Measurement of nitrate-nitrogen concentration in soil based on absorption spectroscopy
First Claim
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1. A device for measuring a nitrate-nitrogen concentration in soil based on attenuation over a spectral operating range, the device comprising:
- a light source that generates light that spans the spectral operating range, the spectral operating range including wavelengths at least as short as 230 nm;
a detector having a sensitivity that spans the spectral operating range;
a sample chamber configured to contain a soil-extractant mixture, the light propagating from the light source to the detector and attenuated by the soil-extractant mixture in the sample chamber, the detector generating a soil spectral signal that indicates the light received by the detector at different wavelengths across the spectral operating range; and
a processor coupled to the detector, wherein the processor estimates an attenuation spectrum of the soil-extractant mixture over the spectral operating range based on the soil spectral signal, and estimates the nitrate-nitrogen concentration based on the attenuation spectrum, wherein the processor, when estimating the attenuation spectrum, removes interference in the soil-extractant mixture using one of spectral deconvolution and curve-fitting.
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Abstract
The nitrate-nitrogen concentration in soil is estimated based on the nitrate-nitrogen 200 nm absorption peak. In one embodiment, a device measures the attenuation spectrum of a soil-extractant mixture over a wavelength range that includes wavelengths in the vicinity of the 200 nm absorption peak (the spectral operating range) and then determines the nitrate-nitrogen concentration based on the attenuation spectrum.
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Citations
22 Claims
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1. A device for measuring a nitrate-nitrogen concentration in soil based on attenuation over a spectral operating range, the device comprising:
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a light source that generates light that spans the spectral operating range, the spectral operating range including wavelengths at least as short as 230 nm; a detector having a sensitivity that spans the spectral operating range; a sample chamber configured to contain a soil-extractant mixture, the light propagating from the light source to the detector and attenuated by the soil-extractant mixture in the sample chamber, the detector generating a soil spectral signal that indicates the light received by the detector at different wavelengths across the spectral operating range; and a processor coupled to the detector, wherein the processor estimates an attenuation spectrum of the soil-extractant mixture over the spectral operating range based on the soil spectral signal, and estimates the nitrate-nitrogen concentration based on the attenuation spectrum, wherein the processor, when estimating the attenuation spectrum, removes interference in the soil-extractant mixture using one of spectral deconvolution and curve-fitting. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for measuring the nitrate-nitrogen concentration in soil based on attenuation over a spectral operating range, the method comprising:
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generating light that spans the spectral operating range and includes wavelengths at least as short as 230 nm; providing a soil-extractant mixture that attenuates the light; detecting the attenuated light; generating a soil spectral signal that indicates the light detected at different wavelengths across the spectral operating range; estimating an attenuation spectrum of the soil-extractant mixture over the spectral operating range based on the soil spectral signal, wherein estimating the attenuation spectrum includes removing interference in the soil-extractant mixture using one of spectral deconvolution and curve-fitting; and estimating the nitrate-nitrogen concentration based on the attenuation spectrum.
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21. A device for measuring the nitrate-nitrogen concentration in soil based on attenuation over a spectral operating range, the device comprising:
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a light source that generates light that spans the spectral operating range, wherein the spectral operating range includes wavelengths at least as short as 230 nm; a detector having a sensitivity that spans the spectral operating range; a sample chamber configured to contain a soil-extractant mixture, wherein the light propagates from the light source to the detector and is attenuated by the soil-extractant mixture in the sample chamber, wherein the detector generates a soil spectral signal that represents the light received by the detector at different wavelengths across the spectral operating range; and a processor coupled to the detector, wherein the processor estimates an attenuation spectrum of the soil-extractant mixture over the spectral operating range based on the soil spectral signal, a reference spectral signal and a dark spectral signal, wherein the processor estimates the nitrate-nitrogen concentration based on the attenuation spectrum.
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22. A method for measuring the nitrate-nitrogen concentration in soil based on attenuation over a spectral operating range, the method comprising:
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generating light that spans the spectral operating range, the spectral operating range including wavelengths at least as short as 230 nm; providing in a sample chamber, a soil-extractant mixture that attenuates the light; detecting the attenuated light with a detector; generating a soil spectral signal that indicates the light detected at different wavelengths across the spectral operating range; estimating an attenuation spectrum of the soil-extractant mixture over the spectral operating range based on the soil spectral signal, a reference spectral signal and a dark spectral signal, wherein the nitrate-nitrogen concentration is estimated based on the attenuation spectrum.
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Specification