Estimating texture and organic carbon of an Oxisol by near infrared spectroscopy<sup/>

Fernández-Martínez, Felipe; Camacho-Tamayo, Jesús Hernán; Rubiano-Sanabria, Yolanda

doi:10.5935/1806-6690.20220020

Acessibilidade / Reportar erro

Brasil

Revista Ciência Agronômica

Español English

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Scientific Article • Rev. Ciênc. Agron. 53 • 2022 • https://doi.org/10.5935/1806-6690.20220020 copy

Estimating texture and organic carbon of an Oxisol by near infrared spectroscopy¹ 1 Research project from the Bogotá headquarters Research Division of Universidad Nacional de Colombia

Estimación de textura y carbono orgánico de un Oxisol mediante espectroscopia de infrarrojo cercano

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Laboratory analyses are a fundamental basis for monitoring soil behavior. These analyses are usually tedious and expensive depending on the methodology used, which may limit data acquisition. The aim of this research was to evaluate the potential of Near Infrared (NIR) diffuse reflectance spectroscopy for the estimation of texture and Soil Organic Carbon (SOC) of an Oxisol. A total of 313 samples were collected at fixed depths of 0.0-0.10, 0.10-0.20, 0.20-0.30, 0.30-0.40 and 0.40-0.50 m in 70 points distributed in 248 ha, from which SOC and the fractions of sand, silt and clay were determined. The spectral signatures were obtained from a NIRFlex sensor, and the modeling was done applying partial least squares regression. A highly representative model was obtained for the SOC estimation, with a coefficient of determination (R²) of 0.97, Root Mean Square Error (RMSE) of 1.10 g kg^-1 and Residual Prediction Deviation (RPD) of 5.63. For the textural fractions, estimation models of lesser performance were obtained, with R²values of 0.62; 0.44 and 0.62, RMSE values of 1.10%, 2.92% and 3.08%, and RPD values of 1.82, 1.61 and 1.81 for sand, silt and clay, respectively. By means of geostatistical interpolation surfaces, the behavior of the measured and spectrally estimated variables was compared. NIR spectroscopy proved to be a viable alternative for the precise estimation of SOC, while for the textural fractions it is convenient to explore the improvement of the estimates.

Key words:
NIR spectroscopy; Pedometrics; Spectral modelling; Geostatistics; Chemometrics

Property	Unit	Depth [m]	Mean	Minimum	Maximum	SD	CV
SOC	g kg^-1	0.0-0.10	26.15	19.76	32.41	0.26	10.08
		0.10-0.20	17.49	13.30	21.57	0.18	10.51
		0.20-0.30	13.87	10.76	17.53	0.16	11.33
		0.30-0.40	11.24	8.46	15.04	0.17	14.78
		0.40-0.50	9.53	5.77	13.11	0.16	16.50
Sand	%	0.0-0.10	6.45	1.85	9.65	2.04	31.82
		0.10-0.20	4.47	1.53	7.53	1.44	32.26
		0.20-0.30	3.16	1.00	5.29	1.03	32.23
		0.30-0.40	2.72	1.03	5.00	0.94	33.68
		0.40-0.50	2.39	1.18	3.83	0.78	33.43
Silt	%	0.0-0.10	74.63	66.22	82.37	3.44	4.64
		0.10-0.20	73.89	63.44	83.89	4.28	5.81
		0.20-0.30	71.85	62.13	82.34	4.37	6.08
		0.30-0.40	69.40	60.47	81.60	4.69	6.73
		0.40-0.50	67.80	60.53	75.10	3.75	5.55
Clay	%	0.0-0.10	18.92	11.21	26.46	3.42	17.87
		0.10-0.20	21.64	11.77	32.23	4.39	20.06
		0.20-0.30	24.99	13.69	35.62	4.70	18.99
		0.30-0.40	27.88	16.96	36.71	4.26	15.28
		0.40-0.50	29.81	22.90	36.91	3.74	12.55

Property	Unit	Calibration				Validation
Property	Unit	Range	RMSE	R2	RPD	Range	RMSE	R2	RPD
SOC	g kg^-1	5.77-32.41	1.14	0.97	5.46	7.48 - 32.40	1.10	0.97	5.63
Sand	%	1.00 - 9.65	1.13	0.69	1.76	1.03 - 9.50	1.10	0.62	1.82
Silt	%	60.47 - 82.37	3.03	0.59	1.56	64.24 - 82.34	2.92	0.44	1.61
Clay	%	11.77 - 36.91	3.12	0.70	1.79	11.21 - 33.80	3.08	0.62	1.81

Model/ Property	Unit	β Coefficient considered	Spectral bands with the greatest influence on the model	Number of spectral bands
SOC	g kg^-1	β ≥ 0.03;-0.03 ≥ β	1410-1418, 1869-1876, 2017-2065, 2155-2176, 2200-2207, 2210-2219, 2234-2279, 2312-2322, 2351-2359	163
Sand	%	β ≥ 150;-150 ≥ β	1410-1413, 1875-1876, 1909-1926, 2029-2053, 2168-2174, 2234-2269, 2314-2322, 2351-2361, 2448-2454	110
Silt	%	β ≥ 1.0;-1.0 ≥ β	1395-1416, 1430-1453, 2145-2159, 2189-2197, 2204-2211, 2218-2277, 2487-2495	140
Clay	%	β ≥ 1.0;-1.0 ≥ β	1395-1410, 1895-1913, 2145-2159, 2189-2211, 2218-2284, 2376-2397	156

Property	Depth [m]	Semivariogram model	C0	C0 + C1	Range [m]	CVC	R2	DSD [%]
Measured SOC [g kg^-1]	0.00-0.10	Exponential	2.1E^-2	5.9E^-2	753	0.73	0.95	65
	0.10-0.20	Spherical	1.5E^-2	3.3E^-2	1046	0.72	0.96	56
	0.20-0.30	Spherical	8.1E^-3	2.0E^-2	695	0.85	0.83	59
	0.30-0.40	Exponential	1.1E^-2	2.7E^-2	711	0.77	0.90	59
	0.40-0.50	Spherical	1.0E^-2	2.4E^-2	538	0.76	0.91	58
Estimated SOC [g kg^-1]	0.00-0.10	Spherical	1.6E^-1	1.2E⁺⁰	582	0.81	0.94	87
	0.10-0.20	Exponential	1.5E^-1	3.8E^-1	828	0.79	0.97	60
	0.20-0.30	Exponential	7.3E^-2	1.8E^-1	760	0.71	0.99	58
	0.30-0.40	Spherical	4.6 E^-2	1.7E^-1	641	0.87	0.88	72
	0.40-0.50	Spherical	2.6E^-2	1.0E^-1	490	0.94	0.85	75
Measured sand [%]	0.00-0.10	Exponential	1.20	4.12	700	0.71	0.96	71
	0.10-0.20	Exponential	0.65	1.84	600	0.71	0.95	65
	0.20-0.30	Spherical	0.47	0.98	391	0.89	0.74	52
	0.30-0.40	Exponential	0.29	0.73	950	0.90	0.85	60
	0.40-0.50	Spherical	0.16	0.49	427	0.78	0.87	67
Estimated sand [%]	0.00-0.10	Spherical	0.16	1.24	582	0.81	0.94	87
	0.10-0.20	Exponential	0.15	0.38	828	0.79	0.97	60
	0.20-0.30	Exponential	0.07	0.18	760	0.71	0.99	58
	0.30-0.40	Spherical	0.05	0.17	641	0.87	0.88	72
	0.40-0.50	Spherical	0.03	0.10	490	0.94	0.85	75

Property	Depth [m]	Semivariogram model	C0	C0+C1	Range [m]	CVC	R2	DSD [%]
Measured silt [%]	0.00-0.10	Spherical	3.50	11.50	635	1.00	0.92	70
	0.10-0.20	Spherical	8.67	21.29	1029	0.85	0.95	59
	0.20-0.30	Spherical	8.15	19.12	763	0.79	0.96	57
	0.30-0.40	Spherical	6.29	21.94	575	0.88	0.92	71
	0.40-0.50	Spherical	4.17	16.93	891	0.91	0.97	75
Estimated silt [%]	0.00-0.10	Spherical	0.63	2.08	672	0.87	0.98	70
	0.10-0.20	Spherical	0.33	4.26	685	0.82	0.94	92
	0.20-0.30	Spherical	2.93	8.27	793	0.70	0.92	65
	0.30-0.40	Exponential	4.56	12.60	706	0.78	0.81	64
	0.40-0.50	Spherical	2.93	8.81	739	0.73	0.88	67
Measured clay [%]	0.00-0.10	Spherical	5.73	12.30	1230	0.93	0.97	53
	0.10-0.20	Spherical	9.06	20.60	1177	0.79	0.91	56
	0.20-0.30	Spherical	10.96	25.13	912	0.80	0.94	56
	0.30-0.40	Spherical	1.35	19.68	448	0.86	0.92	93
	0.40-0.50	Spherical	7.39	14.79	1171	0.99	0.91	50
Estimated clay [%]	0.00-0.10	Spherical	0.87	3.37	677	0.89	0.88	74
	0.10-0.20	Spherical	0.24	5.22	650	0.85	0.85	95
	0.20-0.30	Spherical	3.15	11.50	900	0.82	0.97	73
	0.30-0.40	Spherical	4.14	11.37	513	0.79	0.99	64
	0.40-0.50	Spherical	2.91	7.35	748	0.69	0.93	60

Universidade Federal do Ceará Av. Mister Hull, 2977 - Bloco 487, Campus do Pici, 60356-000 - Fortaleza - CE - Brasil, Tel.: (55 85) 3366-9702 / 3366-9732, Fax: (55 85) 3366-9417 - Fortaleza - CE - Brazil
E-mail: ccarev@ufc.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] *Author for correspondence

Brasil

Brasil

Estimating texture and organic carbon of an Oxisol by near infrared spectroscopy1 1 Research project from the Bogotá headquarters Research Division of Universidad Nacional de Colombia

Estimación de textura y carbono orgánico de un Oxisol mediante espectroscopia de infrarrojo cercano

ABSTRACT

Estimating texture and organic carbon of an Oxisol by near infrared spectroscopy¹ 1 Research project from the Bogotá headquarters Research Division of Universidad Nacional de Colombia