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ARS Home » Plains Area » Lincoln, Nebraska » Agroecosystem Management Research » Research » Publications at this Location » Publication #254004
Title: A Crop and Soil Strategy for Sensor-Based Variable-Rate Nitrogen Management

Author
item ROBERTS, DARRIN - Mississippi State University
item Shanahan, John
item FERGUSON, RICHARD - University Of Nebraska
item ADAMCHUK, VIACHESLAV - University Of Nebraska
item Kitchen, Newell

Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/7/2010
Publication Date: 7/19/2010
Citation: Roberts, D.F., Shanahan, J.F., Ferguson, R.B., Adamchuk, V.I., Kitchen, N.R. 2010. A Crop and Soil Strategy for Sensor-Based Variable-Rate Nitrogen Management. International Conference on Precision Agriculture Abstracts & Proceedings.

Interpretive Summary: The development of alternative N management strategies is crucial for sustaining future corn production in the United States and around the world, because current N management approaches have led to low nitrogen use efficiency (NUE), economic losses, and environmental contamination issues. Crop-based active canopy sensors and soil-based management zones (MZ) are currently being studied as tools to direct in-season variable-rate N application. Some have suggested the integration of these tools as a more robust decision tool for guiding spatially variable N rates. Hence, the objectives of this study were to identify (1) soil variables useful for MZ delineation and (2) determine if MZ could be useful in identifying field areas with differential crop response to N and hence be effective in guiding spatially variable N applications in addition to crop canopy sensing. In order to address the study objectives, Eight N rates (0 to 274 kg ha-1 in 39 kg ha-1 increments) were applied in replicated small plots across an irrigated cornfield in central Nebraska in 2007. Soil variables evaluated for MZ delineation included maps of apparent soil electrical conductivity (ECa), soil optical reflectance, and landscape topography. Crop response to N was determined via active sensor assessments of in-season canopy reflectance (chlorophyll index; CI) and grain yield measurements. The relationships between soil and crop response variables were evaluated, and selected soil variables were used to delineate MZ. Crop responses had the highest correlation to ECa and relative elevation (Elevrel). Economic analysis showed potential benefits to N management using soil-based MZ compared to the current producer N rate for this field. Further economic benefits could potentially be achieved by integrating soil-based MZ and in-season sensor-based N application.

Technical Abstract: Crop-based active canopy sensors and soil-based management zones (MZ) are currently being studied as tools to direct in-season variable-rate N application. Some have suggested the integration of these tools as a more robust decision tool for guiding spatially variable N rates. The objectives of this study were to identify (1) soil variables useful for MZ delineation and (2) determine if MZ could be useful in identifying field areas with differential crop response to N and hence be effective in guiding spatially variable N applications in addition to crop canopy sensing. Eight N rates (0 to 274 kg ha-1 in 39 kg ha-1 increments) were applied in replicated small plots across an irrigated cornfield in central Nebraska in 2007. Soil variables evaluated for MZ delineation included maps of apparent soil electrical conductivity (ECa), soil optical reflectance, and landscape topography. Crop response to N was determined via active sensor assessments of in-season canopy reflectance (chlorophyll index; CI590) and grain yield measurements. The relationships between soil and crop response variables were evaluated, and selected soil variables were used to delineate MZ. Crop response had the highest correlation to ECa and relative elevation (Elevrel). Economic analysis showed potential benefits to N management using soil-based MZ compared to the current producer N rate for this field. Further economic benefits could potentially be achieved by integrating soil-based MZ and in-season sensor-based N application.