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| Filter results8 paper(s) found. |
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1. Soil Mineralogy and Potassium AvailabilityIn this talk, I will try to answer four questions. The outline below gives the overall framework for the presentation. 1. What are the mineral sources of potassium? Primary minerals crystallize from the magma. Those that contain K are: Feldspars (microcline and orthoclase) Micas (biotite and muscovite) Primary minerals weather decompose by several mechanisms. Chemical bonds are destabilized by acid attack. Al ions are complexed by organic... M.L. Thompson |
2. Effect of Ammonium to Nitrate Rations of Fertilizers Applied at Various Times Throughout the Growing Season on Yield and Nitrogen Concentrationof CornA number of recent investigations have produced evidenm that the ionic form of N taken up by roots affects the growth of plants. While soil- plants generally take up rest of their N as nitrate, there is evidence that increasing the relative proportion of ammonium in the culture (or soil) solution can enhance growth and yield. Owing to difficulties in prevent* the rapid miaxbial conversion of ammonium to nitrate in soil, this response has nat been well demnstrated in a field situation. The objective... |
3. Yield and N Concentraions of Corn with Different N Sources Applied at Different timesA number of recent investigations have produced evidence that the ionic form of N taken up by roots affects the growth of plants. While soil- grown plants generally take up most of their N as nitrate, there is evidence that increasing the relative proportion of ammonium in the culture (or soil) solution can enhance growth and yield. Owing to difficulties in preventing the rapid microbial conversion of ammonium to nitrate in soil, this response has not been well demonstrated in a field situation.... |
4. Variable Fertilizer Nitrogen Application Based on the Delta Yield Index- A Field StudyA quick review of the both the scientific and popular literature indicates that many different approaches have been suggested for the prediction of variable fertilizer N applications in the field. In previous meetings of this conference we have presented the general outline and approach taken for our site-specific crop management project in Ontario. Briefly, historical data sets of grain corn response trials to fertilizer N (encompassing some 300 site-years worth of data) indicated that most yield... |
5. 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 |
6. Practical Farmers of Iowa On-farm Research ProgramPractical Farmers of Iowa (PFI) has been leading and conducting on-farm research since 1987. The organization has staff scientists to help design experiments based on questions from participating farmers. Farmers are cooperators in research and they often collaborate with other farmers on the same project. Ideas for projects are considered at the annual Cooperators’ Meeting in December each year. Cooperators describe what was done on their farm, why they did it, and what they found. They... S. Gailans |
7. Investigating the Effects of Tillage Practices and Fertilizer Placement Strategies on Corn Yield and Nutrient Uptake in Eastern South DakotaIn South Dakota, phosphorus (P) and potassium (K) fertilizers are often used to optimize corn (Zea may L.) grain yields and maintain soil fertility. The placement of these fertilizers often has an impact on the nutrient accessibility to the plant and the fertilizer’s impact on the environment. The management of these fertilizers is largely influenced by the tillage system utilized. In the western corn belt, producers have historically used a combination of conventional and... C. Tesch, P. Kovacs |
8. Two-sided Banding of Nitrogen and Sulfur Fertilizers Improves Maize Yield and Nutrient Use Efficiency in Midwestern Cropping SystemsEfficient fertilizer management is essential for maximizing crop yield while minimizing environmental impacts. Optimizing fertilizer placement is a key strategy for improving nutrient recovery and synchronizing nutrient availability with crop demand. Traditionally, fertilizer banding in Midwestern maize (Zea mays L.) systems is done on one side of the plant. This study evaluates the impact of two-sided banding of nitrogen (N) and sulfur (S) fertilizers on maize yield and nutrient use... A. Yakubu, A. Ludolph, A. Diop, A. Yakubu, R. Roth |