Comparison of 0.1N sodium hydroxide with 0.1M sodium pyrophosphate in the extraction of soil organic matter from various soil horizons

• Published in: Communications in soil science and plant analysis Vol. 28; no. 13-14; pp. 1141 - 1150
• Main Authors: Michaelson, G. J., Ping, C. L.
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.07.1997; Taylor & Francis
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Geochemistry; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil and rock geochemistry; Soil science; Analytical chemistry; Soil chemistry; Laboratory study; Extraction agent; Organic matter; Sodium Diphosphates; Extraction process; Sodium hydroxide; Analysis method; Soil horizons; Soil science; Histosols; Inceptisols; Comparative study; Spodosols; Method study
• ISSN: 0010-3624; 1532-2416
• DOI: 10.1080/00103629709369861

Soil samples representing the O, A, B, and C soil horizons from soil organic matter (SOM) studies were selected to study the relative effectiveness of 0.1N sodium hydroxide (NaOH) and 0.1M sodium pyrophosphate (NaPyr) in extracting organic carbon (OC). Replicate samples were extracted with each extractant in a ratio of about 1:144 and successive extractions were performed for each soil. Results indicated the importance of successive extractions for more complete removal of extractable OC. A single extraction removed an average of only 68%, 78%, 86%, and 60% of the OC extracted with four successive extractions for the O, A, B, and C horizons, respectively. The C horizons were lowest in OC and the slowest to release OC in the extraction process. Organic C was solubilized from the B horizons most quickly with an average of 95% of the successively extractable OC removed with only two extractions. The extractability of the soil TOC was highest in the Bhs and then the Bw, C, A, and O horizons at 92% and 42%, 46%, 38%, and 3 6%, respectively. The NaOH and NaPyr were nearly equal in extracting OC from the Bhs horizons. The NaOH extracted more OC than the NaPyr at 53%, 55%, 29%, and 47% more in the O, A, Bw, and C horizon samples, respectively. These results stress the importance of considering the soil horizon type and the use of NaOH in successive extraction for maximum removal of OC in soil studies.