Response of soil aggregate disintegration to the different content of
organic carbon and its fractions during splash erosion
Aggregate disintegration is a critical process in soil splash erosion.
However, the effect of soil organic carbon (SOC) and its fractions on
soil aggregates disintegration is still not clear. In this study, five
soils with similar physical and chemical properties and different
contents of SOC have been used. The effects of slaking and mechanical
striking on splash erosion were distinguished by using deionized water
and 95% ethanol as raindrops. The simulated rainfall experiments were
carried out in four heights (0.5, 1.0, 1.5, and 2.0 m). The result
indicated that the soil aggregate stability increased with the increases
of SOC and light fraction organic carbon (LFOC). The relative slaking
and the mechanical striking index increased with the decreases of SOC
and LFOC. The reduction of macroaggregates in eroded soil gradually
decreased with the increase of SOC and LFOC, especially in alcohol test.
The amount of macroaggregates (>0.25mm) in deionized water
tests were significantly less than that in alcohol tests under the same
rainfall heights. The contribution of slaking to splash erosion
increased with the decrease of heavy fractions organic carbon (HFOC).
The contribution of mechanical striking was dominant when the rainfall
kinetic energy increased to a range of threshold between 9 J m-2 mm-1
and 12 m-2 mm-1. This study could provide the scientific basis for
deeply understanding the mechanism of soil aggregates disintegration and