水保所知识产出(1956---)知识库

Soil erosion has important influence on soil processes and particularly soil nutrient dynamics, which in turn
affects the terrestrial C and N cycling and greenhouse gases emission. However, the responses of carbon (C) and
nitrogen (N) cycling in soils and soil fractions to erosion remain largely unclear, hindering the precise prediction
of the fate of C and N in the terrestrial ecosystem. Herein, we compared the mineralization of organic carbon
(OC) and N at two different temperatures (15 and 25 ◦ C) in bulk soils and aggregate fractions of 19 soils before
and after a simulated rainstorm. The temperature sensitivity (Q 10 ) of OC and N mineralization was calculated.
Soil samples were collected from 9 sites across China, with soil types of Alfisols, Inceptisols, Mollisols, Ultisols,
and land uses of croplands, grasslands, and woodlands. The soil aggregate fractions were >2, 2-1, 1-0.25 and
<0.25 mm, respectively. We hypothesized that erosion will decrease OC and N mineralization due to the loss of
labile organic matter from soils and that the effects of erosion would decrease with clay content and vary with
different aggregate fractions. In support of these hypotheses, the cumulative mineralized OC and N (C m and N m )
in the soils and aggregate fractions were decreased of 78-85% and 37-52% after erosion, and the temperature
sensitivities of OC and N mineralization were decreased of 80-84% and 4-43%, respectively. The effects of
erosion varied with site where the soil was collected. The decreases in C m and N m mainly occurred in small
aggregate sizes (1-0.25 and <0.25 mm fractions). The C m and N m in bulk soils and aggregates increased
significantly with the contents of OC, N, labile OC and mineral N but were texture independent. These results
highlighted significantly reduction of OC and N mineralization at eroding sites, which should be carefully
considered when assessing emissions of greenhouse gases in eroding environments.