EFFECTS OF NaOH CONCENTRATION ON THE EXTRACTION OF ORGANIC MATTER AND OF MAJOR INORGANIC CONSTITUENTS FROM A SOIL

Abstract

Soil samples taken from a Podzol Bh horizon were extracted with NaOH solutions, ranging in concentrations from 0.05 to 1.0 N. The highest proportions of soil C, N, Al2O3, Fe2O3, SiO2 K2O, and P2O5 were extracted by 0.1 and 0.15 N NaOH solutions.Following extraction, aliquots of each extract were passed over H-resin. The ash contents of purified extracts were as follows: 0.05 N NaOH = 27%; 0.1 N NaOH = 17%; 0.15 N NaOH = 13%; 0.25 N NaOH = 7%; 0.35 N NaOH and higher = < 5%. Repeated passage over H-resin of organic matter extracted by low base concentrations did not substantially lower the ash content. The most suitable extractant for obtaining organic matter preparations low in ash content was 0.4 or 0.5 N NaOH solution.