Sample processing impacts on single wet sieve aggregate stability analysis

Garcia, Glenn Arthur A.; Warren, Jason G.; Abit, Sergio M.; Garcia, Chime; Ogden, Grace Flusche

doi:10.1002/ael2.20094

Cited by 2 publications

(2 citation statements)

References 30 publications

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“…3 & 4; Supplemental Tables S5 & S7). Mechanical grinders are commonly used to sieve and grind soils at commercial labs (Garcia et al, 2022) because they significantly accelerate soil processing time, reducing total costs of analyses (Supplemental Fig. S8).…”

Section: Sievingmentioning

confidence: 99%

“…Most soil processing methods include a step to sieve air-dried bulk soil and commercial service soil testing labs often utilize a mechanical flail or disk grinder (Garcia et al, 2022) to increase throughput over hand sieving. Based on a survey of 51 soil testing labs, we found that over 70 % use some type of mechanical grinder to sieve (Supplementary Table S1).…”

Section: Introductionmentioning

confidence: 99%

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Large errors in common soil carbon measurements due to sample processing

Even,

Machmuller,

Lavallee

et al. 2024

Preprint

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Abstract. To build confidence in the efficacy of soil carbon (C) crediting programs, precise quantification of soil organic carbon C (SOC) is critical. Detecting a true change in SOC after a management shift has occurred, specifically in agricultural lands, is difficult as it requires robust soil sampling and soil processing procedures. Informative and meaningful comparisons across spatial and temporal time scales can only be made with reliable soil C measurements and estimates, which begin on the ground and in soil testing facilities. To gauge soil C measurement inter-variability, we conducted a blind external service laboratory comparison across eight laboratories selected based on status and involvement in SOC quantification for C markets. To better understand how soil processing procedures and quantification methods commonly used in soil testing laboratories affect soil C concentration measurements, we designed an internal experiment assessing the individual effect of several alternative procedures (i.e., sieving, fine grinding, and drying) and quantification methods on total (TC), inorganic (SIC), and organic (SOC) soil C concentration estimates. We analyzed 12 different agricultural soils using 11 procedures that varied either in the sieving, fine grinding, drying, or quantification step. We found that a mechanical grinder, the most commonly used method for sieving in service laboratories, did not effectively remove coarse materials (i.e., roots and rocks), thus resulted in higher variability and significantly different C concentration measurements from the other sieving procedures (i.e., 8 + 2 mm, 4 mm, and 2 mm with rolling pin). A finer grind generally resulted in a lower coefficient of variance where the finest grind to < 125 µm had the lowest coefficient of variance, followed by the < 250 µm grind, and lastly the < 2000 µm grind. Not drying soils in an oven (at 105 °C) prior to elemental analysis on average resulted in a relative difference of 3.5 % lower TC, and 5 % lower SOC due to inadequate removal of moisture. Compared to the reference method used in our study where % TC was quantified by dry combustion on an elemental analyzer, % SIC was measured using a pressure transducer, and % SOC was calculated by the difference of % TC and % SIC, predictions of all three soil properties (% TC, % SIC, % SOC) using Fourier Transformed Infrared Spectroscopy were in high agreement (R2 = 0.97, 0.99, 0.90, respectively). For % SOC, quantification by loss on ignition had a low coefficient of variance (5.42 ± 3.06 %) but the least agreement (R2 = 0.83) with the reference method.

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Section: Sievingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Large errors in common soil carbon measurements due to sample processing

Even,

Machmuller,

Lavallee

et al. 2024

Preprint

View full text Add to dashboard Cite

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A practical, reproducible laboratory method for assessing soil aggregate stability

Monteith,

Seybold,

Nelson

2024

Agrosystems Geosci & Env

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Soil aggregate stability is an important soil physical measurement that is closely related to a range of soil health functions. It is defined by its analytical method and often within‐method variability and inter‐method comparability have not been addressed and quantified. The current Natural Resources Conservation Service Kellogg Soil Survey Laboratory (KSSL) method for analyzing aggregate stability uses non‐standardized equipment and hand‐sieving techniques and is not easily scalable. The objective of this study was to evaluate and modify an alternative method that uses a single sieve mechanical wet sieving apparatus (MWS method) to produce results comparable to the current KSSL method and evaluate another alternative method that uses multiple sieves in a custom‐fabricated Yoder‐type apparatus. The two methods were evaluated for efficiency, repeatability, and scalability. The MWS method uses standardized equipment and methods, which should be scalable and reproducible in different laboratories. Sample preparation, pretreatment, and sieving parameters of the MWS method were adjusted to produce analytical results which most closely matched the KSSL method. Repeated analysis of soil sample standards showed that within‐method variability of the MWS method was slightly less than in the KSSL method. In a comparison of 90 samples of widely varying properties, Lin's concordance correlation coefficient was 0.927, indicating a moderate strength of agreement between the MWS method and KSSL method. Results from a modified Yoder method were not comparable to the KSSL method, and the greater time requirements, procedural complexity, and large equipment footprint were identified as practical limitations for use in large‐scale laboratory applications.

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Sample processing impacts on single wet sieve aggregate stability analysis

Cited by 2 publications

References 30 publications

Large errors in common soil carbon measurements due to sample processing

Large errors in common soil carbon measurements due to sample processing

A practical, reproducible laboratory method for assessing soil aggregate stability

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