Data for: Methodological choices in size and density fractionation of soil carbon reserves – A case study on wood fiber sludge amended soils

A myriad of methods is currently being applied in soil carbon research encompassing major variation in the basic principles and minor variation in details. The most proper method is dependent on the research question and soil type, wherefore a consensus will likely never be reached, and it is difficult to label any method inappropriate. Both the fundamental and the subtle choices in methodology affect the results, wherefore increasing the method-related understanding of soil, agricultural and environmental scientists is of utmost importance. In scientific literature, methods are often not thoroughly presented, let alone reasoned. With this data, we discuss methodological choices in soil carbon fractionation. In addition, our case study follows the effects of pulp mill sludge amendments on soil carbon in a Luvic Stagnosol and Dystric Arenosol. Organic materials are being applied to soil to increase productivity and soil carbon storage. Our results show the difficulties of accumulating carbon in the stable, mineral associated pool, when the carbon content is initially relatively high, and the sorption capacity of the mineral phase already largely occupied.