-till systems) could lead to a reduction in root uptake of nutrients. This situation... M. Cánepa, T.J. Vyn |
21. Aerial Photographs to Guide Corn Fertigation DecisionsCorn producers with pivot irrigatio n have the potential to apply in-season nitrogen (N) fertilizer much more easily than their non-irrigated counterpa rts. A demonstration project was initiated in 2006 to take advantage of this potential. One advantage for in-season N application is that the risk of N loss prior to crop uptake is minimal. Another advantage is the opportunity to diagnose N n eed. A range of studies have shown that N need can vary widely from one field to another, as well as within... |
22. Using Reflectance Sensors to Predict Nitrogen Needs of CottonObjectives 1) Develop on-the-go N recommendations based on analysis of the reflectance sensor readings. 2) Determine the sensor model, height, and wa velength that give the best prediction for sidedress N. 3) Determine the best growth stag e for sensor-based sidedressing Relevance There is great spatial variability of N in the soil. Cotton fields that receive a blanket rate of nitrogen, ignoring the vari ability, will have areas of excessi ve growth. This unnecessary growth raises production cost... |
23. Effects of Glyphosate Application and Manganese Fertiization on Leaf Manganese Concentration and Yield of Glyphosate-Resistant SoybeanGlyphosate-resistant (GR) soybean is widely accep ted in the United States. Recent research in Indiana and elsewhere has observe d that post-emergence foliar applications of glyphosate may cause or exacerbate manganese (Mn) deficiency and then limit yield of GR soybeans on low Mn availability soils. The objectives of this study were to 1) better understand how glyphosate application(s) might reduce the up take and translocation of Mn in GR soybean plants, and 2) determine the effectiveness of starter-banded... |
24. Plant Density Consequences on Nitrogen Uptake Dynamics of Maize Plants from Vegetative to Reproductive StagesThere are few studies to date that have inte nsively examined the simultaneous effects of differences in plant crowding and fertilizer N availability for different hybrids and locations on N uptake and maize (Zea mays L.) grain yield. The main research objective was to utilize a quantitative framework to bett er understand the physiological mechanisms that govern N dynamics in maize plants at varying plant densi ties and N rates. Two field experiments involving paired near-isogenic hybrids (i.e.... |
25. Corn Plant Uniformity Following Shallow NH3 Placement in Precision-Guided, Pre-Plant Nitrogen ApplicationsCorn (Zea mays L.) production relies extensively on different types of N fertilizers, and anhydrous ammonia (NH 3) continues to be a dominant N s ource in much of the Corn Belt. Timing and placement of NH 3 fertilizer can affect plant-to-plant uniformity and yield of corn, and especially so when high N rates are applied and there is little time between spring pre-plant NH 3 application and planting. The effects of shallow pre-plant NH3 placement on corn plant-to- plant uniformity were investig ated... |
26. Consequences Of Shallow NH3 Placement And Timing On N Use Efficiencies In Corn ProductionA field study in west-central Indiana was conducted to investigate the effects of shallow anhydrous ammonia (NH 3) placement and timing on N use efficiencies in a conventionally tilled corn production system following soybean crop. The spring NH 3 was applied either pre-plant (6- inches offset from future corn row) or side-dress (at mid-row position) at different rates (0, 80, 130 or 180 lbs N acre -1). Aboveground biomass harvest and combine harvested yield were used to determine N recovery, N internal... |
27. Crop Sensor-Based N Rates Out-Performed Producer-Chosen N RatesOptimal N fertilizer rate for corn (Zea mays L.) and other crops can vary substantially within and among fields. Current N management practices do not address this variability. Crop reflectance sensors offer the potential to diagnose crop N need and control N application rates at a fine spatial scale. Our objective was to evaluate the performance of sensor-based variable-rate N applications to corn, relative to constant N rates chosen by the producer. Fifty-five replicated on- farm demonstrations... |
28. Soybean Production Research: A National ApproachU.S. soybean growers are looking for alternative methods to increase soybean yields and recent increases in commodity prices have given producers more freedom to invest in additional crop inputs or products. Unfortunately, quality data from studies addressing multiple contemporary inputs is scarce. The objective of this work was to evaluate the effectiveness of combined soybean inputs on seed yield. These high input systems were tested in six states to evaluate their value across a broad geography.... |
29. Active-Optical Reflectance Sensing Evaluated for Red and Red-Edge Waveband SensitivityUncertainty exists with corn (Zea mays L.) N management due to year-to-year variation in crop N need, soil N supply, and N loss from leaching, volatilization, and denitrification. Active-optical reflectance sensing (AORS) has proven effective in some fields for generating N fertilizer recommendations that improve N use efficiency. However, various sensors utilize different wavebands of light to calculate N fertilizer recommendations making it difficult to know which waveband is most sensitive... G. Bean, N. Kitchen, J. Camberato, R. Ferguson, F. Fernandez, D. Franzen, C. Laboski, E. Nafziger, J. Sawyer, P. Scharf, J. Schepers, J. Shanahan |
30. Corn, Rye, and NitrogenThe U.S. still has an erosion problem. Half of the topsoil is gone over much of the Midwestern U.S., and erosion continues at an unacceptable rate. Protecting soil after soybean is grown is the weakest link in the chain because soybean leaves so little residue that even with no tillage the soil is vulnerable. Cover crops offer great promise to solve this problem. Rye is cheap, hardy, grows well in cool fall weather, and is easy to kill, but evidence continues to mount that rye causes yield loss... P. Scharf |
31. Corn Yield Response to Sub-Surface Banded Starter Fertilizer in the U.S.Sub-surface fertilizer application at planting (i.e., starter fertilization) is a common practice in U.S. corn (Zea Mays L.) production to improve early-season nutrient uptake, nutrient use efficiency, and plant growth, especially under cool and moist spring soil conditions. However, yield increases from starter applications can vary across production systems and environments. Here, we use a meta-analysis approach to quantify and generalize corn yield responses to sub-surface starter... D. Quinn, C. Lee, H. Poffenbarger |
32. Potassium Fertilizer Rate and Timing in Strip-till Systems: Recent Indiana Research with an Alternative K SourceIncreased adoption of conservation tillage systems and alternative potassium (K) sources (e.g., Aspire™, 0-0-58(K2O)-0.5(B)) has prompted new questions about optimal K fertilization practices in maize. The primary goal of this study was to address farmer questions related to strip-till timing, banding Aspire™ with strip-till versus other tillage/placements (e.g., broadcast in no-till (NT) and fall chisel (FC)), and whether reduced K fertilizer rates can maintain maize yields... L.E. Schwarck, T.J. Vyn |
33. Corporate Sustainability Initiatives and Their Interface with Crop Nutrient ManagementAn increasing number of corporations are establishing sustainability initiatives. For ag/food companies, these interface with nutrient management mainly via nitrogen—a lot of carbon dioxide is produced during nitrogen fertilizer manufacture, and some nitrogen fertilizer is converted to nitrous oxide (a potent greenhouse gas) after application. A corporate sustainability representative, a nitrous oxide expert, and a farmer will present their views and then take questions... P. Carter, R. Sirolli, G. Robertson, M. Hora |
34. 35 years of nitrogen researchThis presentation will hit the high points of 35 years of nitrogen research in corn, wheat, and cotton, focusing mostly on timing and rate. With all three crops, applying no N early did not hurt yield—thus no benefit to splitting N. Exception is wheat with low tiller density at greenup, which needs early N Later N applications often gave higher yield than earlier applications for corn and wheat. When... P. Scharf |
35. Comparison of Wheat and Barley to Rye As a Cover Crop for MaizeCover crops are used by farmers in Kentucky to prevent soil erosion and uptake residual nitrogen in between growing seasons of cash crops. Cereal rye has become a popular cover crop due to its sizeable biomass production and superior nitrate uptake ability. Wheat and barley have similar fibrous root systems and may have value as a cover crop. A field study was conducted at the University of Kentucky North Farm in Lexington, KY, in 2021 and 2022. The objectives of this study were to determine if... R. Nalley, C. Lee |
36. Comparison of Wheat and Barley to Rye as a Cover Crop for CornWinter cereal cover crops have become an essential management practice for sustainable corn production. Rye is the most popular winter cereal for cover crop, but wheat and barley may provide a comparable value due to their similar fibrous root systems. Winter cereals provide organic matter, scavenge residual nutrients, and protect the soil from erosion. Winter cereals can immobilize nutrients for the corn crop and can reduce corn stands in some situations, reducing corn yield. The primary objective... R. Nalley, C. Lee, H. Poffenbarger |
37. Effect of Barley and Winter Pea Cover Crops on Nitrogen Availability in No-Till CornCover crops are known to have positive effects on soil health and reduce erosion. However, popular cereal grains used as cover crops, such as rye (Secale cereale), wheat (Triticum aestivum), and barley (Hordeum vulgare) can negatively affect nitrogen availability for the subsequent corn crop. Legumes, such as winter peas (Pisum sativum) could reduce competition for nitrogen between the cereal cover crop and the summer corn crop. This study's objective is to determine if barley as a cover crop... E. Marsh, C. Lee |
38. 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 main... E. Marsh, C. Lee |
39. 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 observed... A. Mutter, C. Lee |