Development of a field worthy sensor system to monitor gaseous nitrogen transfer from agricultural cropland. Phase 1, Final report

摘要

Nitrogen fertilizer accounts for 25 to 33% of the energy requirements in modern crop agriculture in the world today. Energy input for the manufacture of these N fertilizers is in the range of 460 (times) 10(sup 12) Btu per year. Unfortunately, for some N sources up to 70% of this energy in the form of NK can be lost through improper application techniques and poor N management strategies. Anhydrous NH(sub 3) may be lost to the atmosphere during and after placement due to soil conditions placement. Measurement of volatile N is difficult, especially under field conditions. A precise and convenient method of measuring gaseous NH(sub 3) near and above the soil surface is prerequisite to the development and evaluation of alternative fertilizer management strategies and application techniques which can reduce the potential for significant loss. Recent advances in integrated-optic (IO) based sensing offers the potential of measuring low levels of NH(sub 3) loss from a cropping system in the range of 100 ppB. The integrated design of an IO system allows for a more durable device that can be mass produced at low cost. Under Phase I of this project, two IO devices were designed and tested: an absorption device using an oxazine dye as a waveguide coating and an interferometric device using an anilinium salt as a waveguide coating.