Proceedings
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1. Assessing the Variability of Corn Response to NitrogenBecause results of experiments designed to test the response of corn to N rate tend to vary considerably with the environment. repetitions of such studies over time are essential. It is not clear, however, what number of repetitions are needed in order to deduce sound recommendations for application of N fertilizer to succeeding crops. We used the results from 16 years of a crop rotation x N rate study conducted at Monmouth, Illinois to assess the effect of duration of such an experiment on the ... |
2. 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-s... |
3. Comprehensive Nutrient Management Plan from a USDA PerspectiveLivestock manure has emerged over the past few years as a major political, as well as an environmental issue. As the Congressional Research Service described the situation in a May 1998 report: "Social and political pressure to address the environmental impacts of livestock production has grown to the point that many policy-makers today are asking what to do, not whether to do something." It added: "The bulk of current policy debate on animal waste issues, both legislative and regulatory, is occ... |
4. Cover Crop Impacts on Corn and Soybean Nitrogen Accumulation and YieldThe need to retain soil N between economic crops has renewed interest in cover crops for the eastern cornbelt but their management remains a barrier to widespread adoption. We conducted a 3 site-yr study to determine effects of cover species (wheat or rye) and biomass management (burndown 40 d, 20 d, or 2 d preplant) on corn and soybean yields. Sites included a very poorly drained (wland wlo tile drainage) and a well drained silt loam. With adequate drainage, cover biomass 40 d preplant averaged... |
5. Early Season Stresses in CornSpatial variability in corn yield is frequently associated with lost yield potential caused by plant stresses. Early-season stresses are difficult to recognize because growing conditions (soil temperature and water status) are not ideal and seldom uniform throughout a field. The impact that climate has on plant growth is dificult to determine because it also affects nitrogen (N) availability. Nitrogen stress was imposed sequentially until the V8 growth stage and then all plots were sidedressed w... |
6. Effect of Time of N Application for CornThe economic benefit associated with the application of N fertilizers for corn has been known for over 5 decades. As a result, over 99 % of the farmers in Illinois apply N fertilizers when corn is grown. Unlike phosphorus and potassium, there is no good soil test to predict the amount of N needed, instead, farmers use a factor times yield potential with appropriate credits for legume and other N sources to set N rates. While this works well over a number of years, there are years when less N wil... |
7. Effects of Phosphorus Application Method and Rate on Furrow-irrigated Ridge-tilled Grain SorghumThe objective of this research was to investigate the effects of method of phosphorus (P) placement and rate on inigated grain sorghum grown in a ridge-tillage system on a soil low in available P. This experiment was conducted from 1993-1 995 on a producer's field near the North Central Kansas Experiment Field Experiment Field at Scandia, Kansas on a Carr sandy loam soil. Treatments consisted of fertilizer application methods: surface broadcast, single band starter (2 inches to the side and 2 in... |
8. Evaluation of Nitrogen Management Practices in No-till Corn ProductionExperiments were conducted fiom 1995 to 1998 at the Dixon Springs Agricultural Center of the University of Illinois and the Belleville Research Center of Southern Illinois University to evaluate agronomically and economically several nitrogen (N) management options, including the use of the urease inhibitor Agrotaii, in no-till corn production. Compared in these studies were N sources (urea, UAN, ammonium nitrate, and anhydrous ammonia), placement (dribble vs. broadcast for surface-applied N and... |
9. Nitrate Concentrations in Drainage Water from a Continuous Corn Production System- Impacts of Tile Spacing and Precipitation EventsCharacterization of agricultural drains as point sources for nitrates in surface waters has generated keen interest in regional grab-sample monitoring programs. Grab sample tile drain monitoring programs are being explored by numerous public and private organizations interested in encouraging BMPYs for nitrogen and/or implementation of TMDL policy. Our objective was to determine if nitrate concentrations in water collected from individual tile lines could be interpreted independent of informatio... |
10. 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 sit... |
11. Optimal Phosphorus Response in Site-specific FarmingSite-specific farming has provided an opportunity to collect large amounts of field data, but traditional agronomic yield response models have not been developed to exploit this mformation. This research presents a yield model that incorporates detailed site-specific field information (e.g., soil pH. soil test P, K, and N, fertilizer rates), providing improved fertilizer decision making. A quadratic yield response function and a modified asymptotic Mitscherlich function are compared for irrigate... |
12. Phosphate Management for the Corn Soybean RotationThe evaluation of rate, Frequency, and placement of phosphorus (P) fertilizer on production in the codsoybean rotation was evaluated for two contrasting tillage systems. A primary objective of this study was to evaluate both yield and economic response for the full crop rotation. Tillage systems compared were fall chisel plow and no-till. Application rates ranged from 0 to 92 Ibs P205 ac-' yr-l and were fall applied either annually or at double the rate on a biennial basis. The biennial applicat... |
13. Potassium Placement in Conservation Tillage- cropping System ConsiderationsSoil fertility specialists have repeatedly observed that significant stratification of both P and K occurs on fields which are kept in no-till production, even if that time period is as short as three years. The actual degree of K stratification is affected by soil texture, the method of fertilizer application, crop rotation history, precipitation levels and surface residue management. Potassium stratification isn't inherently deleterious to crop production in a given environment. Crop yield los... |
14. Relationship of Seed-placed Phosphatic Fertilizer Salt Index to Crop EmergenceThe role of fertilizer salt index in salt injury to germinating seeds has been recognized for over 60 years. Recent increased use of direct seed placement of fertilizer P has produced a need for a simpler method of making seed-placed fertilizer recommendations. Numerous field studies were conducted utilizing seed-placed P fertilizers. Published fertilizer salt index values were multiplied by the PtOs/ha application rate to give a salt indexha value. Relative plant stand (dependent variable) was ... |
15. 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 ... |
16. Site Specific Nitrogen and Irrigation Management Across Nebraska Agro-ecological ZonesNitrogen leaching below hrrow irrigated ground has caused nitrate contamination in Nebraska's groundwater. Alternate row irrigation and alternate row nitrogen fertilization is proposed as a method to decrease water use and decrease nitrogen leaching. Nitrogen was applied at a uniform and variable rates based on spring grid sampling for nitrate and soil organic matter. The experiment was conducted at three sites in Nebraska that represent a range of growing conditions. At these sites the average ... |
17. Soil Fertility for Functional FoodsIn the agri-food industry today, two trends cannot be ignored. First, the health conscious "baby boom" generation is demanding and will continue to demand foods that enhance their wellness. Crop producers must increasingly focus on the goal of producing crops that meet their needs. Second, the tools of molecular biology give agricultural scientists the opportunity to attain that goal. Biotechnology involves not only genetic engineering, but also includes tools that enhance the traditional select... |
18. Soil Fertility Trends in a Long Term Crop Rotataion-Soil Fertility TrialPenn State soil test recommendations are based on fertilizing for crop response at soil test levels below the critical level for response, maintenance fertilization based on expected crop removal in the optimum range just above the critical level, and finally no fertilizer recommended in the high range. Using a sufficiency level approach, a soil that was at the critical level would have a zero recommendation, however this zero recommendation would not be valid for 3 or 4 years until a new soil t... |
19. Soil Phosphorus Chemistry- Agronomic and Environmental ApplicationsPhosphorus (P) has been a heavily researched topic in soil science for many years. For example, a search of the AGMCOLA database from 1970 to present turned up nearly 6000 citations under the key words soil and phosphorus. The fact that P is essential to all forms of life has promoted these research activities. as one would expect. In addition, the complexity of the soil P cycle has yet to be fully understood and appreciated by the scientific community. Further, while early research focused on c... |
20. Soybean Chlorosis in North Dakota- Causes, Severity and Possible SolutionsSoybean acres continue to increase in northwestern Minnesota and North Dakota in spite of severe problems with iron chlorosis in some years. Soybeans often turn yellow within a few weeks of emergence and remain yellow for up to 8 weeks before plants green up and mature. Iron chlorosis tolerant soybeans available today are somewhat effective in reducing chlorotic acreage, but are not tolerant enough to counteract the soil conditions in this area. Several researchers have found that iron chlorosis... |
21. Subsoiling No-tillage CornCurrently, over half of the corn in Kentucky is no-till planted. Many fields have received little tillage in the last 10 to 20 years. Many producers wonder if soil compaction increases with time on these long term no-till fields due to annual trafficking with heavy equipment. Subsoiling implements are available that allow subsurface tillage while preserving the surface mulch layer. This allows for continued no-till planting while introducing some tillage into the cropping system. Some producers ... |
22. Yield of Sugar Beet, Soybean,Corn, Field Bean and Wheat as affected by Lime Applications on High Soil pHLime from sugar beet processing plants has been stockpiled for 100 years. Environmental regulations and limited storage space provide an impetus for the removal of the material. Land application on alkaline soils is one alternative for disposal of this material. This study was undertaken to evaluate the effect of applying sugar beet processing lime on crop production on these soils. Studies were conducted at seven sites representing four alkaline soil series in Michigan. Lime was applied at rate... |