TYURINS METHOD AND OTHER METHODS USED IN UNDERSTANDING HUMIFICATION AND AGGREGATE FORMATION

This study first gives an overview of the nature of the components whi ch comprise soil organic matter. Tyurin's method of humus fractionatio n is then compared to other methods which radically break down aggrega tes (Bruckert and Gaiffe method). The results of this comparison provi de useful information as to the role of three cations (calcium, iron, and aluminum) in humification. Two experiments conducted by one of the authors show the importance of soluble calcium in the formation of bo th microaggregates and macroaggregates. The authors investigate the ac tion of iron and aluminum hydroxide, the makeup of the various humic c ompound forms, and the biomolecules which act as the ''cement'' in bin ding both microaggregates and macroaggregates. Conclusions are drawn a s to the three processes involved in humification, structuring and ped ogenesis which are conditioned both by the climate and cations freed b y weathering. The main processes are further defined: podzolization, b runification, andosolization, calcic and climatic melanization.