Is the Walkley–Black Method Suitable for Organic Carbon Determination in Chilean Volcanic Soils?

Matus, Francisco; Escudey, Mauricio; Förster, Juan E.; Gutiérrez, Marlen; Chang, Andrew C.

doi:10.1080/00103620902896746

Cited by 22 publications

(12 citation statements)

References 14 publications

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“…The mean SOC content (37.3 g kg −1 soil) of the 45 soil samples used for dry combustion was similar ( p > 0.25) to the mean of the 53 soil samples used for wet oxidation (41.4 g kg −1 soil). This absence of any difference shows that wet digestion recovered > 95% of the C estimated by dry combustion in Mediterranean 75 and volcanic soils 76 . (3) There were no significant differences observed in the C-silt + clay contents between samples treated with low ultrasonic energy (< 29 kJ) (e.g., Schmidt et al 54 ) and those treated using high energy (> 75 kJ) (e.g., Yang et al 33 ; Tiessen and Steward 52 ).…”

Section: Resultsmentioning

confidence: 93%

Fine silt and clay content is the main factor defining maximal C and N accumulations in soils: a meta-analysis

Matus

2021

Sci Rep

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When studying carbon (C) sequestration in soil, it is necessary to recognize the maximal storage potential and the main influencing factors, including the climate, land use, and soil properties. Here, we hypothesized that the silt and clay contents in soils as well as the clay mineralogy are the main factors affecting the maximal C and N storage levels of soils. This hypothesis was evaluated using a database containing the organic C contents of topsoils separated by ultrasonic dispersion to determine the particle size fractions. The slopes of the linear regressions between the C contents in silt and clay to the soil organic C (SOC) and between the N contents in silt and clay to the total N content were independent of the clay mineralogy (2:1, 1:1, calcareous soil, amorphous clays), climate type (tropical, temperate, and Mediterranean), and land use type (cropland, grassland, and forest). This clearly shows that the silt and clay content is the main factor defining an upper SOC level, which allowed us to propose a generalized linear regression (R2 > 0.95) model with a common slope, independent of the land use and climate type, to estimate the soil C sequestration potential. The implications of these findings are as follows: (1) a common slope regression was accurately calculated (0.83 ± 0.02 for C-silt + clay < 63 μm and 0.81 ± 0.02 for C-silt + clay < 20 μm) and (2) there was no asymptotic pattern found to support the existence of an SOC saturation pool.

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Section: Resultsmentioning

confidence: 93%

Fine silt and clay content is the main factor defining maximal C and N accumulations in soils: a meta-analysis

Matus

2021

Sci Rep

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“…The total organic carbon was determined by the Walkley-Black method (Kakad and Thakare 2017; Matus et al 2009). About 5g of the dried soil and food crop samples were grounded to pass through a 0.5 mm sieve.…”

Section: Determination Of Total Organic Carbonmentioning

confidence: 99%

Concentration Assessment And Source Evaluation of Polycyclic Aromatic Hydrocarbons (PAHs) In Soil And Crops of The Agro-Industrial Tobacco Production Area of Igboho, Nigeria

Adedosu

Ajibade

Omotayo

et al. 2021

Preprint

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The contribution of tobacco smoking and cigarette butts to global environmental pollution has been given significant attention. However, little is known about tobacco-related agricultural activities on environmental pollution by polycyclic aromatic hydrocarbons (PAHs). In this study, the spatial distributions, composition, source, and toxicity potential of polycyclic aromatic hydrocarbons (PAHs) in soil and food crops within the vicinity of the agro-industrial tobacco production area of Igboho, Nigeria was investigated. Soil and food crop (Zea mays, Dioscorea alata, and Manihot esculenta) samples collected from the tobacco curing site and the surrounded farmlands were analyzed for the PAHs concentrations. The identification and quantification of priority PAHs in the samples were carried out using a gas chromatograph equipped with a flame-ionization detector. The total concentration of the priority PAHs in the soil ranged between 136.70 ng.g-1 to 889.30 ng.g-1. The total concentration of carcinogenic PAHs ranged from 6.07 ng.g-1 to 321.04 ng.g-1, and the total concentration of toxic PAHs ranged from 6.27 ng.g-1 to 254.37 ng.g-1. The PAHs level was highest in crops from farmlands closest to the tobacco curing site. The distribution of PAHs ring size is in the order of 6-rings ˃ 4-rings ˃5-rings ˃ 3-rings ˃ 2, and the diagnostic indices showed that the sources of PAHs in the samples were mainly pyrogenic and associated with tobacco curing activities in the area.

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“…Soil organic carbon (SOC) analysis by the Walkley-Black (WB) method (Walkley & Black, 1934) has been in use since its development (Matus et al, 2009). Limitations to this method are incomplete oxidation and underestimation of SOC.…”

Section: Introductionmentioning

confidence: 99%

“…Soil organic carbon (SOC) analysis by the Walkley‐Black (WB) method (Walkley & Black, 1934) has been in use since its development (Matus et al. , 2009).…”

Section: Introductionmentioning

confidence: 99%

Optical sensing and chemometric analysis of soil organic carbon – a cost effective alternative to conventional laboratory methods?

Rourke

Holden

2011

Soil Use and Management

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Soil organic carbon (SOC) is frequently determined by the Walkley‐Black (WB) method. A limitation of the test is incomplete oxidation of the carbon fraction and underestimation of SOC. Automated dry combustion methods are expensive and slow. Optical sensing and chemometric analysis offer the potential of an economical method capable of quantifying SOC fractions. The aim of this study was to identify the best SOC analysis method to facilitate maximum sampling resolution based on the cost per sample, analytical accuracy and time. A comparative evaluation was made of five techniques; (1) the WB method, (2) total combustion by total organic C analyser, (3) infrared (IR) diffuse reflectance spectroscopy, (4) a portable spectroradiometer and (5) laboratory hyperspectral imaging. This involved assessing equipment costs, consumables and time to derive total analytical cost. The benefits were sample throughput and analytical accuracy. Instrumentation represented the largest input to analytical cost and for optical methods was governed by the spectral range. In contrast to dry combustion, this cost is offset by high sample throughput and minimal consumable requirements for IR spectroscopy and hyperspectral imaging. Hyperspectral imaging is identified as the most rapid technique with potential to scan about 720 samples per day at 90% less cost than the WB method. The opportunity cost of hyperspectral imaging is to forfeit some analytical accuracy associated with the dry combustion method. Dry combustion, despite its high cost per sample, incurs no further costs associated with updating prediction models or developing site or soil specific correction factors.

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Is the Walkley–Black Method Suitable for Organic Carbon Determination in Chilean Volcanic Soils?

Cited by 22 publications

References 14 publications

Fine silt and clay content is the main factor defining maximal C and N accumulations in soils: a meta-analysis

Fine silt and clay content is the main factor defining maximal C and N accumulations in soils: a meta-analysis

Concentration Assessment And Source Evaluation of Polycyclic Aromatic Hydrocarbons (PAHs) In Soil And Crops of The Agro-Industrial Tobacco Production Area of Igboho, Nigeria

Optical sensing and chemometric analysis of soil organic carbon – a cost effective alternative to conventional laboratory methods?

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