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1. Independence of Crop Yield and Nitrogen Rate Across SitesHistorically soil fertility specialists in the North Central States of the USA have constructed nitrogen (N) rate recommendations based on ‘yield goals’ or ‘expected yield’. Within the past ten years, there has been a general realization by soil fertility researchers that within a site or field there is a relationship between N rate and yield; however, because of soil and weather differences between sites there is no relationship in N rate studies with a large number of... D. Franzen, L. Sharma, H. Bu, E. Schultz, J. Breker, A. Denton |
2. Project Sense: Sensors for the Efficient Use of Nitrogen and Stewardship of the Environment. An On-Farm Research Effort to Increase Adoption of Sensor Based N ManagementLow nitrogen use efficiency (NUE) has been attributed to several factors including asynchrony between nitrogen (N) fertilizer application, crop demand, and spatial variability (Shanahan et al., 2008). Sidedress applied N synchronizes crop uptake demand for N, but does not address the spatial and temporal variability that exists in a field year to year. Active crop canopy sensors provide an ability to monitor and respond to spatial and temporal N variability for a given field. A three-year project,... B. Krienke, R. Ferguson, J. Luck, L. Thompson, J. Parrish, N. Mueller, T. Mieno, J. Crowther, T. Shaver, T. Ingram, D. Krull, K. Glewen |
3. Corn Nitrogen Evaluation in South DakotaCurrent Nitrogen (N) recommendations for corn in South Dakota use an N rate calculator approach (yield goal x 1.2 ⤓ soil test Nitrate-N (0-2 ft) ⤓ legume credits ⤓ other credits such as manure application or N in starter fertilizers + 30 lbs N/a for no-till). The N coefficient has been modified in the past from 1.45 in 1975, to 1.3 in 1982 and currently 1.2 determined 1991. The N coefficient is in dire need of re-evaluation because... A. Bly, S. Berg, P. Sexton, R. Gelderman |
4. Crop Sensors as In-season Nitrogen Management Tool for Winter Wheat in WisconsinIn Wisconsin, current winter wheat (Triticum aestivum L.) nitrogen (N) rate guidelines are determined by soil type, previous crop, and pre-plant soil nitrate test (PPNT). Nitrogen management may be improved through site-specific assessments of N need in the spring, offering a more effective use of top-dressed N. The study objective was to determine if crop reflectance measurements could be used to determine optimal in-season N rates on silt loam soils in eastern Wisconsin. This study evaluated the... |
5. Improving Alfalfa Production in Wisconsin with Sulfur and Potassium FertilizerThe longevity and quality of an alfalfa stand is an essential component for Wisconsin�s dairy rotations. A study was developed to determine the effects of sulfur and potassium applications on the growth and development of alfalfa stands. The objectives of this study were to determine the effect of i) S fertilizer rate, timing and form on alfalfa yield, ii) recommended or no K fertilizer application on alfalfa yield on soils testing optimum or low for K, and iii) S and K application on soil test... |
6. The Effect of Tillage and Soil Test and Applied K on Corn and Soybean ProductionThe buildup-maintenance fertility concept for P and K has a strong theoretical basis, but much of the research from which it was derived was not designed to accurately determine the true maintenance requirement. Most of that research was confounded by an annual application at set rates irrespective of yield obtained. Experience in recent years has shown that on some soils the K soil test has not consistently accounted for past additions of fertilizer. In addition, applications equivalent to crop... |
7. Grid Sampling or Topography Sampling for Soil NutrientsSite-specific application of fertilizers uses field soil sampling for its information basis. Many fields are currently sampled using a grid approach. In North Dakota, examination of grid sampling showed nitrate-N to follow topographic patterns in a field, allowing the possibility of less intensive sampling for N. Reviewing previous grid sampling work in Illinois, some soil properties may be associated with landscape features, including nitrate-N in the surface 6 inches and soil pH. However, Illinois... |
8. Site-Specific Prediction of Soybean Nitrogen ContributionsSoybean has long been recognized for its nitrogen (N) contributions and yield enhancing effects in crop sequences. Soybean N credits in the Midwest range fiom 20 to 40 Ib of Nlacre (Kurtz et al., 1984). Several Midwestern states recommend a legume credit of 40 Ib of Nlacre following an average crop of soybean. Current Wisconsin recommendations suggest a reduction in nitrogen fertilizer rates for corn following soybean of 1 Ib N hushel of soybean yield up to a maximum credit of 40 Ib Nacre (Kelling... |
9. Assessing the Illinois N Test as a Decision Management Tool for SugarbeetThe Illinois nitrogen soil test (INST) was developed to detect sites where corn is nonresponsive to nitrogen (N) fertilization. Nitrogen managernent is critical for sugarbeet production because sucrose content can be compromised with excessive applications of N. The objective of this study was to assess the ability of the INST and other parameters (OM, total N, and NO3'-N) to predict N responsiveness in sugarbeet. Yield and RWSA response to N was assessed at five sites each in 2002 and 2003. INST... |
10. Evaluation of the Illinois Soil Nitrogen Test in the North Central RegionData from 96 locations across the North Central Region was complied to evaluate the usefulness of the Illinois soil nitrogen test (ISNT) in identifying fields where corn will not respond to additional N fertilizer and predicting the yield optimizing N rate (YONR) for each field. The ISNT could not accurately predict non-responsive sites, nor could it predict YONR. Sub-setting the data based on soil drainage class and previous crop did not improve the predictive capability of the ISNT. The ISNT was... |
11. Silage Specific Corn Hybrids for Silage Production in KentuckyFour corn hybrid types at three plant densities and two nitrogen rates were evaluated for forage yield, forage quality and ensiled quality. The four hybrid types included nutri-dense (ND), waxy (WX), leafy (LF), and dual-purpose (DP); while the three target plant densities were 54 000, 68 000, and 81 000 plants ha; and the nitrogen rates were 134 and 224 kg ha". WX consistently had low forage and grain yields compared with the otl~er types. When averaged over nitrogen rate and hybrid: plant density... |
12. Weed Control Timing Effects on Corn Yield Response to NitrogenNitrogen (N) rate guidelines for corn are under c ontinued scrutiny to maximize N use efficiency in order to minimize potential N losses to th e environment while maximizing economic returns to growers, especially with significant N fertilizer price increases in recent years. In-season crop stress can potentially affect corn N needs for optimum production. Recently, postemergence weed control has become more common with th e availability of glyphosate resistant corn hybrids. Delaying weed control... |
13. Effects of Sampling Time, Soil Moisture Content, and Extractant on Soil Test Potassium LevelsAn accurate prediction of plant-available pota ssium (K) requires a thorough understanding of the mechanisms that might impact soil test K. A three year field study was developed to determine relationships between soil test potassium (STK) levels and time of soil sampling, soil moisture content, and extractant. Five field sites were established in 2006 throughout Wisconsin at Arlington, Hancock, Marshfield, and Lancaster Agricultural Resear ch Stations, and a private farm in Fond du Lac county each... |
14. Nitrous Oxide Emissions From Nitrogen Fertilizers In IllinoisNitrous oxide (N 2O) has a large global warming potential (GWP). Agricultural applications of nitrogen (N) contribute to N 2O emissions but it might be possible to mitigate such emissions through different N sources. We investigated the potential for anhydrous ammonia (AA), urea, and polymer coated urea (ESN) to mitigate N 2O emissions while enhancing corn (Zea mays L.) production. This three-year study was conducted in Champaign County, Illinois on highly productive mollisols during 2009 to 2011.... |
15. Minimizing Nitrate Loss from Manure-amended Wisconsin Sandy SoilsThe impact of dairy manure application on nitrate leaching was evaluated at two sites with no manure history. Manure treatment (separated-solid manure, separated-liquid manure, separated- liquid manure plus a nitrification inhibitor, and two treatments with no manure) was the main plot. Each manured plot was split into six subplots with three receiving a single sidedress fertilizer application of 0, 56, or 112 kg N ha -1 while the others had two sidedress applications totaling 112 kg N ha-1 with... |
16. 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 greenhouse... A. Beltrame, C. Penn, D. Quinn, M. Williams, C. Zhang |