ABSTRACT:
Nitrogen application often dramatically increases crop yields, but N needs vary spatially across fields and landscapes. Remote sensing collects spatially dense information that may contribute to, or provide feedback about, N management decisions. There is potential to accurately predict N fertilizer need at each point in the field. This would reduce surplus N in the crop production system without reducing crop yield, which would in turn reduce N losses to surface and ground waters. Soil spectral properties (color) are related to soil organic matter and soil moisture levels, factors that influence the N-supplying ability of the soil. Plant spectral properties reflect crop N status and soil N availability, and they can be useful for directing in-season variable-rate N applications. Plant color may also be useful for assessing the adequacy of crop nitrogen supply achieved with a given nitrogen management practice. We outline the current status of these approaches, offer examples, discuss several N management contexts in which these approaches might be used, and consider possible future directions for this technology.
Footnotes
Peter C. Scharf, John A. Lory, and J. Glenn Davis are with the University of Missouri in Columbia, Missouri. John P. Schmidt is with Kansas State University in Manhattan, Kansas. Newell R. Kitchen and Kenneth A. Sudduth are with the U.S. Department of Agriculture's Agricultural Research Service in Columbia, Missouri. S. Young Hong is with the National Institute of Agricultural Science and Technology in Suwon, Korea.
- Copyright 2002 by the Soil and Water Conservation Society
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