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1. High Yield Corn ResearchThe objective of this study was to evaluate four corn hybrids at 15 and 30 inch row spacing and at plant densities of 28,000 and 34,000 plants per acre. The irrigated study was conducted at East Lansing on a Metea loamy sand soil. The 15 inch row spacing was obtained by back-planting in between 30 inch rows. Other cultural and management inputs are described at the bottom of Table 1. The first obviously noticeable difference in 1984 was the uneven stand in the 15 inch row spacing particularly for... |
2. 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... |
3. Evaluation of Soil Profile NO3-N for Prediction of N Fertilizer RequirementsCurrent N recommendation systems based on yield goal with adjustment for previous legume crop or manure applications have worked well in many situations. In the example given in Table 1, multiplying the 8 year average yield times 1.2 lb N/bushel would result in a recommendation within 20 Ibs N/acre of the optimum in 6 of the 8 years. As expected, this system resulted in significant over recommendation in the 1988 and 1989 drought years. While these results provide confidence that the system works... |
4. Evaluation of Three N Recommendation Systems for Corn Yield and Residual Soil NitrateProper N application rates are required for continued economic and environmental viability of U.S. agriculture. Application at rates below that required for economic optimum will place U.S. farmers at a competitive disadvantage in the world market. On the other hand, excessive rates of N fertilizers may result in contamination of ground water. ... |
5. On-The-Go Sensors for variable rate Nutrient Management- Determining Soil K Status with a Flat-Surface Ion-Selective ElectrodeTraditional soil sampling approaches are frequently not sufficiently spatially dense to characterize within field variability in soil fertiiity. Recent technology advances have demonstrated the feasibility of using automated soil sampling systems and tractor mounted sensors to create nutrient availability maps from more continuous measurements. Our objective was to determine if a flat-surface ion selective K electrode could measure soil K status at field moisture content. Twenty-four agricultural... |
6. Response of Corn to N Fertilization in Fall, Spring, and (or) SummerPrecision farming technologies (remote sensing of canopy reflectance and yield monitoring) were used to study the response of corn after soybean to fertilizer N applied at different times in three field-scale trials in central Iowa in 1999. Weather conditions were unusually favorable for losses of fall-applied N and crop responses to N indicated that substantial losses occurred. Yields of corn could be maintained by adding a nitrification inhibitor or additional N, but the greatest profit was attained... |
7. Soil Electrical Conductivity Map Quality- Impact of Interpolation Search Neighborhood ParametersSpatial predictions of soil electrical conductivity (EC) measurements may be improved by adjusting the search neighborhood criteria. The objective of this study was to investigate how varying search parameters impacted the quality of soil EC maps. The three fields cl~osen for this study were from the Inner and Outer Blue Grass physiographic regions of Kentucky. Soil EC was measured by direct contact at all locations. The prediction datasets included EC measurements along transects that were separated... |
8. A Novel Use of Data Translation Allows 3D Prediction of Soil Fertility LandscapesSoil fertility managers need better estimates of the subsoil contribution to the nutrient pool. Thls need could be achieved through 3-D predictions of subsoil fertility using a novel method of soil- profile data translation in relation to a controlling genetic horizon. For this translation, the depth of a controlling pedogenic feature is used as the origin and the rest of the profile is linearly scaled to it. When applied to a group of soils, from across a local or regional landscape, with varying... |
9. Effect of Timing of Broadcast Potassium (K) on Soybean Yield and Seed K ContentIn Indiana, the common practice is for K fertilizer to be applied in advance of the corn crop for both crops in the rotation, relegating soybean to feed on the application residual. Producers are concerned that current University guidelines and common practices for K management in corn- soybean rotations do not fully recognize the particular K needs of the soybean crop as differentiated from the corn crop. A four-location, six-year field study was conducted to investigate the effects of rate and... |
10. Zone Delineation for Nitrogen ManagementManaging nitrogen through zone soil sampling has been shown effective in revealing residual soil nitrate patterns in North Dakota. Zone delineation has been constructed using several types of data, including yield maps, remote imagery, topography and soil EC sensor data. A study was conducted in North Dakota, Montana and Minnesota to evaluate zone delineation methods. Across the region, yield frequency maps, topography, remote inlagery and soil EC data were effective in helping to construct zones.... |
11. Assessment of the Combined Effects of Soil pH and Carbonates on Soybean Yield and Development of Iron Deficiency ChlorosisSoybean is extensively grown in areas of the Midwest where fields often have areas of acid to calcareous soils intermingled in complex spatial patterns. Soil pH is highly buffered by carbonates, and measured pH usually ranges from 7.5 to 8.3 depending on the concentration of C02 and other factors. Soybean grown on high-pH calcareous soils often shows iron (Fe) deficiency chlorosis (IDC). Symptoms of IDC include yellowing of interveinal areas of young leaves and, as the deficiency becomes severe,... |
12. Uptake and Leaching Potential Of Potassium And Sulfur When Split Applied For Corn on Irrigated SoilCoarse textured soils used in irrigated agriculture often face nutrient losses through the soil profile due to low cation exchange capacity (CEC). Split fertilizer application on sandy soils has been recommended for the corn crops in MN to avoid the leaching of fertilizers nutrients. Our study aimed to look at the potential for potassium and sulfur to be taken up or leached out in corn production. Two K and two S fertilizers studies were set up in Minnesota on coarse irrigated soils. Each site had... |
13. Roto and Shoot Biomass and Nutrient Composition in a Winter Rye Cover CropNitrogen loss from applied fertilizer can be a significant environmental quality issue if NO 3 moves to surface or ground water. The Iowa nutrient reduction strategy science assessment identified winter cereal rye (Secale cereal L.) cover crop as a practice that can significantly reduce N and P loss (41% NO 3-N and 21% P reduction) from corn (Zea mays L.) and soybean [Glycine max. (L.) Merr.] fields. Cereal rye, when used as a cover crop, through its fibrous root system is able to explore the soil... |
14. Which Corn Nitrogen Fertilization Rate Tools Preforms the Best in the Midwest?Publicly-available nitrogen (N) rate recommendation tools are utilized to help maximize yield in corn production. These tools often fail when N is over-applied and results in excess N being lost to the environment, or when N is under-applied and results in decreased yield and economic returns. Performance of a tool is often based on the specific soil and weather conditions of a growing season. Research is needed to determine which tools are the most effective at recommending economical optimal N... |
15. Biochar: Waste, or Product?Nutrient losses following summer and fall manure applications result in economic and water quality problems. We tested the potential of biochar (BC) and ammonium thiosulphate (ATS) as manure additives to retain nutrients by reduci ng nitrate pool size and runoff of N and P. To determine appropriate rates to use in field expe riments, the compounds were initially added at different rates to liquid swine manure (LSM) then the slurry mixed with soil and incubated. The selected rates, based on N transformations,... |
16. Evaluation of Sulfur Fertilizers In Corn ProductionSulfur deficiencies and corn yield increases from S fertilization have been documented in Iowa since the mid-2000’s. Therefore, S fertilization management is an important component of high yield corn production. Many S fertilizers are available for use in correcting deficiencies. However, specific product evaluations have not been widely conducted in Iowa. In addition, a new S fertilizer has recently become available in the Midwest U.S., the mineral polyhalite. The research objectives were... J. Sawyer, M. Castellano, A. Sassman, J. Lundvall |
17. Winter Cereal Rye Nitrogen Response and Fertilization RequirementWinter cereal rye (Secale cereale L.) has been a common cover crop choice due to seed cost, winter hardiness, and rapid spring growth. It could also be an alternative grain crop to include in a corn-soybean rotation. Also, a rye crop would provide soil coverage during the springtime when corn and soybean do not. No known research has investigated the N fertilization requirement for winter cereal rye seed production in Iowa. The objectives of this study were to evaluate N response in cereal... C. Martins, J. Sawyer, J. Lundvall |
18. Assessment of Plant Nitrogen Uptake with Late Fertilizer Applications in CornPrevious research in Kansas and other regions has shown that split applications of N fertilizer with early side-dress can increase yield compared to applications at planting in some site years. Split applications are typically done using the traditional side dress at the V6-V8 growth stage. However, late N applications (late-vegetative or early reproductive stage) is generating interest as one alternative to improve nitrogen use efficiency and possibly increase yields,... D. Diaz, A. Stammer, F. Hansel |
19. 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 |
20. Active-Optical Reflectance Sensing Evaluated for Red and Red-Edge Waveband SensitivityUncertainty exists with corn (Zea mays L.) N management due to year-to-year variation in crop N need, soil N supply, and N loss from leaching, volatilization, and denitrification. Active-optical reflectance sensing (AORS) has proven effective in some fields for generating N fertilizer recommendations that improve N use efficiency. However, various sensors utilize different wavebands of light to calculate N fertilizer recommendations making it difficult to know which waveband is most sensitive... G. Bean, N. Kitchen, J. Camberato, R. Ferguson, F. Fernandez, D. Franzen, C. Laboski, E. Nafziger, J. Sawyer, P. Scharf, J. Schepers, J. Shanahan |
21. Do Split-Nitrogen Applications in the Midwest Affect Corn Nitrogen Uptake and Grain Yield?It is hypothesized that split-nitrogen (N) relative to single near-planting applications improve corn (Zea mays L.) grain yield and nitrogen recovery efficiency, which can lessen environmental impacts of fertilization. However, these hypotheses have not been fully tested. A 49-site-year study across eight US Midwestern states over three years was conducted to compare near-planting (Single) and split-N (Split) applications. Three N application timings were evaluated [Single near planting, 40... J. Clark, F. Fernandez, J. Camberato, P. Carter, R. Ferguson, D. Franzen, N. Kitchen, C. Laboski, E. Nafziger, J. Sawyer, J. Shanahan |
22. 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 |
23. The Anaerobic Potentially Mineralizable Nitrogen Test as a Tool for Nitrogen Management in the MidwestThe anaerobic potentially mineralizable nitrogen (PMNan) test is a tool that can improve estimations of mineralizable nitrogen (N) and enhance nitrogen use efficiency. This tool may also help improve predictions of N uptake, grain yield, and the economic optimum nitrogen rate (EONR) of corn (Zea mays L.). A 32 site-year study across eight US Midwestern states was conducted to 1) compare the effect of incubation length (7-, 14-, 28-d), soil sampling timing, N fertilizer rate, and their... J. Clark, K. Sloan veum, F. Fernandez, J. Camberato, P. Carter, R. Ferguson, D. Franzen, N. Kitchen, C. Laboski, E. Nafziger, J. Sawyer, J. Shanahan |
24. Impact of Nitrogen Application Timing on Corn ProductionWater quality issues have renewed interest in timing of nitrogen (N) application as a means to improve use efficiency in corn and reduce losses. Improved economic return is also desired as N fertilization is one of the most costly inputs to corn production. Time of fertilizer application is a component of the site-specific 4R nutrient management stewardship programs. In Iowa, the Nutrient Reduction Strategy has a 7% (37% std. dev.) nitrate-N reduction with a 0% (3% std. dev.) corn yield change... J. Sawyer, D. Barker, J. Lundvall |
25. 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 data... E. Nafziger, J. Sawyer |
26. Cover Crop Species and Planting Methods Influence on Corn N Requirement in Southern IllinoisIt is well established that planting cover crops prior to corn (Zea mays L.) can influence soil temperature, moisture, and nitrogen (N) dynamics. These changes in soil along with the effects of cover crop on corn plant population can influence corn grain yield and N requirement. Two strategies to facilitate corn establishment and avoid N immobilization especially in winter cereal cover crops is by mixing cover crop species or skipping the corn row (precision planting). A randomized complete... A. Sadeghpour, C. Kula, G. Sener, C. Vick |
27. Response of Corn to Planting Methods of Cover Crop Species and Nitrogen Rate in Southern IllinoisIt is well established that planting cover crops prior to corn (Zea mays L.) can influence soil temperature, moisture, and nitrogen (N) dynamics. These changes in soil along with the effects of cover crop on corn plant population can influence corn grain yield and N requirement. Two strategies to facilitate corn establishment and avoid N immobilization especially in winter cereal cover crops is by mixing cover crop species or skipping the corn row (precision planting). A randomized complete... A. Sadeghpour, G. Sener guzel, C. Kula, C. Vick |