3.3 Microstructures of soil aggregates
A significant difference was observed in the two-dimensional shape between the splashed soil aggregates and the undisturbed soil (Figure 2D). The undisturbed soil aggregates primarily consisted of macroaggregates with clear outlines and boundaries, containing more macropores and a relatively loose soil structure (Figure 2A). Compared with the undisturbed soil, the soil structure after raindrop splashing was more compact, the number of macropores was reduced, the number of small and medium aggregates was increased, and the phenomenon of fragmentation was shown. Markedly, after being splashed by rainfall at the intensity of 217.26 mm h-1, the soil aggregates were the most broken (Figure 2B-D). The 3D structural differences of soil aggregates were more obvious than those in 2D (Figure 2 and 3D). After splashing, the percentage of soil macroaggregates was reduced, being replaced by an increased number of microaggregates; this result indicates that the aggregates were obviously broken, and the soil structure was relatively denser. Table 3 reports that the average aggregate particle size in splashed soil was significantly smaller than that of the undisturbed soil (P < 0.05), especially after a rainfall intensity of 68.61 and 217.26 mm h-1. The average aggregate particle size decreased by 2.43%, 3.25% and 3.55% after splashed by three rainfall intensities, respectively. This result is consistent with the micromorphology of aggregates.