ALKALI VERSUS ACID EXTRACTION OF SOIL ORGANIC MATTER

Abstract

INFORMATION IN THE LITERATURE SUGGESTS THAT ALKALI EXTRACTION MODIFIES SOIL ORGANIC MATTER. TO UNCOVER SUCH EFFECTS, SOIL SAMPLES TAKEN FROM A PODZOL BH HORIZON WERE EXTRACTED AT ROOM TEMPERATURE WITH 0.5 N NAOH UNDER N SUBSCRIPT 2 AND WITH 0.1 N HCL. FOLLOWING PURIFICATION, EACH EXTRACT WAS CHARACTERIZED BY ULTIMATE AND FUNCTIONAL GROUP ANALYSIS, BY INFRARED SPECTROSCOPY AND BY GEL FILTRATION ON SEPHADEX G-50 G-25. THE EXPERIMENTAL DATA SHOWED THAT THE CHARACTERISTICS OF THE TWO EXTRACTS WERE PRACTICALLY IDENTICAL, AND THAT ALKALI EXTRACTION HAD EITHER CAUSED NO MODIFICATIONS OR, AT MOST, ONLY VERY SLIGHT ONES IN THE ORGANIC MATTER INVESTIGATED. IT IS LIKELY THAT DAMAGING EFFECTS ASCRIBED IN THE LITERATURE TO ALKALI EXTRACTION HAVE BEEN EXAGGERATED, ESPECIALLY AS THESE APPLY TO SOIL HUMIC COMPOUNDS. /AUTHOR/