A THERMOGRAVIMETRIC STUDY OF ORGANIC MATTER OF REPRESENTATIVE CANADIAN PODZOL SOILS

Abstract

Differential thermogravimetric (DTG) curves of untreated peat, muck, and 10 different Podzol L–H materials showed peaks at approximately 100 °C (moisture), 280° (low-temperature band), and 370 to 390 °C (high-temperature band). The maxima at 280 °C were sharp and characteristic of all surface materials investigated. The DTG curves were essentially the same for all of the Podzol L–H materials investigated.The DTG curves for 12 organic matter preparations extracted from Podzol Bh, Bfh, Bhf, Bfl, and Btf horizons showed maxima at 100 °C and in the 420 to 520 °C region (high-temperature band). The peaks at 280 °C were virtually absent in these materials. This suggested differences in composition between L–H and B horizon organic matter of the Podzols studied. The variations in the positions of the high-temperature bands of the B materials were related to the morphological characteristics of these soils in the field. From this it appeared that thermogravimetry might be a useful aid in soil classification.Addition of inorganic materials did not affect the position of the low-temperature bands but had a pronounced effect on the high-temperature bands of both L–H and B organic matter. Addition of Na caused the peaks of the latter to shift to higher temperatures while addition of Al and Fe caused shifts to lower temperatures.