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Oltmans, R
Thomas, W.L
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Authors
Lamond, R.E
Thomas, W.L
Whitney, D.A
Maddux, L.D
Gordon, W.B
Martin, V.L
Oltmans, R
Mallarino, A
Topics
Type
Oral
Poster
Year
1994
2018
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1. Nitrogen Management for No-Till Production Systems

Nitrogen management practices including rates and sources were evaluated in high residue no-till production systems involving corn and grain sorghum. A urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT) was evaluated. This research also assessed the impact of type of previous residue on performance of surface applied N. A chlorophyll meter was evaluated as an in-field N assessment tool. Results to date indicate that NBPT is effective in improving the performance of surface broadcast urea....

2. Effects of Sampling Time and Extraction Method on Soil-Test and Nonexchangeable Potassium in Iowa Soils

More research is needed to better understand K cycling and high short-term temporal soil-test K (STK) variation. The objective of this research was to study soil-test K and nonexchangeable K pools across Iowa soils managed with corn-soybean rotations as affected by K application rates, soil properties, parent materials, and time of sampling. Three-year field trials that included a control and several broadcast K fertilizer rates were conducted at 35 Iowa sites. Soil samples (6-inch depth) were... R. Oltmans, A. Mallarino