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Life Sciences Commons

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Plant Sciences

Selected Works

John E. Sawyer

2016

N fertilizer

Articles 1 - 4 of 4

Full-Text Articles in Life Sciences

Quantifying Corn N Deficiency And Application Rate With Active Canopy Sensors, Daniel W. Barker, John E. Sawyer Jul 2016

Quantifying Corn N Deficiency And Application Rate With Active Canopy Sensors, Daniel W. Barker, John E. Sawyer

John E. Sawyer

Precision agriculture technologies are an integral part of many operations in Iowa corn production. Active canopy sensors have been developed as a tool to determine plant N stress deficiency and provide on-the-go decisions for implementing variable rate N application. The objectives of this study were to assess N deficiency stress levels at the mid-vegetative corn growth stages with active canopy sensors, calibrate active sensors and associated canopy indices, and develop N rate algorithms that can be used to determine variable rate N fertilization.


Post Applied Urea+Agrotain To V10 Corn Field Scale Strip Demonstrations, Daniel W. Barker, John E. Sawyer Jul 2016

Post Applied Urea+Agrotain To V10 Corn Field Scale Strip Demonstrations, Daniel W. Barker, John E. Sawyer

John E. Sawyer

The objectives are to apply N fertilizer when corn rapidly accumulates N and dry matter during the mid-vegetative growth stages and utilize active sensors as a remote sensing method of applying VRT nitrogen.


Evaluation Of Optical Canopy Sensors For In-Season N Rate Management In Corn, Daniel W. Barker, John E. Sawyer Jul 2016

Evaluation Of Optical Canopy Sensors For In-Season N Rate Management In Corn, Daniel W. Barker, John E. Sawyer

John E. Sawyer

Optical canopy sensors are an emerging technology that can serve as a useful in-season N fertilizer management tool for corn (Zea mays L.) production. The sensors provide an estimate of plant biomass and N status at the time of sensing. These growth parameters can be used to make in-season N rate adjustments and variable rate N applications. Currently, a robust and accurate algorithm to determine the appropriate N rate based on canopy sensing is need in order to improve the effectiveness of active sensors in production fields. The objective of this study is to determine the ability of optical canopy …


Active Sensor Strategies For In-Season Application Of Urea In Corn, Daniel W. Barker, John E. Sawyer Jul 2016

Active Sensor Strategies For In-Season Application Of Urea In Corn, Daniel W. Barker, John E. Sawyer

John E. Sawyer

Addition of N fertilizer during the midvegetative corn (Zea Mays L.) stage is being used in Iowa to protect yield potential. The objective of this experiment was to compare pre-plant and in-season N application strategies, and evaluate N use efficiency and grain yield of sensor-based N rate application.