Refining Total Oxygen Content in the Solid Soil Phase

Resumo

Presenting data on the total chemical analysis in the form of oxides is characterized by significant drawbacks: this conditional form does not correspond to the actual content of soil minerals. The oxide form distorts the real ratio between the content of different elements in soil. It is obvious that the total chemical composition should be expressed in the form of elements, including oxygen as an element with the maximal clarke. It is necessary to take into consideration the correction for oxygen loss at soil ignition. With respect to this, the studied soils may be divided into three groups. Oxygen content in podzols of the Russian Plain increases slightly after the correction, and the total chemical composition practically remains unchanged. For vertisols of Southern Siberia, oxygen content increases by 3–4% after the correction. The neglect of this fact results in a significant error in the content of some elements: K, Al, Fe, and especially Ti. For oxisol of Norfolk Island characterized by a high participation of ignition-unstable gibbsite, oxygen content increases by 7–8% after the correction. This causes a noticeable error in the contents of O, Al, Fe, and especially Ti. Thus, oxisols require the correction for oxygen.