The combination of plastic film mulching and subsurface organic
amendment is a novel strategy for saline soil amelioration and
utilization in China. However, how the strategy affect soil organic
carbon (SOC) contents directly and indirectly (physical protection and
microbiological regulation) were still not-documented. Therefore, four
treatments, i.e., no amendment with and without plastic film mulching,
subsurface (10-30 cm soil depth) organic amendment with and without
plastic film mulching, were arranged and sampled after three-year filed
experiment. Compared with no amendment with and without plastic film
mulching, subsurface organic amendment increased the SOC content in the
0-40 cm soil depth by 70% and 90%, respectively. Plastic film mulching
decreased SOC by 16% without organic amendment. Subsurface organic
amendment transformed the dominant aggregation particles from
<0.053 mm to 0.25-2 mm, indicating that both direct carbon
input and indirect physical protection contributed to SOC increment.
Conversely, SOC decreased with plastic film mulching due to the 14%
lower fungal diversity compared with soil without plastic film mulching,
was supported by the positive path coefficient from fungal diversity to
SOC. Therefore, the combination of plastic film mulching and subsurface
organic amendment increased SOC by 61% by direct carbon input and
indirect physical protection and microbial regulation. In conclusion,
subsurface organic amendment with plastic film mulching reinforced soil
organic carbon increment through altering saline soil aggregate
structure and regulating fungal community, and confirmed it is a
feasible way to increase SOC for saline soil amelioration.
The microbially mediated soil organic carbon loss under degenerative succession in an alpine meadow