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| Filter results3 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. 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 |
3. Cropping System Diversification Has Strong Short-term but Limited Long-term Impacts on Soil Phosphorus DynamicsCrop diversification provides several agroecosystem benefits, yet the effects of extended crop rotations and livestock integration on soil phosphorus (P) dynamics are not well understood. We examined the effect of three cropping systems: a corn (Zea mays L.)-soybean (Glycine max (L.) Merr.) rotation with synthetic fertilizer (2 year), a corn-soybean-small grain rotation with red clover (Trifolium pratense L.) and composted cattle manure as a fertilizer source (3 year),... J. Kovar, C. Crespo, J. Berkey, P. O'brien, W. Huang, M. Liebman, M. Mcdaniel |