Spectral Analysis and Sensitive Waveband Determination Based on Nitrogen Detection of Different Soil Types Using Near Infrared Sensors

Compared with the chemical analytical technique, the soil nitrogen acquisition method based on near infrared (NIR) sensors shows significant advantages, being rapid, nondestructive, and convenient. Providing an accurate grasp of different soil types, sensitive wavebands could enhance the nitrogen es...

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Main Authors: Shupei Xiao, Yong He, Tao Dong, Pengcheng Nie
Format: Article
Language:English
Published: MDPI AG 2018-02-01
Series:Sensors
Subjects:
Online Access:http://www.mdpi.com/1424-8220/18/2/523
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author Shupei Xiao
Yong He
Tao Dong
Pengcheng Nie
author_facet Shupei Xiao
Yong He
Tao Dong
Pengcheng Nie
author_sort Shupei Xiao
collection DOAJ
description Compared with the chemical analytical technique, the soil nitrogen acquisition method based on near infrared (NIR) sensors shows significant advantages, being rapid, nondestructive, and convenient. Providing an accurate grasp of different soil types, sensitive wavebands could enhance the nitrogen estimation efficiency to a large extent. In this paper, loess, calcium soil, black soil, and red soil were used as experimental samples. The prediction models between soil nitrogen and NIR spectral reflectance were established based on three chemometric methods, that is, partial least squares (PLS), backward interval partial least squares (BIPLS), and back propagation neural network (BPNN). In addition, the sensitive wavebands of four kinds of soils were selected by competitive adaptive reweighted sampling (CARS) and BIPLS. The predictive ability was assessed by the coefficient of determination R2 and the root mean square error (RMSE). As a result, loess ( 0.93 < R p 2 < 0.95 , 0.066 g / kg < RMSE p < 0.075 g / kg ) and calcium soil ( 0.95 < R p 2 < 0.96 , 0.080 g / kg < RMSE p < 0.102 g / kg ) achieved a high prediction accuracy regardless of which algorithm was used, while black soil ( 0.79 < R p 2 < 0.86 , 0.232 g / kg < RMSE p < 0.325 g / kg ) obtained a relatively lower prediction accuracy caused by the interference of high humus content and strong absorption. The prediction accuracy of red soil ( 0.86 < R p 2 < 0.87 , 0.231 g / kg < RMSE p < 0.236 g / kg ) was similar to black soil, partly due to the high content of iron–aluminum oxide. Compared with PLS and BPNN, BIPLS performed well in removing noise and enhancing the prediction effect. In addition, the determined sensitive wavebands were 1152 nm–1162 nm and 1296 nm–1309 nm (loess), 1036 nm–1055 nm and 1129 nm–1156 nm (calcium soil), 1055 nm, 1281 nm, 1414 nm–1428 nm and 1472 nm–1493 nm (black soil), 1250 nm, 1480 nm and 1680 nm (red soil). It is of great value to investigate the differences among the NIR spectral characteristics of different soil types and determine sensitive wavebands for the more efficient and portable NIR sensors in practical application.
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spelling doaj.art-5fafb1cc964e41ee823d116ffcec83502022-12-22T02:53:47ZengMDPI AGSensors1424-82202018-02-0118252310.3390/s18020523s18020523Spectral Analysis and Sensitive Waveband Determination Based on Nitrogen Detection of Different Soil Types Using Near Infrared SensorsShupei Xiao0Yong He1Tao Dong2Pengcheng Nie3College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, ChinaCollege of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, ChinaCollege of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, ChinaCollege of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, ChinaCompared with the chemical analytical technique, the soil nitrogen acquisition method based on near infrared (NIR) sensors shows significant advantages, being rapid, nondestructive, and convenient. Providing an accurate grasp of different soil types, sensitive wavebands could enhance the nitrogen estimation efficiency to a large extent. In this paper, loess, calcium soil, black soil, and red soil were used as experimental samples. The prediction models between soil nitrogen and NIR spectral reflectance were established based on three chemometric methods, that is, partial least squares (PLS), backward interval partial least squares (BIPLS), and back propagation neural network (BPNN). In addition, the sensitive wavebands of four kinds of soils were selected by competitive adaptive reweighted sampling (CARS) and BIPLS. The predictive ability was assessed by the coefficient of determination R2 and the root mean square error (RMSE). As a result, loess ( 0.93 < R p 2 < 0.95 , 0.066 g / kg < RMSE p < 0.075 g / kg ) and calcium soil ( 0.95 < R p 2 < 0.96 , 0.080 g / kg < RMSE p < 0.102 g / kg ) achieved a high prediction accuracy regardless of which algorithm was used, while black soil ( 0.79 < R p 2 < 0.86 , 0.232 g / kg < RMSE p < 0.325 g / kg ) obtained a relatively lower prediction accuracy caused by the interference of high humus content and strong absorption. The prediction accuracy of red soil ( 0.86 < R p 2 < 0.87 , 0.231 g / kg < RMSE p < 0.236 g / kg ) was similar to black soil, partly due to the high content of iron–aluminum oxide. Compared with PLS and BPNN, BIPLS performed well in removing noise and enhancing the prediction effect. In addition, the determined sensitive wavebands were 1152 nm–1162 nm and 1296 nm–1309 nm (loess), 1036 nm–1055 nm and 1129 nm–1156 nm (calcium soil), 1055 nm, 1281 nm, 1414 nm–1428 nm and 1472 nm–1493 nm (black soil), 1250 nm, 1480 nm and 1680 nm (red soil). It is of great value to investigate the differences among the NIR spectral characteristics of different soil types and determine sensitive wavebands for the more efficient and portable NIR sensors in practical application.http://www.mdpi.com/1424-8220/18/2/523soil nitrogenNIR sensorssensitive wavebandsPLSBIPLSBPNNCARS
spellingShingle Shupei Xiao
Yong He
Tao Dong
Pengcheng Nie
Spectral Analysis and Sensitive Waveband Determination Based on Nitrogen Detection of Different Soil Types Using Near Infrared Sensors
Sensors
soil nitrogen
NIR sensors
sensitive wavebands
PLS
BIPLS
BPNN
CARS
title Spectral Analysis and Sensitive Waveband Determination Based on Nitrogen Detection of Different Soil Types Using Near Infrared Sensors
title_full Spectral Analysis and Sensitive Waveband Determination Based on Nitrogen Detection of Different Soil Types Using Near Infrared Sensors
title_fullStr Spectral Analysis and Sensitive Waveband Determination Based on Nitrogen Detection of Different Soil Types Using Near Infrared Sensors
title_full_unstemmed Spectral Analysis and Sensitive Waveband Determination Based on Nitrogen Detection of Different Soil Types Using Near Infrared Sensors
title_short Spectral Analysis and Sensitive Waveband Determination Based on Nitrogen Detection of Different Soil Types Using Near Infrared Sensors
title_sort spectral analysis and sensitive waveband determination based on nitrogen detection of different soil types using near infrared sensors
topic soil nitrogen
NIR sensors
sensitive wavebands
PLS
BIPLS
BPNN
CARS
url http://www.mdpi.com/1424-8220/18/2/523
work_keys_str_mv AT shupeixiao spectralanalysisandsensitivewavebanddeterminationbasedonnitrogendetectionofdifferentsoiltypesusingnearinfraredsensors
AT yonghe spectralanalysisandsensitivewavebanddeterminationbasedonnitrogendetectionofdifferentsoiltypesusingnearinfraredsensors
AT taodong spectralanalysisandsensitivewavebanddeterminationbasedonnitrogendetectionofdifferentsoiltypesusingnearinfraredsensors
AT pengchengnie spectralanalysisandsensitivewavebanddeterminationbasedonnitrogendetectionofdifferentsoiltypesusingnearinfraredsensors