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Physical Sciences and Mathematics Commons

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Oceanography and Atmospheric Sciences and Meteorology

Selected Works

John E. Sawyer

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Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

United States Midwest Soil And Weather Conditions Influence Anaerobic Potentially Mineralizable Nitrogen, Jason D. Clark, Kristen S. Veum, Fabián G. Fernández, James J. Camberato, Paul R. Carter, Richard B. Ferguson, David W. Franzen, Daniel E. Kaiser, Newell R. Kitchen, Carrie A. M. Laboski, Emerson D. Nafziger, Carl J. Rosen, John E. Sawyer, John F. Shanahan Sep 2019

United States Midwest Soil And Weather Conditions Influence Anaerobic Potentially Mineralizable Nitrogen, Jason D. Clark, Kristen S. Veum, Fabián G. Fernández, James J. Camberato, Paul R. Carter, Richard B. Ferguson, David W. Franzen, Daniel E. Kaiser, Newell R. Kitchen, Carrie A. M. Laboski, Emerson D. Nafziger, Carl J. Rosen, John E. Sawyer, John F. Shanahan

John E. Sawyer

Nitrogen provided to crops through mineralization is an important factor in N management guidelines. Understanding of the interactive effects of soil and weather conditions on N mineralization needs to be improved. Relationships between anaerobic potentially mineralizable N (PMNan) and soil and weather conditions were evaluated under the contrasting climates of eight US Midwestern states. Soil was sampled (0–30 cm) for PMNan analysis before pre-plant N application (PP0N) and at the V5 development stage from the pre-plant 0 (V50N) and 180 kg N ha−1 (V5180N) rates and incubated for 7, 14, …


Corn And Soybean Response To Sulfur Application On Iowa Soils, J. E. Sawyer, D. W. Barker Apr 2017

Corn And Soybean Response To Sulfur Application On Iowa Soils, J. E. Sawyer, D. W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for com and soybean production. Prior research has not determined a consistent need for S fertilization in Iowa, with field research indicating no com or soybean yield response to applied S at virtually every site studied (Thorup and Leitch 1975; Webb, 1978; Alesii 1982; Killorn, 1984; Sexton et al., 1998; Mallarino et al., 2000). The soil supply, in combination with sources such as manure and atmospheric deposition has apparently met com and soybean S needs. Sulfur deficiencies have been reported over the years in various areas of the Midwestern …


Drought Impacts On Soil Fertility Management, John E. Sawyer Jul 2016

Drought Impacts On Soil Fertility Management, John E. Sawyer

John E. Sawyer

If crop production was severely reduced because of dry conditions this year, there are a few items you can consider when planning for next year's crop. One, with severely damaged crops and low yields you might credit some of the phosphorus (P) and potassium (K) applied for this year's crop to next year, as much less removal will occur in grain harvest of the lower than expected yield.