|Sudduth, Kenneth - Ken|
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2002
Publication Date: 11/1/2002
Citation: SCHARF, P.C., SCHMIDT, J.P., KITCHEN, N.R., SUDDUTH, K.A., HONG, S.Y., LORY, J.A., DAVIS, J.G. REMOTE SENSING FOR NITROGEN MANAGEMENT. JOURNAL OF SOIL AND WATER CONSERVATION. V. 57(6). P. 518-524.
Interpretive Summary: Movement of nitrogen (N) from crop production fields and into ground and surface water remains a challenge for farmers and agronomists. The visual effect of N on crops and the subsequent yield response to inexpensive N fertilizer reinforce farmers' reliance on it for profitable production. While current practices generally are to use one rate of N over a whole field, or even an entire farm, recent evidence shows that crop N need ofte differs dramatically within fields. Consequently, in places where a single N rate exceeds crop need, the left-over N may be lost to the environment. In places where a single rate is less than crop N need, yield will be less than optimal. Remote sensing of fields from airplanes or satellites may help farmers develop appropriate within-field variable-rate N management plans. Soil color is related to soil organic matter level and soil moisture level, both of which can influence the N-supplying ability of the soil. Plant color properties reflect crop N status and soil N availability and can be useful for directing in-season variable-rate N applications. The main advantages of remote sensing for N management are the detail of the information collected and the speed with which information can be collected and assessed over large areas. Limitations of remote sensing for N management include availability, timeliness, susceptibility to weather conditions, and a limited knowledge of how to translate images into management decisions. The information presented here will be useful to producers and crop consultants seeking to improve site-specific nutrient management plans.
Technical 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 on, N management decisions. In particular, 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. This investigation reviews the pros and cons of various remote sensing tools currently being explored to develop variable-rate N management plans. Soil spectral properties (color) are related to soil organic matter level and soil moisture level, both of which can influence the N-supplying ability of the soil. Plant spectral properties reflect crop N status and soil N availability and can be useful for directing in-season variable-rate N applications. Plant color may also be useful for assessing the adequacy o crop N supply achieved with a given N management practice. This paper provides an outline of the current status of these remote sensing approaches, gives examples, discusses several N management contexts in which remote sensing might be used, and considers possible future directions for this technology.