Vertical dynamics of soil organic carbon and its influence on Chengdu Plain paddy soils from the 1980s to the 2010s

ABSTRACT

The vertical dynamics of paddy soil organic carbon (SOC) play an important role in soil quality and carbon cycling. In this study, we used an exponential decay function to estimate the vertical dynamics of SOC content and determined its influencing factors in a typical paddy soil area of the Chengdu Plain from the 1980s to the 2010s. Our results show an overall increase in SOC stocks at 0–100 cm from 11.8 Tg in the 1980s to 13.7 Tg in the 2010s. SOC content increased at depths of 0–40 cm and declined at depths of 40–100 cm over the past three decades. The exponential decay function parameters C₀ and k significantly increased by 31.4% and 18.2% respectively, which suggests the vertical pattern of SOC distribution changed. The increase in nugget effects of C₀ and k and the decrease in the relative contributions of the parent material, subgroup and distance-to-river indicate that extrinsic factors played increasing roles in the vertical variation of SOC content. Our study concludes that rice planting has led to vertical variations of SOC content and decreased the effects of intrinsic factors on the vertical variation of SOC content of Chengdu Plain paddy soils over the past three decades.

KEYWORDS:

• SOC
• spatial-temporal variation
• vertical distribution
• exponential decay function
• influencing factors
• soil organic carbon

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Science and Technology Support Plan of Sichuan Province [2017SZ0188]; the National Key Research and Development Program of China [SQ2018YFD080041].