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1. Comparative N and Dry Matter Dynamics in Corn Ears, Stems, and Leaves During the Critical Period After Early and Late-split Sidedress NThere is currently great interest in the possible agronomic and environmental benefits of split N applications that include a late vegetative sidedress timing. The objective of this study was to determine the impact of N rate and timing of N application on the accumulation of N and dry matter in the ears, stems, and leaves of corn during the critical period (encompassing the period two weeks before to two weeks after silking) in order to understand the differing sensitivity to N stress in these... S. Mueller, T. Vyn |
2. Nitrogen Fertilizer on Soybeans: Are We Making Progress?The recent drop in the price of soybeans has dampened enthusiasm for applying inputs of uncertain value to crops, but application of fertilizer N during the season is often reported by soybean yield contest winners as a way to increase yields, and some producers have adopted this as a practice. As soybean yields have increased, the amount of N required by the crop has increased. Soybean seed with 36 percent protein is about 5.75% N, and a bushel of soybean grain contains about 3 lb.... E. Nafziger, J. Vonk |
3. Micronutrients Fertilization for Corn and Soybean: A Research UpdateEssential plant nutrients such as boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn), and others are absorbed by crops in very small amounts and are referred to as micronutrients. A deficiency can have a large impact on crop yield, however, because they perform important physiological functions. The soil parent material and soil formation processes over time along with effects of soil moisture, aeration, and temperature can significantly influence the amount of plant-available... |
4. Minnesota Long-Term Phosphorus Management Trials: Phase I, The Build PeriodPhosphorus (P) fertilizer recommendations are usually made using one of two philosophies, Build and Maintain or Sufficiency. In recent years, the Sufficiency approach has been questioned because of concerns of reducing soil test levels and yield sustainability and whether it has the same yield potential as the Build and Maintain approach. Trials were initiated in 2010 at six locations across Minnesota to develop various soil test P Interpretation Classes in replicated experiments. The initial phase... |
5. Corn Nitrogen Rate Response and Crop Yield in a Rye Cover Crop SystemWater quality impairment related to N loss from crop production fields continues to be a concern in Iowa, including meeting the USEPA nitrate-N drinking water standard and reducing N export to the Gulf of Mexico. Therefore, in-field production practices would be helpful to aid in reduction of nitrate leaching and movement to water systems. One practice identified in the science assessment for the Iowa Nutrient Reduction Strategy is use of a winter cereal rye (Secale cereal L.) cover crop, where a... |
6. Effect of Three Tillage Systems on Soil Bulk Density and Porespace DistributionMany grain producers in Kentucky use a 3 crop in 2 year rotation of corn fol lowed by small grain-soybeans, and commonly no-ti1 1 the soybeans and corn in order to intensively use sloping land for continuous grain production. Because of the intensity of machinery traffic in this system, grtwxs. are concerned that continuw no-till management may cause compaction, and that such fields may need occasional primary tillage. In order to obtain information regarding this situation, we conducted a test for... |
7. Studies of Agricultural Effects on Groundwater Quality in KentuckySeveral small watersheds and tiled fields have been selected in Kentucky to assess the influence of agricultural practices on groundwater quality. Sites were selected to represent the dominant agricultural systems used in the most agriculturally important areas of the state. Within each study site, water samples from springs, wells, streams, or tile lines are being sampled monthly to monitor content of N03-N, atrazine. alachlor, and fecal bacteria. Although sampling will continue for at least another... |
8. Use of A Wheat Cover Crop to Trap Residual Soil N for No-till CornIn continued work on long-term no-till plots, wheat was tested as a winter cover crop to determine how much carryover soil N it would accumulate from the preceding no-till corn crop and make available to the successive no-till corn crop. Wheat biomass at time of planting no-till corn was about 1.7 times greater following 240 lbs N/A on the preceding corn than following 80 lbs N/A. However, maximum wheat biomass was only about 1 T/A, and contained only 15 lbs N/A more than wheat grown following corn... |
9. Alternative Approaches to Making Fertilizer RecommendationsThe objective of this research project was to evaluate, both agronomically and economically. some common altcrnative methods of making fertilizer recornmcndations for corn, soybeans, and soft-red winter wheat used in Indiana. Over a period of six years ( 1992- 1997) the effect of seven alternative fertilizer recommendation philosophies on soil test levels, crop yields, plant tissue analysis, and fertilizer additions were measured in an attempt to determine differences in performance between these... |
10. Basic Concepts of Soil Acidity and LimingMost midwestern soils require periodic applications of aglitne or other liming materials for optimum crop production. Liming has several beneficial effects: I ) it reduces harmhl or potentially tosic conditions which can develop in acid soils; 2) it increases the availability of some of nutrients: 3) it replaces the supply of calcium and magnesium essential for plant growth which is depleted as soils become acid; 4) it ensures favorable conditions for the activity of certain herbicides; and 5) it... |
11. A Field Study of Soil Test Variability, Its Effects on Accuracy of Fertilizer Recommendations, and the Subsequent Effect of Variable Rate Fertilizer Application on Soil Test ValuesThree 2.5 acre blocks were selected for intensive soil sampling from within an approximate 90 acre field which had been partitioned into 35, 2.5 acre blocks by a farm supply dealer. The 2.5 acre blocks had previously been sampled on a central composite grid basis and a variable rate fertilizer spreader (VRS) programmed for fertilizing the field. Three other more intensive sampling techniques were used to sample the 3 blocks selected for more detailed studies. Results obtained showed that soil test... |
12. Challenges for making intensive soil sampling and VRT Pay. Ongoing Iowa Studies with PhosphorusSoil fertility evaluation and management can be greatly improved with the use of precision agriculture technologies. Differential global positioning systems @GPS), yield monitors, various forms of remote sensing, geographical information system (GIs) computer software, and variable rate technologies are available for use to producers. Intensive soil sampling, crop scouting, and other practices complete the new technological package. Soil testing is a diagnostic tool especially adapted for site-specific... |
13. Corn and Soybean Response to Potassium Fertilization and PlacementI\ncreased adoption of conservation tillage, evidence of large within-field nutrient variability, and an apparent increase in the Frequency of crop potassium (K) deficiency symptoms in Iowa and other states have prompted questions about the effectiveness of current soil-test K interpretations and fertilizer recommendations. These questions relate to fertilizer placement and management of within-field nutrient variability. Broadcast placements are less costly than banded placements but they seem inefficient... |
14. Evaluation of the Amino Sugar-N Based Soil test in Iowa Corn ProductionAn important improvement in estimating economic N applications for corn production would be to predict the soil N supply capacity each year. The objective of this research is to evaluate the adaptability and potential calibration of the amino sugar-N based Illinois N Soil Test in corn production fields across diverse Iowa soils. Nitrogen rate trials were conducted at multiple sites over several years, many on producer fields. Soil samples were collected at 0-6 and 0-12 inch depths in the fall and... |
15. Providing Flexibility in P and K RecommendationsHistorically, land grant Universities have generally provided a single rate recommendation for nutrients such as phosphorus (P) and potassium (K). Depending on the particular University in question, these nutrient rate recommendations are generally based on two widely recognized approaches to managing soil and fertilizer P and K - the nutrient sufficiency approach and the build-maintenance approach. The goal of a nutrient sufficiency based soil fertility program is to apply just enough P andior K... |
16. 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. The... |
17. Value of Tillage Practices and Nitrogen Rates for Corn ProductionMost N recommendations for corn (Zea mays L.) production in the U.S. Midwest do not consider tillage as a factor when an appropriate N rate is determined. Our objectives were to determine the response of grain yield and RTN to increasing rates of fertilizer N for corn grown in three tillage systems. Tillage by N rate experiments we re conducted at eight Central Illinois site-years at three locations and years (1998-2000). Tillag e systems employed were: zero-till, where no tillage was performed at... |
18. 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... |
19. Triple-Stacks, Genetics, and Biotechnology in Improving Nitrogen Use of CornGenetic improvement in N use efficiency (NUE) is a clear strategy fo r enhancing yield and fertilizer N management of corn ( Zea mays L.), and has been the subj ect of our ongoing research. Calculation of the N requirement (N fertilizer usage/grain yield) based on statewide average grain yields and fertilizer sales shows a stead y decrease since the mid 1980's, suggestive of a genetic improvement in N use. Direct comparis on of the response to N for a 1980�۪s hybrid with its modern counterpart... |
20. Evaluation of Novel Soybean Inputs to Enhance YieldThe U.S. Average soybean yield was 43.5 bushes/acre in 2010 (www.nass.usda.gov), with reports of much higher yields in some areas. With large yield differences among years and locations, as well as some high-profile marketing and publicity campaigns promoting 'high yield' management, producers are interested in any inputs or management practices that might improve yields. High soybean prices at present and interest in finding ways to increase yield have led to emergence of a number of new products,... |
21. Recoverable Yield: A New Component for Improving Algorithms Used For Sensor Based Nitrogen Management In WheatIncreased interest in N management over the past decade has stimulated interest in using optical sensors to predict N needs in a number of crops. Many universities have created N recommendation algorithms for winter wheat, with slightly differing approaches. While many university algorithms operate under the assumption that 100% of the yield potential difference between the N rich strip and the farmer practice can be recovered, we believe that this will not always be possible. The objective of this... |
22. Assessment Of Enhanced Efficiency Urea Products On Maize In MissouriUrea is the most commonly used N fertilizer worldwide, but can be easily lost to the environment through ammonia volatilization. Enhanced efficiency fertilizers (EEF) have been developed to help prevent these losses. Field studies were conducted from 2009 to 2011 on a Mexico silt loam (fine, smectitic, mesic, Vertic Epiaqualf) to determine the efficacy of five EEF urea products compare to untreated urea when surface applied to no-till maize (Zea mays L.). Treatments included untreated urea, Agrotain,... |
23. The Effect of Agricultural Management Practices on Labile Soil Carbon and Nitrogen in WisconsinAmid ever-increasing enthusiasm for soil health there remains uncertainty about how best to measure it, to interpret the results, and to adapt agricultural management accordingly. One factor of particular interest to farmers is the capacity of a soil to mineralize organic matter, making nutrients available to crops. This research takes a survey-based approach to identify how labile carbon (C) and nitrogen (N) – as permanganate oxidizable carbon (POxC), potentially mineralizable carbon (PMC)... G. Richardson, M. Ruark, E. Silva, M. Chawner, E. Olson, A. Radatz, C. Zegler |
24. Nitrogen Fertilizer For SoybeanConcern about soybean’s ability to provide energy to fix adequate N while still producing high yields has led to renewed interest in in-season use of N fertilizer. We conducted a series of fertilizer N timing experiments in Illinois, in different soil types with a range of yield potential. There were few responses to N in silt loam soils, with unfertilized check yields ranging from 4,108 to 6,125 kg/ha, though applying the same N increment four times increased yield significantly... J. Vonk, E. Nafziger |
25. Manure, Phosphorus, and 125 Site-Years of Edge-of-Field Runoff MeasurementsPhosphorus export from agricultural fields continues to create water quality concerns in Wisconsin. The UW Discovery Farms program, along with Discovery Farms Minnesota have collected 125 site-years of edge-of-field monitoring datawhich can be used to better understand the relative effects of inherent soil properties (slope, drainage class, texture), management practices (manure application, tillage, crop rotation, cover cropping), and soil test P values on seasonal (frozen and non-... M. Ruark, A. Thompson, Z. Zopp, T. Radatz, A. Radatz, E. Cooley |
26. Exploratory analysis of event-based edge-of-field phosphorus lossesUnderstanding how the timing of management activities, particularly manure and fertilizer applications, impacts P losses in runoff can improve farmers’ decisions on when to apply nutrients. The University of Wisconsin Discovery Farms and Discovery Farms Minnesota have been monitoring edge-of-field nutrient losses since 2004. This data set includes over 125 site-years of runoff across 26 fields and includes 1574 individual runoff events. The objectives of this study are to: (i) determine... |
27. Grain Yield and Nutrient Removal Relationships in High-yield Modern Corn Hybrids Under In-season Sulfur and Potassium ApplicationsAdvancements in modern corn genetics and adoption of intensive management practices, including in-season sulfur (S) and potassium (K) applications, have helped corn farmers set higher yield goals while prompting new questions about plant nutrient dynamics during the season and cumulative nutrient removal with grain at harvest. The primary goal of this study was to investigate how hybrid and fertility management decisions in situations with high yield potential (>225 bushels acre-1) impact plant... G. Verhagen, T. Vyn |
28. Managing Trade-offs of Winter Rye As a Cover CropWinter rye (Secal cereale L.) is a commonly used cover crop in Wisconsin due to its effectiveness in reducing soil erosion, scavenging nitrogen, and improving soil health. However, the potential trade-offs of using grass cover crops are decreases in corn yield driven by nitrogen uptake and immobilization. The study aims to determine the single year effect of rye seeding rate on rye biomass and optimum nitrogen rate of the subsequent corn (Zea mays L.) crop, while also... M. Schauer, M. Ruark |
29. Cover Crops, Manure, and NitrogenFall seeded cover crops can offer soil and water conservation benefits to dairy-based cropping systems. However, uptake by these fall cover crops can also limit nitrogen availability from the manure to the next crop. Field research projects throughout the state of Wisconsin have been conducted to assess how cover crop specie, biomass, and N uptake influence the amount of supplemental N needed to fertilize the following corn crop to maximize yield. Fall seeded cover crops that winter kill (spring... M. Ruark, A. Waggoner |
30. Effect of Long-Term Tillage and Crop Rotation on Mineral Associated Organic Matter Distribution Along the Soil ProfileSoil carbon (C) stability in soil organic matter (SOM) is critical for mitigating climate change as well as for providing food security. SOM associated with mineral Mineral-associated organic matter (MAOM) has a longer residence time than the light, sand-sized particulate organic matter (POM). Therefore, it is important to study the effect of conservation practices like no tillage and crop rotation on MAOM distribution to better understand carbon stability and persistence. The objective of this... A. Gautam, T. Vyn, S. Armstrong |
31. 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 field-by-field... M. Schauer, M. Ruark |