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1. 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 |
2. 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... |
3. Relationship Between Soil P and P in Surface Runoff and Subsurface Drainage- An Overview of Ongoing ResearchNonpoint source pollution fiom agricultural fields has the potential to accelerate eutrophication of fieshwater ecosystems. In a report of water quality in the United States, the Environmental Protection Agency sited agriculture as the primary source of pollution in 60% of impaired river miles, 30% of the impaired lake acres and 15% of estuarine square miles @PA, 1998). Phosphorus, in particular, has received much attention due to its role as limiting nutrient in many fieshwater ecosystems (Correll,... |
4. Soil Phosphorus Spatial Distribution in Pastures Receiving Poultry Litter ApplicationsEnvironmentally-based P management strategies could be improved by debeating management zones incorporating the effects of landscape position on soil morphology, hydrology, and soil P distribution. Three farm pasture sites in SW Missouri receiving long-term poultry litter applications were sampled by landscape position (summit, shoulder, upper backslope. middle backslope, lower backslope, footslope, drain) for soil P (Bray 1 P, CaCl2 P, total P) at two depths (0-5 cm, 5- 15 cm). Low landscape positions... |
5. 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... |
6. Should We Abandon Soil Testing and Yield Goals in Estimating Nitrogen Rates for CornIf the prices of corn and fertilizer-N and the shape of the N response function relating crop yield to the amount of fertilizer used are known, calculating an economically optimal N rate (EONR) for maximizing the net return to applied N is straightforward: the EONR is the N rate at which no firher increase in net return occurs. In most cropping systems and under common price scenarios, crop yield at the EONR is within 95 to 99% of the maximum yield obtained for the specific management package. In... |
7. Swine Manure Applications for Soybean Production - Environnmental and Pathological ImplicationsSoybeans are leguminous plant sp ecies capable of fixing nitrogen (N) from the atmosphere to support their growth and development. Despite th e fact that soybeans can fix their own N, in a soil environment rich in inorgani c N they will scavenge for available N decreasing the level of root nodulation (Schmidt et al., 2000; Hester man and Isleib, 1991). Studies conducted to measure the impact of N fertilization of soybean s reveals that crop response to commercial N fertilizer does not result in increased... |
8. Management Zone Delineation Techniques to Aid In-Season Sensor Based Nitrogen ApplicationThe increased efficiency of nitr ogen fertilizer (N) use has been a long-term goal in reduction of nitrate contamination in the stat e of Nebraska. Preliminary rese arch has shown sensor based in- season application of nitrogen has the ability to be economic and environmentally viable. Although benefits have been published there is an opportunity for increased accuracy of N application through the integration of preprocesse d georeferenced management zones. In-season sensor based N application relies... |
9. Slow-Release Fertilizer Effect on Groundwater Nitrogen Concentration in Sandy Soils under Potato ProductionCurrent nitrogen (N) fertilizer management practices for potato farming have led to elevated levels of N in the local groundwater. Slow-release fertilizer, specifically Environmentally Smart Nitrogen® (ESN®) polymer coated urea (PCU ) may reduce the amount of N leaching to groundwater; however no field scale studies have been performed in Wisconsin to validate these assertions. Field experiments were conducted at the Hancock Agricultural Research Station using Russet Burbank potato, planted in... |
10. Managing Riparian Buffers to Improve Soil Structural PropertiesFifty-five percent of Kentucky's stream impairments have been attributed to agriculture. Riparian buffer management may improve buffer effectiveness and reduce agricultural contaminants impairing water quality. Three mowing regimes and one native grass establishment regime were imposed in the riparian buffer zone surrounding a tributary of Cane Run Creek in Fayette County KY. Treatment plots measured 10m x 15m, with 10 replications of each treatment. One year after treatment, root biomass, soil aggregate... |
11. Soybean Production Research: A National ApproachU.S. soybean growers are looking for alternative methods to increase soybean yields and recent increases in commodity prices have given producers more freedom to invest in additional crop inputs or products. Unfortunately, quality data from studies addressing multiple contemporary inputs is scarce. The objective of this work was to evaluate the effectiveness of combined soybean inputs on seed yield. These high input systems were tested in six states to evaluate their value across a broad geography.... |
12. Overview of Manure Handling on Steroid Movement in Agricultural Fields from Beef Cattle SystemsManure generated from concentrated animal feeding operations may serve as a source of steroids in surface water and potentially in groundwater. The objectives of this research were to determine the amount of steroids and metabolites in runoff from beef cattle production pens, and from runoff and leaching from crop production fields. Cattle were fed a synthetic progestagen, MGA or melengestrol acetate and treated with zeranol, trenbolone acetate, and estradiol implants, while a second group was not... |
13. 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 |
14. 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 |
15. Manure Total Nitrogen Variability Due to Analytical Method and Total Solids ContentKnowing the nutrient analysis of a fertilizer source is essential to ensure adequate nutrients for crop growth, while not causing potential environmental impacts by overapplying nutrients. Using manure as a nutrient source can complicate matters as the nutrient content can be variable and the manure can come in a range of liquid to solid consistencies. There are multiple laboratory methods to determine different nutrient parameters and for manure total nitrogen levels the most common methods... N.L. Bohl Bormann, M.L. Wilson, E.L. Cortus, J. Floren, R.O. Miller, L. Gunderson |
16. US Midwest Dairy Manure Nutrient Observations 2012-2022Dairy manure is a source of organic nutrients with variable manure characteristics. This analysis drew 2012-2022 data from ManureDB, the manure and organic amendment database developed by the University of Minnesota. Thousands of solid dairy and liquid dairy manure samples across 2012-2022 were evaluated for book value comparisons, temporal trends, and regional differences for total N, NH4-N, P2O5, and K2O analytes. The only significant trend detected... N. Bohl Bormann, M. Wilson, E.L. Cortus, K.A. Silverstein, K.A. Janni, L. Gunderson |