Proceedings
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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. 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... |
5. 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... |
6. 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... |
7. 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,... |
8. 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... |
9. 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.... |
10. 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... |
11. Tank-Mixing Micronutrients Fertilizers with Glyphosate- Potential Problem or Efficient SolutionsTANK-MIXING MICRONUTRIENT FERTILIZERS WITH GLYPHOSATE - POTENTML PROBLEM OR EFFICIENT SOLUTION Mark L. Bernards, Kurt D. Thelen, Donald Penner Michlgan State University, East Lansing, MI Summary: Many agribusinesses are currently promoting the application of micronutrient foliar fertilizers in tank-mixtures with glyphosate for increased efficiency in glyphosate-resistant soybean production. This practice is inconsistellt with data which shows decreased glyyhosate efficacy in the presence of the hard-water... |
12. 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... |
13. 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... |
14. 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... |
15. 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... |
16. 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... |
17. Nitrogen Management: Unraveling the Effect of Timing and FormImprovement of nitrogen use efficiency by co rn production would decrease the potential for nitrogen loss into the environment. A study ha s been conducted in Ames, Iowa on 16 different forms and rates of nitrogen in both a continuous corn and corn-soybean production systems. There were differences among treatments; howeve r, the most consistent treatment was the SuperU applied as a 150 lb A -1 preplant or as 50 lb A-1 preplant and 100 lb A-1 sidedress and UAN with Agrotain adde d to both the 50... |
18. 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... |
19. 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 |
20. 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 |
21. 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 |