Soil structure refers to the spatial arrangement of primary soil particles and pores, and is known to influence a
variety of soil functions including carbon sequestration and water holding capacity. At present, research in this
field is often divided, focusing either on pores where pore networks are investigated in undisturbed soil or on
solids where isolated soil aggregates are commonly studied. The choice of approach depends on the needs and
traditions in different disciplines of soil science. While there is much debate regarding how well these viewpoints
relate to each other, there have been only marginal research efforts undertaken to compare them quantitatively.
In this study, we presented and evaluated methods to identify 3-D subunits in X-ray images of eight undisturbed
soil samples that we interpreted as macroaggregates, and compared these to to results from drop-shatter tests.
Here, we exploited the cohesive forces of water that induces shrinkage cracks under drying. Despite promising
trends, comparisons between image and drop-shatter test derived aggregate properties remained inconclusive.
Nevertheless, our results encourage further investigations on larger sample sets and different observation scales.
The here presented and discussed aggregate delineation methods illustrate an approach to harmonize soil
structure characterization in terms of both pore-networks and soil aggregation. For example, respective extended
approaches may be developed to evaluate the locations of microaggregates within macroaggregates.