TY - JOUR
T1 - Optical assessment of the spatial variation in total soil carbon using laser-induced breakdown spectroscopy
AU - Dwivedi, Vishal
AU - Ahokas, Joni
AU - Viljanen, Jan
AU - Ryczkowski, Piotr
AU - Shurpali, Narasinha J.
AU - Raj Bhattarai, Hem
AU - Virkajärvi, Perttu
AU - Toivonen, Juha
N1 - Funding Information:
The authors are grateful for the collaboration over the Carbon Action platform. This work was supported by the Academy of Finland Flagship Programme PREIN (grant 320165) and the Ministry of Agriculture and Forestry of Finland (decisions VN/5275/2021 ). J.V. and N.J.S. acknowledge funding from the Academy of Finland (decisions: 338338 and 334422 ). P.V. and N.J.S. also acknowledge funding from the Ministry of Agriculture and Forestry of Finland, ORMINURMI , ORMINURMI 2 , and NC-GRASS ( VN/28562/2020-MMM-2 ).
Publisher Copyright:
© 2023 The Author(s)
PY - 2023/8
Y1 - 2023/8
N2 - Soil carbon storage is a substantial factor in the global carbon cycle. Carbon sequestration in agricultural soils, and the assessment and validation of soil carbon storage, are crucial for the mitigation of agricultural greenhouse gas emissions and for steering towards sustainable farming practices. Enforcement and verification of carbon sequestration policies, methods, and models require extensive soil carbon monitoring capability. However, current conventional laboratory-based methods for soil carbon estimation are laborious, expensive, and time-consuming. In this work, we have developed a compact, robust, and field-capable experimental device based on laser-induced breakdown spectroscopy (LIBS) for the rapid assessment of total soil carbon content and its spatial distribution in mineral soils. The carbon content quantification was performed using a spectral line of carbon at a wavelength of 193.1 nm emitted from the laser-induced plasma plume. The LIBS measurements were performed on soil samples collected from 28 different locations and various depths (up to 1 m) of a test field cultivated with a forage legume (red clover - Trifolium pratense, L.) and grass (Timothy - Phleum pratense, L.) mixture in eastern Finland. A calibration model was established based on a limited and randomly chosen sample set and validated by comparing soil carbon estimates obtained from various locations in the test field using the dry combustion (LECO) method. Further, we demonstrate here the usefulness of LIBS methodology for mapping three-dimensional carbon distribution at the test field. We emphasize here that the calibration model can be generalized to other sample areas under similar soil type with a relative error of less than 10 % and possesses potential for fast on-site determination of spatial variation in total soil carbon, reducing substantially the need of time-consuming sample processing in laboratory. Therefore, LIBS enables frequent and extensive spatial and temporal soil carbon mapping and has the potential to become part of the future carbon monitoring network.
AB - Soil carbon storage is a substantial factor in the global carbon cycle. Carbon sequestration in agricultural soils, and the assessment and validation of soil carbon storage, are crucial for the mitigation of agricultural greenhouse gas emissions and for steering towards sustainable farming practices. Enforcement and verification of carbon sequestration policies, methods, and models require extensive soil carbon monitoring capability. However, current conventional laboratory-based methods for soil carbon estimation are laborious, expensive, and time-consuming. In this work, we have developed a compact, robust, and field-capable experimental device based on laser-induced breakdown spectroscopy (LIBS) for the rapid assessment of total soil carbon content and its spatial distribution in mineral soils. The carbon content quantification was performed using a spectral line of carbon at a wavelength of 193.1 nm emitted from the laser-induced plasma plume. The LIBS measurements were performed on soil samples collected from 28 different locations and various depths (up to 1 m) of a test field cultivated with a forage legume (red clover - Trifolium pratense, L.) and grass (Timothy - Phleum pratense, L.) mixture in eastern Finland. A calibration model was established based on a limited and randomly chosen sample set and validated by comparing soil carbon estimates obtained from various locations in the test field using the dry combustion (LECO) method. Further, we demonstrate here the usefulness of LIBS methodology for mapping three-dimensional carbon distribution at the test field. We emphasize here that the calibration model can be generalized to other sample areas under similar soil type with a relative error of less than 10 % and possesses potential for fast on-site determination of spatial variation in total soil carbon, reducing substantially the need of time-consuming sample processing in laboratory. Therefore, LIBS enables frequent and extensive spatial and temporal soil carbon mapping and has the potential to become part of the future carbon monitoring network.
KW - LIBS
KW - Quantification
KW - Soil analysis
KW - Spatial variation
KW - Total soil carbon
U2 - 10.1016/j.geoderma.2023.116550
DO - 10.1016/j.geoderma.2023.116550
M3 - Article
AN - SCOPUS:85162904180
SN - 0016-7061
VL - 436
JO - GEODERMA
JF - GEODERMA
M1 - 116550
ER -