Submitted to: Proceedings of Greek Soil Science Society Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: 9/1/2003
Publication Date: 10/23/2003
Citation: Schepers, J.S. 2003. Crop-based nitrogen management. Proceedings of Greek Soil Science Society Annual Meeting pp 46-55. Interpretive Summary: The occurrence and concentration of nitrate in surface and ground waters are gradually becoming greater concerns throughout society. Since agriculture uses a large portion of the N fertilizer produced in the world, it is appropriate that everyone who uses N fertilizer to grow crops, produces livestock from crops, consumes crop and livestock products, and drinks water should take an interest in N management. The science of making fertilizer recommendations is usually based on various types of soil information that have been correlated with observations of plant response. The problem is that the process is largely proactive in that fertilizer recommendations are frequently based on past responses and adjusted for the soil nutrient status at the beginning of the growing season. As such, N fertilizers are frequently applied several months before crops use them. A crop-based strategy is emerging as an alternative for making improved fertilizer N recommendations. This reactive strategy uses crop vigor to assess the need for additional nutrients. Tools required to make this approach feasible include global positioning system (GPS) and remote sensing technologies. Theoretically, more intensive management is required to make the crop-based approach reliable, but new types of crop and soil sensors are helping bring this concept to reality.
Technical Abstract: Nitrogen (N) is the most abundant nutrient in plants and one of the most difficult to manage because the economic and environmental implications are frequently at odds. The fact that N in the nitrate form is soluble in water makes it a potential contaminant of surface and ground water. In reality, the emphasis placed on N management is typically related to profitability for the end user unless other segments of society are negatively impacted. Individuals and businesses involved in the supply and distribution of N fertilizers to producers have a vested interest in how the N is managed because it impacts their livelihood. In the long term, everyone involved in the N supply and management chain has a vested interest in doing what he or she can to promote the efficient use of N, be it from fertilizers, manure, or soil organic matter. This responsibility extends to the scientific community because that entity provides the information that links the various chemical, physical, and biological processes involved in N use and management to producer practices. A crop-based N management strategy is emerging as GIS and remote sensing tools become available. This approach offers economic and environmental advantages over the existing soil-based approach for making fertilizer N recommendations. Regardless of the N management strategy, it is obvious that temporal and spatial considerations will need to play an increasingly larger role in the future.