Results of an Interdisciplinary Research Project on Soil Aggregate Formation in CZO's

Samenvatting

Soil physical properties such as aggregate stability and porosity are crucial for the soil’s agricultural productivy, carbon sequestration capacity and water holding capacity. The formation of soil aggregates is the result of complex interactions between biological, chemical and physical soil processes. Therefore, multi-disciplinary research on Critical Zone Observatories (CZO’s) is needed to unravel the keyfactors controlling aggregate formation [1]. We will discuss the role of soil chemical and biological processes in the formation of soil aggregates. These data are the result of the joined efforts from soil chemists and biologist collaborating within the SoilTrEC project [2]. We show that organic-mineral interactions and solution chemistry are important for formation of primary soil aggregates. Especially Fe-(hydr)oxides play a crucial role because of their strong interactions with organic substances in the soil [3]. Macroaggregates are formed when both organic matter, clay minerals and Fe-(hydr)oxides are present in sufficient amounts. These soil macro-aggregates act as habitats for micro-organisms which may in turn alter the organic substances within the soil aggregates. The microbial communitities within the macro-aggregates are affected by the land use. Furthermore, land use shows pronounced effects on the structure of the pores within the soil macro-aggregates. Overall, we want to highlight the importance of multidisciplinary research in understanding the complex interactions between chemical and biological processes within the critical zone.