Abstract
Soil samples from T (0~20 cm) and S (20~40 cm) layers of four saline–alkali rice fields (R5, R15, R20, and R35) with different reclamation years were selected to study the distribution of soil aggregates and the contents of readily oxidizable organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), potentially mineralizable carbon (PMC), and soil organic carbon (SOC). The effects of large macroaggregate (>2 mm, LMA), small macroaggregate (0.25 to 2 mm, SMA), and microaggregate (<0.25 mm, MA) particle size, soil layer, and soil physicochemical properties on SOC fractions were also analyzed. The results showed that the LMA size in saline–alkali paddy fields were easily decomposed and was unstable due to the influence of the external environment. With the increase in reclamation years, the proportion of LMA in the S layer decreased gradually. The ROC, DOC, MBC and TOC contents of aggregates in the T and S layers gradually increased with the increase in reclamation years, and SOC fractions contents of aggregates in different grain sizes were SMA > LMA > MA. An effective way to increase carbon sink and improve the ecological environment in western Jilin Province is to change the soil environment by planting rice in saline–alkali land.
Highlights
Soil aggregates are the material basis for the formation of good soil structure [1].Different particle size aggregates determine the distribution of soil pores, morphological characteristics, and soil sensitivity to external stress [2,3,4]
The research on soil organic carbon (SOC) of aggregates mainly focuses on content and distribution, and there are few studies on SOC fractions such as readily oxidizable organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), and potentially mineralizable carbon (PMC) in aggregates of different grain sizes in saline-alkali paddy fields
We found that the distribution of LMA was higher than that of SMA and MA, which
Summary
Soil aggregates are the material basis for the formation of good soil structure [1].Different particle size aggregates determine the distribution of soil pores, morphological characteristics, and soil sensitivity to external stress [2,3,4]. Soil aggregates are the material basis for the formation of good soil structure [1]. As the main cementitious material, soil organic carbon (SOC) affects the formation of soil aggregates, which act as carriers to regulate the storage and turnover of SOC. In the process of aggregate formation, SOC is wrapped in its interior, and its special structure is not conducive to the decomposition and utilization of organic carbon by microorganisms, effectively protecting SOC. The research on SOC of aggregates mainly focuses on content and distribution, and there are few studies on SOC fractions such as readily oxidizable organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), and potentially mineralizable carbon (PMC) in aggregates of different grain sizes in saline-alkali paddy fields.
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