Proceedings
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1. A New Frontier Below the Horizon: My Work with Pivot Bio BiologicalsSymbiotic Nitrogen (N) fixation is an amazing process that harnesses the power of two organisms (a legume and rhizobium) to mutually benefit one another. However, the process of biological N fixation or the reduction from dinitrogen gas to ammonia/ammonium via the nitrogenase enzyme is an expensive one. The relationship between host plant and rhizobium hinges on the free exchange of N for carbon and other metabolites. Nitrogen fertilizer is often the most limiting nutrient for cereal crop pro... T. Roberts |
2. Agronomic Evaluations of MAP and DAPThe old issue of MAP vs DAP has resurfaced. Although the renewed interest in this issue stems from manufacturing considerations, it would seem appropriate at this point to review our current understanding of agronomic characteristics of these two materials. One of the last reviews done on this subject was part of a review of P sources written by Larry Murphy and presented at the 1979 North Central Extension Industry Soil Fertility Workshop entitled "MAP, DAP, Poly and Rock. The amount of new res... |
3. Banded Fertility: Music for Higher Corn YieldsThere is a need in production agriculture to reduce nutrient loss to the environment and implement more sustainable production practices, but grower adoption has been slow and inconsistent due to fear of reduced yields and profit. However, if new fertilizer technologies can be used to increase nutrient use efficiency and grain yield simultaneously, grower willingness to adapt environmentally sustainable practices is far more likely. We implemented a two-year corn (Zea mays L.) yield ... S. Foxhoven, F. Below |
4. Biomass and Nitrogen Partitioning of the Modern Russet Varieties of Potatoes Under Nitrogen Stressed and Optimum ConditionsWisconsin is the third largest producers of potatoes in the USA. Nitrogen (N) is the most limiting nutrient in the development of crop biomass and yield. N uptake and partitioning in potato can be different based on the varieties and nutrient availability. These differences can result in the wide variations in yield accumulation and nitrogen use efficiencies. However, there is a lack of quantitative understanding of the in-season N uptake and demand and biomass partitioning of the different v... A. Rawal, M.D. Ruark, R.A. Lankau, J. Ross |
5. Can ProveN Reduce Corn Nitrogen Requirement in Minnesota?ProveN is a microbial product applied in-furrow with the goal of reducing the total amount of nitrogen fertilizer needed for corn (Zea mays L.). Six field trials were established over three growing seasons in Minnesota to evaluate corn response to nitrogen with and without ProveN applied at planting on the seed. Nitrogen was applied as urea prior to planting at five locations and split applied with 1/3 of the total rates of nitrogen applied at -planting, at V4, and V8 growth stages. ... D. Kaiser, J. Vetsch, M. Currie |
6. Can Soil Health Metrics Improve Standard Soil Fertility Recommendations?It is commonly speculated that integrating soil health (SH) testing with soil fertility (SF) testing would improve fertilizer recommendation decisions. However, quantified impacts of SH properties, specifically soil biological properties, on fertilizer demand have not been well established. The objective of this research was to explore corn (Zea mays L.) yield response to phosphorus (P) and potassium (K) fertilization as influenced by established SF analysis and common SH me... C.J. Ransom, J. Svedin, N.R. Kitchen, K. Veum, S.H. Anderson |
7. Chloride from Fertilizer and Water Pollution -Should I Be Concerned?Chloride is a more recently recognized pollutant of concern in many states. In Minnesota, 50 lakes and stream reaches are impaired for chloride, 30% of shallow monitoring wells exceed the secondary health standard, and chloride is on the rise in many other waters. Chloride is toxic to aquatic life, can contaminate groundwater, and has additional environmental impacts. How much does fertilizer contribute? This presentation will cover chloride sources... C. Dindorf |
8. Combining Nitrification Inhibitor TechnologiesTechniques exist for the partial control of nitrification, but few studies have determined the effectiveness of combining more than one technique. A series of experiments compared the nitrification rate of urea granules as influenced by granule size (0.01, 0.1, and 1.0 g/pellet) and dicyandiamide (DCD) addition (0, 1, 2, 5, and 10% of N) . A second series of experiments measured the interactive effects of DCD and ammonium thiosulfate (ATS) on nitrification of liquid fertilizers. Both experiments... |
9. Comparative Effects of Herbicide, Nitrogen Inhibitors and Nitrogen Source on Nitrification and Corn YieldNitrogen management in crops can be challenging due to nitrogen transformations and losses in soil, such as nitrification and denitrification. Nitrification is the conversion of ammonium (NH4+) to nitrate (NO3-) by ammonia oxidizing bacteria (AOB), Nitrosomonas and Nitrobacter. Nitrates can be lost through leaching during heavy precipitation. Nitrification inhibitor products are used to temporarily slow the nitrification process by... W. Neels, A. Jhala, B. Maharjan, R. Little, J. Iqbal |
10. Comparison of Mehlich-3 and Haney H3A-4 Soil Tests in Kansas SoilsRecommended application rates of soil fertility amendments are often based on a soil test in agricultural production systems. Interpretation of these soil tests requires correlation and calibration to crop yield response, nutrient uptake, or existing soil tests. The Mehlich-3 soil test procedure is currently used to evaluate the plant availability of phosphorus (P) and potassium (K) in Kansas soils. However, the Haney soil test has gained attention in recentyear and has been used to adjust so... B. Rutter, D. Ruiz Diaz |
11. Corn Nitrogen Fertilizer Management Practices in Eastern South DakotaThe adoption factors of N best management practices (BMPs) that can lessen N loss needs to be understood to help increase adoption rates. Understanding the local, small-scale factors (geographic location, tillage type, and farm size) that influence the use of N BMPs will help nutrient management professionals provide the research and information needed to increase the use of N BMPs. South Dakota (SD) survey data from 465 producers was used to examine the above local, small-scale factors that ... J.D. Clark, A. Bly, P. Kovacs, J. Ulrich-schad |
12. Corn Response to Phosphorus Fertilization and Evaluation of Soil Test Methods in Kansas SoilsPhosphorus is a critical nutrient in corn (Zea mays L.) production, and limitation in P availability can result in significant yield reduction. The objective of this study was to evaluate corn response to phosphorus fertilization and evaluate multiple soil test methods in Kansas soils. The study was conducted in 13 locations across Kansas during 2021. Fertilizer treatment consisted of five rates of phosphorus (P) fertilizer (0, 30, 60, 90, and 120 lbs. P2O5 acre–1), using mono-... G. Roa , D. Ruiz Diaz |
13. DAP vs MAP Manufacturing/Marketing ImplicationsOver the past several years, discussions on the suitability of monoammonium phosphate (MAP) and diammonium phosphate (DAP) as P sources for crop production have been common. In addition to agronomic principles, these discussions have often focused on what the future holds on the availability of these two materials in the marketplace. This discussion will deal with manufacturing and marketing influences on future availability/use, while agronomic comparisons will be made elsewhere. To some, phosp... |
14. Effect of Date of Planting on Method of P Performance for Winter WheatSeed and knifed P (dual placement) have usually performed similarly on winter wheat (Triticum aestiviuum L.), but in some years seed applications have been found to be superior to knifed P. Three winter wheat experiments were established on low available P soils in southeast Nebraska to study the effect of date seeding on seed and knifed P (dual placement) performance. Three rates of P (11, 22, and 33 kg P ha-') were seed and knife applied on three seeding dates in 1987. Data indicated that the ... |
15. Effect of Liquid Calcium as a Liming Agent in SoilMaintaining proper soil pH is the foundation of a soil fertility program and influences plant productivity, nutrient availability, and herbicide activity. This study was conducted to determine the effectiveness of liquid calcium compared to known liming agents to raise the pH of soil. Test plots that compare liquid calcium to proven liming agents were conducted in 17 counties across the state of Kentucky on cool season annual grass pastures. Two experimental protocols were deve... B. Setchell, E. Ritchey |
16. Evaluation of Soil Test Methods and Early Tissue Analysis to Assess Potassium Response in SoybeanMultiple soil test methods has been evaluated as diagnostic tool for potassium management in soybeans. This study compared different soil test K methods (STK) and evaluate the correlation to soybean yield and K uptake response in low testing soils, and assessed tissue analysis as alternative for in-season correction options. ... D. Charbonnier , D. Ruiz Diaz |
17. Farming the Data: New Paradigm in Precision AgriculturePrecision Agriculture has been around for over two decades. The first decade had a strong focus on quantifying spatial variability in soils, the second decade spent significant time on science and technology of precision management of nutrients. Now, with increasing adoption of Precision management techniques and practices there is interest in harnessing the power of data to grapple the new paradigm of making management decision based on evidence. The success of future farming practices, outp... R. Khosla |
18. Fertilizer Manufacture - Converting Nature's Nutrient Storehouse to Plant NutritionNorth American farmers rely on reliable supply of key fertilizer inputs to maintain productivity and profitability. Nitrogen fertilizers are produced from atmospheric nitrogen gas, while phosphate and potash fertilizers are mined from major North American deposits as well as others around the world. All the major fertilizers are supplied, in large part, by North American producers from domestic production supplemented by some imports from international producers. Nitrogen prod... A. Blaylock |
19. Fertilizer use in the Future- A University PerspectiveOver the last few years, several agrodc, economic, political, environmental and sociological trends have begun to eruerge which will significantly affect fertilizer use in the next decade and perhaps beyond. The wide-spread use of fertilizers is a relatively recent developmt. Over the past 40 years, farmers repeatedly saw the benefits of fertilizer applications and developed a faith in their need. Hwever, the 1990's are not the 1950's. As point& out by Dean L. M. Walsh in a recent paper in Deale... |
20. 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 ... G. Verhagen, T. Vyn |
21. High Gypsum Application Rates Impacts on Iowa Soil Properties, Dissolved Phosphorus Loss, and Crop YieldGypsum (calcium sulfate) is a common sulfur (S) source for crops and rates in the northcentral region seldom are > 250 lb/acre. It is known that even higher gypsum rates do not raise soil pH. Research in eastern or southeast states showed that in some conditions high gypsum rates can improve other chemical or physical properties and can reduce dissolved phosphorus (P) loss from fields. However, little research has evaluated potential benefits in prairie-developed soils of Iowa and the regi... A.P. Mallarino, M.U. Haq |
22. Impact of Site-Specific Variability on the Effectiveness of Active Canopy Sensors for In-Season N Management in CornIn-season nitrogen (N) management in corn guided by active canopy sensors is often associated with higher yields, profit and nitrogen use efficiency (NUE). However, these benefits could vary from field-to-field and year-to-year. These inconsistent relationships between technology and benefits represent a major challenge for increasing adoption of sensor-based N application in corn. Thus, a better understanding of which site-specific factors determine positive benefits from sensor-based N appl... L. Puntel, J. Luck, L. Thompson |
23. Implementation and Validation of the MRTN Recommendation System in WisconsinThe maximum return to N (MRTN) recommendation system for corn was implemented in Wisconsin in 2006. In many ways, MRTN is a dynamic extension of N response-based N recommendation that was implemented in 1991. Vanotti and Bundy (1994) demonstrated the utility of using N rate response trials as the basis for N recommendations. And that grouping soils by N response and soil characteristics was useful could improve N recommendations. In Wisconsin recommendations, relative yield potential was qual... C. Laboski |
24. Implications of Clay Mineral Analysis for Improved Calibration of Corn Potassium Fertilizer RecommendationsEastern South Dakota has seen an increase in soil potassium (K) deficiencies. To correct those deficiencies and avoid yield reductions, corn producers rely on accurate K fertilizer recommendations (KFRs). Among the various parameters used to estimate a KFR, clay mineralogy has significant potential to increase KFR accuracy. The study has two objectives: first, to determine the relationships among clay mineralogy, K uptake by corn, and KFRs, and second, to calibrate KFRs in South Dakota to inc... A. Ahlersmeyer, J. Clark, D. Clay, K. Osterloh |
25. Independence of Yield and N-Rate, and Use of EONR in N Fertilizer Recommendations in North DakotaEvidence for the independence of N-rate and yield comes from the improved relationship of N-rate with relative yield compared to raw yield in corn, spring wheat and sunflower N-rate experiments in North Dakota. Relationships were also improved in corn by grouping experiments by regional location and whether the soils are high clay (>40% clay) or not, and discriminating between long-term no-till (6 years or more continuous no-till) or conventional till. In spring wheat, regional differences... D. Franzen, H. Bu, L. Sharma, E.C. Schultz, A. Wick, B. Goettl, M. Berti |
26. Integrated Farm Management Demonstration Program in IowaThe Integrated Farm Management (IFM) Demonstration Program was established by the landmark 1987 Iowa Groundwater Protection Act. The five-year program, funded through 1992, is a cooperative effort involving various state agencies, Iowa State University and Iowa farmers. The program coordinators, many of whom are Iowa State Extension Service staff and scientists, work with farmers to help them implement best available technology that protects the environment and conserves energy. The goal of the ... |
27. Maize Yield Increased by Optimal Timing and Placement of Polymer-coated Nitrogen FertilizerNitrogen (N) fertilizer application timing and placement can manage N availability to improve maize (Zea mays L.) productivity, but polymer-coated N fertilizer offers a different approach to season-long N availability and creates new N management opportunities. The objective of this study was to compare the effectiveness of conventional and polymer-coated N sources across fertilizer timing and placement combinations to optimize maize productivity. Field trials were conducted at three... S. Schwartz, F. Below |
28. Managing Field Soil Fertility VariationsFertilizer and crop production inputs are most often applied as a single blanket application rate across an entire field. Yet variations in field conditions including soil characteristics and measured crop yield are known to exist and often in a systematic, fashion. Grid soil sampling for fertility variations, plant analyses, and color photography were found to be most useful tools for assessing manageable field variations. Increased profit and environmentally sound improvements in fertilizer us... |
29. Managing Nitrogen to Optimize Yield and Quality of North Dakota Two-row Malting BarleyAs the demand of two-row malting barley (Hordeum vulgare L.) increases, having sound N recommendations is increasingly necessary. Not only does N play a role in grain yield, but it may also significantly impact grain malting characteristics including protein, plump, and test weight. To determine the impacts N rate and N availability have on two-row malting barley, two experimental sites were established in both Spring 2020 and 2021. The experiment was organized in a randomized comple... B. Goettl, H. Bu, A. Wick, D. Franzen |
30. Nitrate Soil Testing Correlation and Calibration Eastern Corn BeltCurrent economic and environmental concerns have increased the interest in developing methods to help manage nitrogen (N) fertilizers as efficiently as possible. There is a concern that fertilizer N that remains in the soil following harvest may be leaching below the root zone of crops and eventually ending up in groundwater. Agronomists throughout the corn belt are actively evaluating methods to manage N fertilizer as efficiently as possible.... |
31. Nitrate Testing ClinicsThirty-eight nitrate testing clinics were held in 36 Michigan counties in the spring of 1989. A mobile testing van was equipped for nitrate analysis of soil and water samples. Over 2,200 soil samples and 1500 water samples were analyzed for nitrate N using the nitrate ion-specific electrode. More than 50 percent of the soil samples . contained less than 30 lb of nitrate N in the surface two feet. Only 35 percent of the 1,100 fields were given a nitrogen credit based on the residual nitrate test.... |
32. Nitrogen Management for Cool Season Grass ProductionStudies were initiated in 1985 on established smooth bromegrass and tall fescue to evaluate urea granule size effects on forage production and quality. Other work, evaluating N source by previous source effects and UAN placement methods and the addition of ATS, was conducted on established smooth bromegrass. Nitroger1 rates were also evaluated in all these studies, and the addition of N significantly increased forage yields and N concentrations in each study. Use of large (1.0g) urea granules pr... |
33. Nitrogen Management for Winter Wheat in MissouriEight site years of data have been collected to evaluate nitrogen rate and timing for intensively managed winter wheat in Missouri. Variables have included rates up 160 lbs N per acre applied as all fall, all spring, or split in a fall and spring or fall plus two spring applications. Results have pointed to the split applications of rates at 80 to 120 lbs N per acre as providing greatest consistency and economic return to the grower. Maximum yield has generally been obtained with the 3 way split... |
34. Nitrogen Soil Test for Corn in OntarioIt is generally believed that for high yielding crops such as corn. the N requirements are much larger than variations in the N supplying capacity of soil. In Ontario, fertilizer N recommendations are based on the requirements of the crop and, for some crops, the expected yield goal. Nitrogen credits are given for past management such as manure application and legumes in rotation. The credits are deducted from the economic rate of N. In a recent analysis of all existing fertilizer N crop respon... |
35. Nitrogen Source Affects Manganese Nutrition of No Till CornA study evaluating response of no-till continuous corn to different rates of N as injected anhydrous ammonia and broadcasted urea-ammonium nitrate solution (UAN) was conducted on a Canfield silt loam near Wooster, Ohio. Repeated use of anhydrous ammonia on this naturally acid soil resulted in relatively large concentrations of Mn (often > 200 ug/g) in corn plant ear leaves at silking. Ear leaf Mn concentrations were less when UAN was used. For both N source treatments, ear leaf Mn concentrations... |
36. Nitrogen Test Development Soil N Levels in 1989The developnent of a N test that can be used for fertilizer recamrendations of corn in the eastern areas of Minnesota is needed for environmental and econcmic reasons. A multi-site project was initiated in 1989 to extensively examine soil sampling time and depth as well as N forms in the soil. This will then enable statistical models to be develaped using one or mre of the variables. A subset of the entire project is reported--concentrating on the sites allowing the calibration of the soil N tes... |
37. Nitrogen Timing Fertilization Strategies for Winter Wheat in WisconsinEconomically optimum winter wheat (Triticum aestivum L.) production relies on effective N application rate and timing. Previous research in Wisconsin indicates a need to better understand winter wheat response to N rate and application timing for growing conditions specific to the state. This study evaluated the effect of N application timing on yield, economic optimum N rate (EONR), agronomic N use efficiency (NUE), and profitability. A three-year study was conducted at three locati... J.D. Jones, C.A. Laboski, T.W. Andraski |
38. Phosphorous Management for Wheat ProductionProfitable wheat production depends on many factors, including a sound phosphorus (P) management program. Except for sunlight and water, soil fertility generally represents the most limiting factor in crop yields. Even with perfect weather and climatic conditions, a farmer that does everything right except to meet the nutrient needs of the crop will never reach optimum yield potential. Water, N, and P are generally the dominant yield limiting factors for wheat in the United States. Potassium, S,... |
39. Residual Soil NO3 N Variability Sampling Interpretation and Effect on Corn YieldResidual nitrate-N (NO3-N) in the soil profile (crop root zone) is seldom uniformly distributed. There is lateral as well as vertical variability. Numerous factors influence variability. Some of them are: 1) any factor that influences water movement through the soil such as - soil texture, compacted zone, topography and water distribution under irrigation - 2) previous crop, 3) fertilizer history (organic and inorganic sources) and 4) sampling time - caused primarily by factors influencing miner... |
40. Response of No-till Corn to Urease Inhibitors and Placement of N SourcesN(n-buty1)thiophosphoric triamide (NBPT) and ammonium thiosulfate (ATS) were investigated as urease inhibitors when added to urea and urea-containing N sources and applied to no- ill corn. Significant - f yield increases, some in excess of 20 bu ac , were observed with NBPT treatment of the N fertilizers. Lack of a yield response from NBPT, when it occurred, was usually associated with a rain event of major proportions soon after fertilizer application. ATS showed considerably less promise as a ... |
41. Seed Germination as Influenced by Fertilizer Type, Seed Coating, and Duration of StorageOverseeding forages into existing pastures and hayfields helps maintain dense stands and sustain productivity. Fertilizer applications to stimulate early spring growth provides an opportunity to blend forage seed with fertilizer. Additionally, seed treatments are often used to improve the ability to handle small seeds and to improve percent germination over raw or uncoated seed. Little is known about how seed coating, fertilizer type or duration of exposure to fertilizer will influence seed g... E. Ritchey, C. Teutsch |
42. Should Potassium Chloride be Applied to Soybean?Potassium chloride represents 98% of potassium sales in Minnesota. Potassium chloride contains 50% of chloride by mass. Research in the southern U.S. shows excess chloride is known to result in decreased soybean (Gylcine max var Merr.) yield. The objective of this study was to determine whether chloride impacts soybean yield in northern growing regions and evaluate the effect of rate (100 or 200 lb K ac-1) , fertilizer (K or Cl) source (none, KCl, K2SO4... D. Kaiser |
43. Site-Specific Yield and Protein Response to Nitrogen Rate and Timing in Winter WheatNitrogen (N) fertilizer management is crucial in cereal crop production. Improved prediction of optimal N fertilizer rates for winter wheat can decrease N losses and enhance profits. We tested seven N fertilizer rates (0, 25, 50, 75, 100, 125, and 150 kg N ha-1) applied at three timings (Fall, Spring, and Split Fall/Spring) in seven small plot trials located in commercial fields... J. Cesario Pereira Pinto, L. Puntel, L. Thompson, N. Mueller |
44. Soil and Soybean Responses to Planting into Terminated Prairie StripsPrairie strips are a new conservation practice that are currently implemented in 14 Midwest US states. Prairie strips have been shown to reduce runoff, increase soil health, retain sediment and nutrients, increase biodiversity and have no effect on surrounding crop yield. Due to the comprehensive improvements to soil health under prairie strips, researchers and growers are interested in rotating them on 10-15 year cycles. We have little-to-no knowledge on the effects of planting crops i... C. Dutter, M. St Cyr, M. Mcdaniel, C. Carley, A. Singh |
45. Soil Fertility Research in ManitobaA listing of current soil fertility research being conducted by the University or Manitoba, Agriculture and Agri-Food Canada (AAFC) and provincial extension (Manitoba Agriculture and Resource Development). Crops under study include corn, soybeans,, field peas, dry beans, spring wheat and canola. ... J. Heard |
46. Soil Health Indicators help with Fertilizer Application Decisions in South Dakota CornFertilizer inputs are an essential part of corn (Zea mays) cropping systems in the United States. In South Dakota, phosphorus and potassium yearly inputs are based on soil test nutrient levels and a yield goal while sulfur is based on soil texture and tillage practices. These 3 plant nutrients have a point called the “critical value” where addition of more of the nutrient as an inorganic fertilizer should no longer result in a yield increase. These fertilizer ... B. Groebner, J. Clark |
47. Soil Mineral Nitrogen Response to Nitrogen Fertilizer Application in Corn Early Growth SeasonSoil Mineral Nitrogen (SMN) plays a crucial role for the growth and productivity of crops such as corn, this crop is very demanding of nitrogen (N) in early growth stages. Maintaining the highest amount of N in the form of ammonium (NH4+) or nitrate (NO3-) can be key to obtaining high yields. Substances such as nitrification inhibitors (NI) were created to avoid losses of N from the soil. This study was carried out in 8 site year loca... P. Morinigo, D. Ruiz Diaz |
48. Some Thoughts on Nutrient Mineralization and Cycling in No-Till SystemsHigh post-harvest residue accumulations (10+ tons/acre) often occur in crop sequences involving high yielding corn, spring wheat and soybean. Over the last decade, we have conducted several studies that show that N or P availability may be suppressed either through slow residue decomposition, slow mineralization or immobilization. Although several states provide fertilizer recommendation adjustments for no-till and for high residue accumulations, the recommendations are sometimes contra... L. Cihacek, R. Alghamdi |
49. Soybean Growth and Yield Effects from Starter Fertilizer and Nitrogen ApplicationSpring Michigan weather variabilities and earlier planting dates may provide opportunities for starter fertilizer to affect soybean (Glycine max L) early season dry matter production while also decreasing the time interval for nutrient accumulation (i.e., lag-phase), but impacts on initiating biological N fixation (BNF) are not well known. Two trials were established near Lansing, MI to examine the effects of starter fertilizer and multiple nitrogen (N) application timings across two... K. Steinke, S. Soat |
50. Synergism Between Lime and Phosphate Fertilizer Application Enhances Soil Phosphorus AvailabilityBecause phosphorus (P) is a non-renewable resource and an essential mineral element for plant development, understanding factors that affect soil phosphorus bioavailability is crucial for sustainable food production. Soil organic P can account for a large fraction of the total soil P, and its mineralization can replenish the soil solution with plant-available P. Raising the soil pH with a liming agent can enhance soil biological activity and increase soil P availability in acidic soils, but i... M. Harm Loman, F.E. Below |
51. 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... |
52. The MRTN Approach: Past, Present, and FutureThe method of using crop N response data assimilation, now called the “MRTN approach”, was conceived at a September, 2004 meeting in Bettendorf, Iowa of scientists from several Corn Belt states. This meeting was prompted by findings in field trials that showed substantially lower optimum N rates than those based on using corn yield goal to predict crop N needs; most also showed no correlation between EONR and yield at EONR across trials. The MRTN method is straightforward: yield d... E. Nafziger, J. Sawyer |
53. The Nitrate Soil Test in South DakotaThe nitrate nitrogen soil test has been used for more than 15 years for making nitrogen fertilizer recommendations in South Dakota. Minimal leaching and denitrification due to a relatively dry climate has helped make this test a good predictor of nitrogen fertilizer needs. The test and nitrogen recommendation system is based on a two foot deep soil sample and a calibrated nitrogen requirement for common crops grown in South Dakota (Table 1). Extensive field plot data shows that the two foot deep... |
54. Winter Wheat Grain and Straw Impacts from Autumn Starter and Spring Nitrogen Fertilizer StrategiesThe overwintering success of winter wheat (Triticum aestivum L.) can be a determining yield factor in Michigan. Autumn-applied starter fertilizer may affect establishment, nutrient uptake, tiller production, and grain and straw yield. The objective of this study was to evaluate soft red winter wheat (SRWW) grain and straw yield in response to autumn applied starter fertilizer, spring nitrogen (N), and varietal stature. A two-year randomized complete block split-plot design w... K. Steinke, L. Thomas |