Establishing a standard protocol for soil texture analysis using the laser diffraction technique

Stacanelli Pires Scott, Isis and Nouwakpo, S.K. and Bjorneberg, D.L. and Rogers, C.W. and Vitko, L. F. (2024) Establishing a standard protocol for soil texture analysis using the laser diffraction technique. Soil Science Society of America Journal. 3 August 2024. pp. 1-18.

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Abstract

Optical methods including laser diffraction have been increasingly used to measure soil texture and particle size distribution. However, they have not been adopted yet as a routine methodology mainly due to the difficulties in comparing their results to more commonly-used techniques (i.e., sedimentation methods). Many attempts exist in the literature to find an agreement between methodologies with relative success. In this work, we aim to improve the agreement between methodologies by adjusting parameters of the laser diffraction analysis, including sample treatment (chemical dispersion, carbonate removal, sand separation), mode of sample addition (sub-sampling versus transmittance matching), and analysis parameters (time of sonication, refractive index). Soil texture class determined by laser diffraction agreed with the sieve-hydrometer method in 98% of the runs when the following parameters were used: (1) Refractive index of 1.44 - 0.100i, (2) 180 seconds of sonication, (3) sand sieving prior to analysis, and (4) sample dispersion by shaking the sample for 1 hour with 5% of sodium hexametaphosphate. We observed that adding the entire sample to the analyzer (1 g of soil in 100 mL of dispersant) while keeping the appropriate levels of transmittance through dilution (transmittance matching) is a better way of sample addition in comparison to sub-sampling, especially for coarser soil samples. This work proposes a standard operation procedure that may broaden the adoption of laser diffraction analysis as a routine soil texture methodology.

Item Type:	Article
NWISRL Publication Number:	1793
Subjects:	Soil
Depositing User:	Users 11 not found.
Date Deposited:	23 Aug 2024 20:12
Last Modified:	23 Aug 2024 20:12
Item ID:	1836
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1836