Temporal variation in soil carbon in various paddy soil types in a cold temperate continental monsoon climate

Abstract

Soil organic carbon (SOC) is the most important carbon pool in the terrestrial ecosystem. However, temporal variations in paddy SOC under a temperate continental monsoon climate are poorly understood. Here, we demonstrate that significant SOC variations occur in meadow soil (MS), black soil (BS) and planosol (PS) paddy soils. Several soil samples were collected from different regions where rice was cultivated for 1, 6, 10, 23 and 40 years for MS samples; for 1, 6, 10, 20 and 35 years for BS samples and 1, 5, 10, 15 and 25 years for PS samples. The total organic carbon (TOC) content and humus organic carbon (HOC) content were found to increase as the rice cultivation duration increased, while the mineralizable organic carbon (MOC) content and carbohydrate organic carbon (COC) content exhibited the opposite trend. The relationships between the relative carbon accumulation (Y) in the three soil types and time (X) were consistent with the following models: Y TOC = 0.9973X 0.0245 , Y HOC = 0.9936X 0.0457 , Y MOC = 1.023X −0.073 , and Y COC = 1.040X −0.059 , describing the temporal variation in the various forms of organic carbon in paddy soils under a temperate continental monsoon climate.The results of this study provide a reference for soil carbon pool management and fertilization management.

Impacts of farming activities on carbon deposition based on fine soil subtype classification

“…Most of the carbon sinks in the terrestrial natural environment are stored in the soil (Tao et al, 2023) and a large deposition of SOC reduces the concentration of CO 2 in the atmosphere (Xiao et al, 2023). Due to human farming activities impacting carbon sequestration, soil carbon sinks have been altered (Wang et al, 2022). There is an equilibrium relationship in the carbon cycle in the natural state and human activities undoubtedly affect this balance (Ren et al, 2023).…”

“…The 90 soil samples described above were sent to the laboratory to measure TOC, HOC, COC and MOC according to a previously listed methods (Wang et al, 2022). Briefly, these four organic carbon measurement methods were used in order: oil-bath potassium dichromate oxidation-volumetric; sodium phosphate extraction-potassium dichromate volumetric; constant temperature culture-hydrochloric acid titration; and anthrone colourimetric.…”

“…Soil has the highest carbon sink storage in terrestrial ecosystems (Tao et al, 2023;Ma et al, 2024). Human farming activities affect carbon deposition, and soil carbon sinks change with human activities (Wang et al, 2022). Black soils are the most fertile soils, providing most of the world's food, and there are three famous black soil belts in the world, the Sanjiang Plain in China belong one of them (Wu et al, 2022).…”

“…All of the cropland in the Sanjiang Plain is located in the black soil zone, where 25% of the soil is albic black soil (also called meadow soil, white pulp soil, albic soil) (Wang et al, 2022). A prerequisite for soil science research is a rigorous soil classification.…”

“…Soil organic carbon (SOC) deposition in the Sanjiang Plain has been described in a previous study (Wang et al, 2022) but how SOC is formed and deposited into the soil has not yet been determined conclusively (Tao et al, 2023). SOC deposition is important for soil fertility and the ecological environment.…”