文獻信息：
Zhang Xinmu, Guo Jingheng*, Vogt Rolf David, Mulder Jan, Wang Yajing, Qian Cheng, Wang Jingguo, Zhang Xiaoshan. Soil acidification as an additional driver to organic carbon accumulation in major Chinese croplands. Geoderma, 2020, 366: 114234. DOI: 10.1016/j.geoderma.2020.114234
此論文爭議性較大，想了解更多請查閱以下兩篇相關文獻：
[1] Kuzyakov Yakov*, Kuzyakova Irina, Raza Sajjad, Zhou Jianbin, Zamanian Kazem*. Does acidification really increase soil carbon in croplands? How statistical analyses of large datasets might mislead the conclusions. Geoderma, 2020. DOI: 10.1016/j.geoderma.2020.114806
[2] Zhang Xinmu, Guo Jingheng*, Vogt Rolf David, Mulder Jan, Wang Jingguo. Response to the comments from Kuzyakov et al: Acidification-induced increase in soil organic carbon: statistical rationale, biogeochemical mechanisms and agro-environmental consequences. Geoderma, 2020. DOI: 10.1016/j.geoderma.2020.114807
摘 要：中國農田土壤有機碳（SOC）顯著增加。目前文獻將其主要歸因於有機肥、農作物秸稈和根系有機碳輸入的增加。然而，通過對中國185個長期試驗和6669個空間數據進行Meta分析，研究發現土壤酸化是土壤有機碳積累的另一個重要原因。長期試驗結果表明，過量施氮引起的土壤酸化與觀測到的土壤有機碳累積相吻合，且貢獻顯著（p <0.01）。在空間上，土壤酸化引起的土壤有機碳增加量隨初始含量的增加而降低。此外，隨著土壤pH值的降低，土壤的基礎呼吸速率（SBRR）、微生物代謝商（MMQ）和可溶性有機碳（DOC）佔總有機碳的比例顯著降低（p<0.01）。這表明土壤酸化通過降低微生物活性和增加礦物相（mineral phases）對有機質的保護作用來抑制有機質的分解。因此，氮誘導的土壤酸化通過提高土壤有機碳的穩定性來促進土壤有機碳的積累。這與當前強調有機碳輸入重要性的觀點不同，本研究的Meta分析揭示了一種將施氮與農業生態系統中有機碳積累聯繫起來的替代機制。同時，也需要更多的研究來進一步闡明其操作過程、相對重要性和農業環境後果。
Fig. 1. Geographical distribution of data collected. Red dots show the location of the 46 long-term experimental sites and the green dots represent the 5942 regional sites with data pairs of pH and SOC.
Fig. 2.Comparison of linear regression results between soil pH and SOC at 3 sites, using original data (a) and [0, 1] normalized data (b).
Fig. 3. Long-term (10–34 years) changes in soil pH (a) and soil organic carbon (SOC) concentration (b) under zero-fertilization (ZF) and farmer’s conventional fertilization (CF) at 46 experimental sites. The line and square within the box represent the median and mean values of all data; the bottom and top edges of the box represent 25 and 75 percentiles of all data, respectively; and the bottom and top bars represent 5 and 95 percentiles, respectively.
Fig. 4. Relationship between [0, 1] normalized SOC concentration and soil pH (a) and grain yield (b). Red solid lines and light gray areas indicate regression lines and their 95% confidence intervals, respectively.
Table 1 Partial correlations of SOC as response factor with grain yield and soil pH as explanatory variables. Data from 46 long-term monitored experimental sites in China are used in the statistical analysis. All data were transformed by [0, 1] normalization as Eq. (1).
* Grain yields at 10 plots were not available.
Fig. 5. Relationships between soil pH and soil organic carbon (SOC) concentration in four soil groups. Data numbers are 2303, 1154, 1654, and 710, for soil group I, II, III and IV, respectively. Red solid lines and color areas indicate regression lines and their 95% confidence intervals, respectively. Figure with original data points is presented as Fig. S5.
Fig. 6. Relationships between soil pH and biogeochemical response parameters. The exponential correlation to soil basal respiration rate (SBRR) is shown in figure (a), exponential correlation to microbial metabolic quotient (MMQ) in figure (b), and the linear correlation to percentage of dissolved organic carbon (DOC) relative to the soil organic carbon (SOC) is given in figure (c). Red solid lines and light gray areas indicate regression lines and their 95% confidence intervals, respectively.