5 CONCLUSIONS
This study found that the number of aggregates increased as the rainfall
intensity increased, especially for the rainfall intensities of 68.61
and 217.26 mm h-1 (P < 0.05). The
distribution of aggregate particles was affected by the original soil
distribution and rainfall intensity, which decreased the number of
500-1000 μm aggregate particles and increased the number of <
500μm aggregate particles. The fractal dimension (FD) and specific
surface area (SSA) increased significantly after raindrop splash
(P < 0.05); as rainfall intensity increased, the FD and
SSA values also increased. A greater degree of fragmentation led to a
higher proportion of fine particles in the soil and more unstable soil
aggregates. After raindrop splashing, especially from an intensity of
68.61 and 217.26 mm h-1, the microstructure of
aggregates was denser than the undisturbed soil, and the average
particle diameter of the aggregate decreased by 2.43%, 3.25% and
3.55%, respectively, compared with the undisturbed soil.
Aggregate breakdown was mainly caused by moderate to great rainfall
intensities. The degree of fragmentation increased with the increase of
raindrop diameter, rainfall intensity and rainfall energy, and more
aggregate particles converted to finer particles. Consequently, these
tiny particles intensified the pore clogging and infiltration weakening,
exacerbated surface runoff and soil loss and reduced soil fertility;
this process even accelerated the formation of surface crust and
destroyed the soil structure. Therefore, to improve our understanding of
the soil erosion process, synchrotron-based X-ray microcomputed
tomography should be more widely used in the field of soil erosion, in
combination with other methods, to study microstructure and soil
aggregate fragmentation mechanisms.
CONFLICT OF INTEREST
There is no conflict of interest to declare.
ORCID
Li Guangluhttps://orcid.org/0000-0003-4107-8587