Comparison of Zimmermann and Six Fractionation Methods Aimed at Distinguishing Between Active, Slow, and Passive Pools of Soil Organic Matter
Abstract
Recently, soil organic matter (SOM) fractionation has become an important tool to separate SOM pools with different stability and decomposability. Several methods have been developed for this purpose.
Here, we used laboratory experiments manipulating two types of post-mining soils in the early stages of soil development to compare two fractionation methods according to Zimmermann and Six. Overall, both fractionation methods showed good agreement.
In the active pool, Six's method tended to show systematically higher values than Zimmermann's; the opposite was true for the passive and slow pools, but the difference between fractionation methods was less pronounced here. Moreover, among all treatments, clayey soil resulted in a higher active pool in the Six's method, in contrast to a higher slow pool in Zimmermann's fractionation method.
In the passive pool, Six's method tended to be higher in sandy soil, while there was no clear trend in clayey soil. This implies that soil texture plays an important role in variation between methods.
The ANOVA further revealed that fractionation methods, treatments, and their interactions had a significant effect on all the SOC pools.