Proceedings
Authors
| Filter results12 paper(s) found. |
|---|
1. 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... |
2. Vegetative Assessment of Phosphorus and Nitrogen Status in Maize Using Remote SensingAssess spatial variability of soil P and N is not only costly but also a time consuming processes. Remote sensing measurements of canopy spectral reflectance can provide a rapid and non- destructive method for assessing plant-canopy nutrient status. The main objective of this research was to detect P and N stress during the early corn growth by selecting specific wavelengths, or combinations of them, using narrow band field sensors. In 2001, two corn experiments were planted over an old manure experiment... |
3. Iowa Soil-Test Field Calibration Research Update- Potassium and the Mehlich-3 ICP Phosphorus TestIowa soil-test interpretations and fertilizer recommendations for phosphorus (P) and potassium (K) were last updated in 1999. The only change from previous recommendations (Voss et al., 1996; Voss and Mallarino, 1996) was to add interpretations for the Mehlich-3 (M3) P and K tests to existing interpretations for the Bray-1 P, Olsen P, and ammonium-acetate K tests (Voss et al., 1999). The interpretations for the ammonium-acetate and M3 K tests are similar because comparisons of amounts of K extracted... |
4. Soil-Test Potassium Field Calibrations for Soybean Iowa Interpretations and Research UpdateThere is a long history of potassium (K) fertilization research for soybean and other crops in the North-Central Region. Sustained Iowa field research efforts focused on developing soil-test K (ST10 interpretation and on studying impacts of K fertilization strategies on grain yield and STK. Because of changes in the soil-test K method used in Iowa, this information collected over time should be evaluated separately. The field crop response and STK calibration research conducted Erom the late 1960s... |
5. 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... |
6. Swine Manure Phosphorus Use for Crop Production in IowaImproving manure phosphorus (P) management guidelines should result in a more efficient use of thls resource for crop production and in lower risk of P loss to surface water resources. Phosphorus fertilizers are widely used in crop production, there is a great deal of information about their use, and farmers have little doubt about their value to improve crop yield in low- testing soils. However, there is a great deal of uncertainty concerning the value of manure nutrients for crops and about cost-effective... |
7. Aerial Photographs to Guide Corn Fertigation DecisionsCorn producers with pivot irrigatio n have the potential to apply in-season nitrogen (N) fertilizer much more easily than their non-irrigated counterpa rts. A demonstration project was initiated in 2006 to take advantage of this potential. One advantage for in-season N application is that the risk of N loss prior to crop uptake is minimal. Another advantage is the opportunity to diagnose N n eed. A range of studies have shown that N need can vary widely from one field to another, as well as within... |
8. Nitrous Oxide Emissions From Nitrogen Fertilizers In IllinoisNitrous oxide (N 2O) has a large global warming potential (GWP). Agricultural applications of nitrogen (N) contribute to N 2O emissions but it might be possible to mitigate such emissions through different N sources. We investigated the potential for anhydrous ammonia (AA), urea, and polymer coated urea (ESN) to mitigate N 2O emissions while enhancing corn (Zea mays L.) production. This three-year study was conducted in Champaign County, Illinois on highly productive mollisols during 2009 to 2011.... |
9. Crop Sensor-Based N Rates Out-Performed Producer-Chosen N RatesOptimal N fertilizer rate for corn (Zea mays L.) and other crops can vary substantially within and among fields. Current N management practices do not address this variability. Crop reflectance sensors offer the potential to diagnose crop N need and control N application rates at a fine spatial scale. Our objective was to evaluate the performance of sensor-based variable-rate N applications to corn, relative to constant N rates chosen by the producer. Fifty-five replicated on- farm demonstrations... |
10. 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 |
11. Lower Soil Test P Values Do Not Affect Crop Yield Values when Under Conservation PracticesSustainable P management in cropping systems is a challenge in modern agriculture. Phosphorus moving from agricultural fields to aquatic ecosystems resulting in eutrophication and other water quality problems continues to be a challenging issue for the agricultural community to solve. Despite the large amount of P in agricultural soils, most P is held within insoluble complexes, making this pool of P unavailable to plants. The implementation of conservation practices of no-till and high residue... C. Winter, D. Clark, S. Ireland, D. Beck |
12. Corn Response to Sulfur Fertilization in Central Iowa SoilsReductions in atmospheric sulfur (S) deposition and increased S removal through continuous cropping have led to S fertilizer responses in many crops. Responses to S fertilization by corn (Zea mays L.), however, have been inconsistent across the upper Midwest. Our objectives with this field study were to: (i) compare S sources for corn vegetative growth and grain yield; (ii) evaluate soil extractable S and S tissue concentrations at different growth stages as S diagnostic tools;... J. Kovar, C. Crespo, C. Hart, R. Roth, P. O'brien, S. Ruis |