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Sawyer, J.E
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Authors
Sawyer, J.E
Pantoja, J.L
Barker, D.W
Sawyer, J.E
Sawyer, J.E
Barker, D.W
Lundvall, J.P
Al-Kaisi, M
Nafziger, E.D
Sawyer, J.E
Hoeft, R.G
Sawyer, J.E
Nafziger, E.D
Sawyer, J.E
Lundvall, J.P
Hawkins, J.A
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Type
Oral
Year
2014
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1. Grid Sampling- The Worth of Information

Soil sample collection and chemical analysis is a time honored, scientific procedure for providing information used in determining limestone and nutrient needs in crop production fields. Ln fact, without that information one cannot make appropriate limestone and nutrient input decisions. At best they would be educated guesses. and most likely would be incorrect. Inherently then, in the soil testing process is a worth of the information derived. This worth is dependent upon the test results and the...

2. Evaluation of the Amino Sugar-N Based Soil test in Iowa Corn Production

An important improvement in estimating economic N applications for corn production would be to predict the soil N supply capacity each year. The objective of this research is to evaluate the adaptability and potential calibration of the amino sugar-N based Illinois N Soil Test in corn production fields across diverse Iowa soils. Nitrogen rate trials were conducted at multiple sites over several years, many on producer fields. Soil samples were collected at 0-6 and 0-12 inch depths in the fall and...

3. Formulating N Recommendations for Corn in the Corn Belt Using Recent Data

Making N rate recommendations for corn has been one of the most econonlically important goals of publicly funded crop production and soil fertility personnel and programs over the past five decades. Changes in cropping systems, hybrids, tillage, and other management practices, along with opportunities in site-specific inputs and awareness of the need to minimize the amount of N that reaches surface and ground waters have combined to increase the interest to re-exanline N rate recommendations, and...

4. Regional Approach to Making Nitrogen Fertilizer Rate Decisions for Corn

Nitrogen fertilizer is one of the largest input costs for growing corn. Across the Corn Belt, N is typically the most yield-limiting nutrient. Facing record high N fertilizer prices and potential supply problems, producers are concellled about N fertilization rates. Soil fertility researchers and extension specialists froin seven states across the Corn Belt (see list in acknowledgements section) have been discussing corn N fertilization needs and evaluating N rate recommendation systems for approxinlately...

5. In-Season Nitrogen Management for Corn Production

Water quality impairment related to nitrogen (N) continues to be a concern in Iowa, including the nitrate drinking water standard, USEPA proposed surface water quality nutrient criteria, and the Gulf of Mexico hypoxia. Addressing these issues could include strict guidance for N input to corn and resultant N use practices that require very high level of management and risk, with unknown economic consequences. Rate of N application is an important ma nagement factor in corn production related to nitrat...

6. Corn Nitrogen Rate Response and Crop Yield in a Rye Cover Crop System

Water quality impairment related to N loss from crop production fields continues to be a concern in Iowa, including meeting the USEPA nitrate-N drinking water standard and reducing N export to the Gulf of Mexico. Therefore, in-field production practices would be helpful to aid in reduction of nitrate leaching and movement to water systems. One practice identified in the science assessment for the Iowa Nutrient Reduction Strategy is use of a winter cereal rye (Secale cereal L.) cover crop, where a...