Chen Zixun, Du Zhangliu, Zhang Zeyu, Wang Guoan, Li Ji
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China; Organic Recycling Institute (Suzhou) of China Agricultural University, Wuzhong District, Suzhou 215128, China.
Sci Total Environ. 2024 Feb 25;913:169407. doi: 10.1016/j.scitotenv.2023.169407. Epub 2023 Dec 18.
Soil organic carbon (SOC) plays a vital role in improving soil quality and alleviating global warming. Understanding the dynamic changes in SOC is crucial for its accumulation induced by compost application in agroecosystem. In this study, soil samples were collected from three treatments: high-rate bio-compost (BioM), low-rate bio-compost (BioM), and control (CK, no fertilization) during 2002-2020 in a wheat-maize double cropping system in North China. The soils were separated into three functional fractions, i.e., coarse particle organic matter (cPOM, >250 μm), microaggregates (μAgg, 53-250 μm) and mineral-associated organic matter (MAOM, < 53 μm), and the associated SOC contents were determined. During 1993-2002, SOC contents in bulk soil significantly increased with the duration in the BioM and BioM plots. However, there was no significant correlation between SOC content and duration during 2002-2020. These results suggested that compost application positively improved SOC sequestration, while the duration of SOC sequestration (i.e., the longevity of increased SOC with time) under compost inputs maintained only 9 years. Moreover, there was a significant increase in mean annual SOC contents in bulk soil with compost application rate during 2002-2020, indicating that carbon saturation did not occur. Additionally, the SOC contents in the cPOM fraction increased with time (p < 0.01), but the corresponding μAgg and MAOM associated SOC was insignificant (p > 0.05). The MAOM fraction exhibited no additional carbon accumulation with expanding compost application, confirming a hierarchical carbon saturation in these fractions. We concluded that soils under wheat-maize double cropping system in North China have greater potential to sequester C through additional compost inputs, despite showing hierarchical saturation behavior in the non-protected coarse particulate fraction.
土壤有机碳（SOC）在改善土壤质量和缓解全球变暖方面发挥着至关重要的作用。了解SOC的动态变化对于其在农业生态系统中因施用堆肥而产生的积累至关重要。在本研究中，于2002年至2020年期间，在中国北方的小麦-玉米复种系统中，从三种处理中采集土壤样本：高量生物堆肥（BioM）、低量生物堆肥（BioM）和对照（CK，不施肥）。将土壤分为三个功能组分，即粗颗粒有机物（cPOM，>250μm）、微团聚体（μAgg，53 - 250μm）和矿物结合有机物（MAOM，<53μm），并测定相关的SOC含量。在1993年至2002年期间，BioM和BioM小区的耕层土壤SOC含量随时间显著增加。然而，在2002年至2020年期间，SOC含量与时间之间没有显著相关性。这些结果表明，施用堆肥对SOC固存具有积极作用，而在堆肥投入下SOC固存的持续时间（即SOC随时间增加的持续时间）仅维持9年。此外，在2002年至2020年期间，耕层土壤的年均SOC含量随堆肥施用量显著增加，表明未发生碳饱和。此外，cPOM组分中的SOC含量随时间增加（p<0.01），但相应的μAgg和MAOM相关SOC不显著（p>0.05）。随着堆肥施用量的增加，MAOM组分未表现出额外的碳积累，证实了这些组分中存在分层碳饱和。我们得出结论，尽管在中国北方小麦-玉米复种系统的土壤中，非保护性粗颗粒组分表现出分层饱和行为，但通过额外施用堆肥，土壤具有更大的固碳潜力。
