Journal of Integrative Agriculture ›› 2025, Vol. 24 ›› Issue (11): 4415-4429.DOI: 10.1016/j.jia.2025.04.039

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四川盆地近40年耕地土壤无机碳变化及其与氮肥施用和降雨的关系

  

  • 收稿日期:2024-12-16 修回日期:2025-04-30 接受日期:2025-03-24 出版日期:2025-11-20 发布日期:2025-10-17

Changes in cropland soil inorganic carbon and its relationship with nitrogen fertilization and precipitation over the past 40 years in the Sichuan Basin, China

Aiwen Li1, Jinli Cheng1, Dan Chen1, Xinyi Chen1, Yaruo Mao1, Qian Deng1, Bin Zhao2, Wenjiao Shi3, 4, Zemeng Fan3, 4, John P. Wilson3, 4, 5, Tianfei Dai6, Tianxiang Yue3, 4, Qiquan Li1#   

  1. 1 College of Resources, Sichuan Agricultural University, Chengdu 611130, China

    2 College of Environmental Sciences, Sichuan Agricultural University, Chengdu 611130, China

    3 Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China

    4 College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China

    5 Spatial Sciences Institute, University of Southern California, Los Angeles, CA 90089-0374, USA

    6 Sichuan Green Food Development Center, Chengdu 610041, China

  • Received:2024-12-16 Revised:2025-04-30 Accepted:2025-03-24 Online:2025-11-20 Published:2025-10-17
  • About author:Aiwen Li, E-mail: ivy_laww@163.com; #Qiquan Li, E-mail: liqq@lreis.ac.cn
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (42330707 and 41930647), the Science Fund for Creative Research Groups of the National Natural Science Foundation of China (72221002), and the Science and Technology Plan of Sichuan Province, China (2022NSFSC0104).

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摘要：

氮(N)肥施用和降雨驱动的土壤酸化对农业生态系统中土壤无机碳(SIC)可长期保持稳定的传统概念提出了挑战。但SIC变化与降雨和氮肥施用的关系仍需进一步明确。本研究以四川盆地1980年代(1980-1985)和2010年代(2017-2019)两个时期分别采集的4000多个土壤样点为基础，建立机器学习模型来填补土壤样点缺失的SIC值，通过配对生成两个时期3697对土壤样点，分析了四川盆地近40年来耕地SIC的变化特征，并探讨了其与降雨量和氮肥施用量的关系。结果表明，四川盆地耕地SIC总体上下降15.73%。SIC变化量随土壤初始pH值和初始SIC含量的变化而变化，并与土壤pH变化量呈指数关系，这表明土壤碳酸盐在提供酸缓冲能力方面的作用随土壤pH变化而改变。SIC下降幅度与氮肥施用量呈抛物线关系，低施氮量有助于减少SIC损失量，而施氮量超过250 kg ha-1 yr-1时，SIC损失量增加。SIC随降雨量呈正弦变化，年均降雨量950 mm为控制SIC增加或减少的阈值。施氮并未改变SOC变化与年均降雨量间的正弦关系，在年均降雨量＜950 mm的地区，高施氮量不会引起SIC损失，而在低施氮量的地区，高降雨量也会导致SIC较大的损失。这些结果表明，SIC变化由降雨和施氮共同驱动，并受到与初始pH值和初始SIC相关的酸缓冲机制控制，其中降雨是主要驱动因素。上述结果说明需要开展更多的区域土壤观测和深入研究SIC变化及其机制，以准确估算区域SIC变化。

Abstract:

Widespread soil acidification driven by nitrogen (N) fertilization and precipitation challenges the conventional notion of the long-term stability of soil inorganic carbon (SIC) in agroecosystems.  However, the changes in SIC with precipitation and N fertilization remain ambiguous.  Based on 4,000+ soil samples collected in the 1980s and 2010s and by developing machine learning models to fill the missing SIC of soil samples, this study generated 3,697 paired soil samples between the two periods and then investigated the cropland SIC change and explored its relationship with precipitation and N fertilization across the Sichuan Basin, China.  The results showed an overall SIC loss, with a decline of the mean SIC by 15.73%.  SIC change varied with initial soil pH and initial SIC and exhibited an exponential relationship with soil pH change, indicating the changing role of carbonates in providing acid-buffering capacity.  There was a parabolical relationship between the magnitude of SIC decline and N fertilizer rates, and low N fertilizer rates contributed to a reduction in SIC loss, while SIC loss was promoted by N fertilization occurred when N fertilizing rates exceeded 250 kg ha–1 yr–1.  The change in SIC showed a sinusoidal variation with precipitation, with 950 mm being the threshold controlling whether SIC increased or decreased.  Meanwhile, N fertilization did not alter the sinusoidal relationship between SIC change and precipitation.  In areas with rainfall<950 mm, the high N fertilizer rate did not cause SIC loss, while higher precipitation could also cause larger SIC loss in areas with lower N fertilizer rates.  These results suggest that SIC dynamics are jointly driven by precipitation and N fertilization and are controlled by acid-buffering mechanisms associated with initial pH and SIC, with precipitation being the predominant driver.  These findings emphasize the need for more regional soil observations and in-depth studies of SIC change and its mechanisms for accurately estimating SIC change.

Key words: soil inorganic carbon change , nitrogen fertilization , precipitation , Sichuan Basin