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1. 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... |
2. Ammonia Band Spacing Effects on Ammonium Persistence in the BandResults from four field experiments (1991 and 1992) showed that anhydrous ammonia (AA) concentration in the band increased NH4-N persistence in the Hord and Sharpsburg soils in 1992, but not in the Cass and Zook soils in 1991. In 1992, average half-life across both soils was increased from 14 days when applied in a 38 cm spacing to 66 days when applied in a 152 cm spacing (every other row) at the high application rate (224 kg N ha-'). A half-life of 66 days indicates 25% of the applied AA would ... |
3. 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... |
4. Crop Residue and Fertilizer Management Effects on Soybean, Wheat, and Grain Sorghum in Eastern KansasRemoval of crop residue is being considered for many non- agricultural uses. The agronomic consequences of these practices are not fully known, especially for different levels of fertilizer management. An experiment was begun in eastern Kansas in 1980 to determine the effects of returning different levels of crop residue on soil properties and crop yields in a soybean-wheat-grain sorghum rotation, fertilized with different amounts of N-P-K fertilizer. Crop residue treatments included residue rem... |
5. 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... |
6. 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 ... |
7. Effect of NBPT-Amended Urea and UAN on No-till Corn in Northern IllinoisField evaluations of the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) have been extensively conducted across the USA with encouraging results. Most response data collected to date has been with corn. In this report results from 7 'years of experiments at two southern Illinois locations (Belleville and Carbondale) are presented. NBPT addition to broadcast-placed urea, when evaluated across N rates and locations, gave no- till corn yield increases averaging 8.4 bulac in 13 experimen... |
8. Effects of Residue Management on Fertilizer use Efficiency on Corn in the Western Corn BeltInterest in residue management began in parts of the Great Plains following the "dirty thirties" when the government responded to wind and water erosion problems by creating the Soil Conservation Service. Stubble mulch in winter wheat production areas evolved into no-till as herbicides becan~e available. Interest in limited or no till systems in the Corn Belt began in the 1950's. Higher residue levels are required to reduce erosion while maintaining soil productivity but an additional reason is ... |
9. 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... |
10. Field Scale Fertilizer Recommendations and Spatial VariabilityFertilizer is usually applied at a single constant rate across a field. However, soil fertility may vary considerably within a field. Soil test calibrations (ie recommended fertilizer versus soil test ) are usually obtained from sites with low spatial variability of soil test values (ex. small plots ). These calibrations are then assumed to be valid for large fields with variable soil fertility. The effects of variable soil fertility on the relationship between average crop yield response, avera... |
11. Hybrid and Potash Effects on Root Growth in Ridge-till CornPotassium deficiency symptoms often appear in ridge-till and no-till corn even when soil test values for potassium are high. Certain hybrids are morc sensitive to the problem than others. Two techniques were used to assess root activity arid density in a three year experiment at the West Central Experiment Station, Morris, MN. We compared two tillage systems (fall chisel and ridge till). two hybrids (Pioneer 3732 and 3737) and three fertilizer treatments (control and 40 IbIA banded or broadcast ... |
12. Impact of Excess Water on N LossThe impact of excess soil water on N use efficiency by corn was evaluated over several years at four locations in Illinois. At each location, 0, 4, or 6 inches of water was applied in late May to soils that were at field capacity. Prior to the addition of the excess water, potassium nitrate was applied at rates ranging from 0 to 200 Ib Nlacre. On medium to heavy textured soils, the number of days when soil moisture was at saturation provided a good estimate of the magnitude of N loss. Yields we... |
13. Influence of Water Treatment Lime Sludge on Soil pH and Crop YieldsSoil pH levels are decreasing in extreme Eastern South Dakota. To test the effectiveness of water treatment lime sludge in raising soil pH and crop yields, a liming study was established at four locations with pH levels of 5.7 or less. The lime sludge applied at 3 tons per acre raised soil pH to neutral and maintained it at neutral for the 4 year duration of the study. Crops grown at the various sites included soybeans, corn, spring wheat, winter wheat and forage sorghum. Although there was a t... |
14. 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 ... |
15. 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... |
16. Manure Brokerage in OhioIn Ohio there are several counties where annual manure production exceeds the requirements of all crops grown in the county. Poor distribution of this manure has created instances where soils have become overloaded with phosphorus, contributing to the phosphorus load of surface waters and creating the potential for long term release of phosphorus into states waters. Nitrogen also becomes an environmental concern as excess nutrient loads are placed on soils, nitrogen is found leaching through til... |
17. Michigan Right-to-Farm- Generally Accepted Agricultural and Management Practices for Nutrient UtilizationThe following is a summary of Michigan's Right-To-Farm nutrient management practices. These practices were adopted by the Michigan Agricultural Con~mission in January of 1993. Crop producers who voluntarily follow these practices are provided protection from public nuisance disputes under Michigan Public Act 93 of 1981 as amended, The Right-To-Farm Act, Michigan Department of Agriculture. A complete copy of the Right-To-Farm document may be obtained by writing to Robert Craig. Michigan Departmen... |
18. 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.... |
19. 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.... |
20. Nitrogen and Water ManagementIt is difficult to separate N and water management when developing improved management systems for irrigated corn production. This is because adequate supplies of both N and water are critical for crop growth, but excesses of either or both can threaten ground water quality. Several N and water management systems were established at the Nebraska Management Systems Evaluation Area (MSEA) project to evaluate the impact of improved irrigation and N fertilizer management practices on production and... |
21. 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... |
22. Nitrogen Management for Profitability and Groundwater ProtectionSugarbeet production practices have changed drastically in the last two decades in Minnesota and North Dakota. Changes in grower payment systems mandated change to production of high sugar content low impurity level beets. Development, refinement and extensive use of the soil nitrate-N test in concert with the sugar company quality payment program resulted in greatly reduced N fertilizer use while increasing crop yield and quality.... |
23. 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... |
24. 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... |
25. 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... |
26. 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... |
27. Pass--An Improved System for Combining Dris and Sufficiency Range Approaches to Plant AnalysisThe University of Wisconsin Soil & Plant Analysis Lab (UW-Lab) includes both the Sufficiency Range (SR) and the Diagnosis and Recommendations Lntegrated System (DRIS) interpretations in plant analysis reports. The UW-Lab added the DRIS to its routine plant analysis program in 1992. Soon after its introduction, the DRIS appeared to be diagnosing Ca as yield-limiting in many cases where the SR interpreted Ca as sufficient. The DRIS diagnosis of Ca as deficient also contradicted previous research w... |
28. 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,... |
29. Regionalizing Fertilizer Recommendations for North Dakota, South Dakota, and Western MinnesotaFertilizer recommendations have varied between adjacent states. The inconsistencies at state lines made educational efforts in soil fertility more difficult for companies doing business across state lines. In an effort to alleviate these problems, the agronomists working with fertilizer calibration data and recommendations from the three states of North Dakota, South Dakota and Minnesota put together a recommendation system which could be used in a large part of all three states. The basic "core... |
30. Regionalizing Nutrient Recommendations Indiana- Ohio- MichiganWHY THE INTEREST IN REGIONALIZE CROP NUTRIENT RECOMMENDATIONS ? 1) Wide variations in recommendations made to farmers by who makes them. a) by fertilizer dealers or sellers of product b) by llunbiasu consultants c) by soil testing labs d) by Universities e) by other governmental agencies 2) Philosophies are different in "What is best for Mr. Farmeru a) Sufficiency Level of Fertilization - "Feed the Cropw b) Build-up & Maintenance - "Feed the Soilt1 c) Cation Balance Method - "Keep everything in ... |
31. 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... |
32. Residue Management Systems in the Northern Corn Beltn the northern corn belt (Michigan, Wisconsin, and Minnesota) it is very important to minimize negative effects of crop residue (stand establishment and phenology). Soil cover in the row by crop residue (corn, small grain, or soybean residues) should be less than 10% in a strip 6 to 8 inches wide for corn. Mineralization of organic N sources such as legume residues, soil organic matter, and manure is reduced with systems that eliminate full width deep tillage such as ridge till, no till, or shal... |
33. 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 ... |
34. Selected Soil Chemical Properties and Corn Grain Yield Under Different Manure SystemsThe Iowa Department of Agriculture and Land Stewardship estimated 1987 farm animal populations to be 4.6 million cattle and calves and 13.8 million hogs and pigs (26% of the nation's hogs). The animals produced about 141,987 tons of plant available N if 50% of the excreted N is available the first year of application. This amounts to 22 lb of N for every corn acre in Iowa. Most of the livestock operations are intensive with high populations of animals on a sniall land area. Nutrients in feed are... |
35. Survey of Corn Response to Fertilizer Sulfur in MissouriAbstract Fertilizer sulfur (S) rate studies were conducted during 1991 and 1992 at 53 sites located throughout Missouri on soils that were primarily silt loam or heavier. Sites were selected on the basis of a high yield potential since a common belief among farmers and fertilizer dealers is that the greater crop S requirement of high yields exceeds the S supply from the soil and incidental sources. Either ammonium sulfate or ammonium thosulfate were applied at planting or wihn four weeks followi... |
36. 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... |
37. 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... |
38. The State of the Art StartersInterest in reduced tillage has caused a resurgence in the use of starter fertilizer. Starter fertilizer research has been conducted on many crops across the country. The purpose of this paper is to highlight recent research on a variety of crops including corn. cotton, sorghum, soybean, canola, sugar beet, and potato. Increased yields from starter fertilizers are common in low P soils and several factors may lead to increased yields even when soil P and K levels are high. Geographic trends in y... |
39. Update on the Certified Crop Adviser-CCA-ProgramThe Certified Crop Adviser (CCA) program implemented by the American Society of Agronomy (ASA) and the American Registry for Certified Professionals in Agronomy, Crops; and Soils (ARCPACS) through the cooperation of various state and regional boards will soon begin its second year. To date approximately 2100 people have taken the state and/or national exams and are in the process of completing the other requirements for certification. Several new state or multi-state CCA Boards have been organiz... |
40. 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 c... |
41. Variable-Rate Fertilizer Application- Update and EconomicsThe potential for application of computer-controlled, satellite-guided, variable-rate application systems for fertilizer has opened an interesting new area of research and development. While variable-rate application is not new--and does not require the com- puter or satellite systems to be useful--the technology is definitely helping to convince dealers and farmers that this concept has broader potential. Economic pressures and environmental concerns are leading them to take a closer look at ho... |