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United States Department of Agriculture

Agricultural Research Service

Title: In Season Crop N Management

Authors
item Shanahan, John
item Raun, W - OKLA STATE UNIV
item Kitchen, Newell

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2005
Publication Date: November 1, 2005
Citation: Shanahan, J.F., Raun, W.F., Kitchen, N.R. 2005. In season crop n management. Agronomy Abstracts.

Interpretive Summary: Traditional nitrogen (N) management schemes for corn production in the USA have resulted in low N use efficiency (NUE), environmental contamination, and considerable public debate regarding use of N fertilizers in crop production. Hence, development of alternative schemes that improve NUE and minimize environmental impact will be crucial to sustaining corn-based farming in the USA. The major causes for low NUE of traditional N management practices are: 1) pre-plant application of large doses of N, and 2) uniform application rates to spatially variable landscapes. This results in N being applied before the time when the crop can effectively utilize N at rates that can exceed crop needs in some field areas, placing N at considerable risk for environmental losses. The use of a soil-based management zone (MZ) approach has been proposed as a means do direct variable N application rates to better match N supply with landscape spatial variation in crop N requirements. However, evidence has accumulated suggesting that the MZ approach alone will not be completely effective in making accurate variable N applications, given the large effect temporal variation in corn belt climate has on expression of spatial variation in crop N needs across years. Others have advocated crop-based strategies that utilize remote sensing of crop canopies to direct in season applications only to landscape areas needing N at times when the crop can most efficiently utilize the N. This presentation will highlight our vision for combining the soil-based MZ and the crop-based remote sensing approaches into an integrated system for making in-season variable N applications under ever changing climatic condition, to more efficiently apply N.

Technical Abstract: Traditional nitrogen (N) management schemes for corn production in the USA have resulted in low N use efficiency (NUE), environmental contamination, and considerable public debate regarding use of N fertilizers in crop production. Hence, development of alternative schemes that improve NUE and minimize environmental impact will be crucial to sustaining corn-based farming in the USA. The major causes for low NUE of traditional N management practices are: 1) pre-plant application of large doses of N, and 2) uniform application rates to spatially variable landscapes. This results in N being applied before the time when the crop can effectively utilize N at rates that can exceed crop needs in some field areas, placing N at considerable risk for environmental losses. The use of a soil-based management zone (MZ) approach has been proposed as a means do direct variable N application rates to better match N supply with landscape spatial variation in crop N requirements. However, evidence has accumulated suggesting that the MZ approach alone will not be completely effective in making accurate variable N applications, given the large effect temporal variation in corn belt climate has on expression of spatial variation in crop N needs across years. Others have advocated crop-based strategies that utilize remote sensing of crop canopies to direct in season applications only to landscape areas needing N at times when the crop can most efficiently utilize the N. This presentation will highlight our vision for combining the soil-based MZ and the crop-based remote sensing approaches into an integrated system for making in-season variable N applications under ever changing climatic condition, to more efficiently apply N.

Last Modified: 12/28/2014
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