Paddy soil is an important terrestrial carbon (C) pool. Understanding the impact of organic amendments on soil organic matter (SOM) stabilization pathways is critical for the accurate estimation of C storage potential and SOM stability in paddy soil. However, the impact of organic matter amendment on plant- and microbe-derived C distribution within different SOM fractions, i.e., particulate organic matter (POM) and mineral-associated organic matter (MAOM), remains poorly understood. To address the knowledge gap, five fertilization treatments were selected from a 40-year field experiment: no fertilizer (CK), inorganic NPK fertilizer (NPK), inorganic NPK combined with green manure (GM), inorganic NPK combined with green manure and pig manure (GM+PM), and inorganic NPK combined with green manure and rice straw (GM+RS). The application of organic amendments increased total SOC content through promotion of POM formation. Organic amendments increased both microbe- and plant-derived C contents in POM, and the GM+PM treatment had the greatest impact. In MAOM, organic amendments only altered the proportions of plant- and microbe-derived C, particularly increasing the proportions of bacterial-derived C. Organic amendments also led to the accumulation of less decomposed plant-derived C (C type lignin phenols) in POM, while more decomposed plant-derived C (V type lignin phenols) was stabilized within MAOM. The major factors driving microbe- and plant-derived C fraction distribution varied between the POM and MAOM fraction, i.e., C/N ratio of the exogenous organic materials was the dominant factor in POM, whereas DON and DOC were the primary factors in MAOM. The results of the present study enhance our understanding of the SOC stabilization pathways under organic amendments in paddy soil and offer insights into potential effective soil emissions and fertility management strategies.

中文翻译：

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长期有机改良下稻田土壤不同有机质组分中微生物和植物源碳的累积差异

水稻土是重要的陆地碳库。了解有机改良剂对土壤有机质 (SOM) 稳定途径的影响对于准确估计水稻土中的碳储存潜力和 SOM 稳定性至关重要。然而，有机物改良对不同 SOM 组分（即颗粒有机物（POM）和矿物相关有机物（MAOM））内植物和微生物来源的 C 分布的影响仍然知之甚少。为了解决这一知识空白，通过40年的田间试验，选择了5种施肥处理：不施肥（CK）、无机氮磷钾肥（NPK）、无机氮磷钾配合绿肥（GM）、无机氮磷钾配合绿肥和猪有机肥（GM+PM）、无机氮磷钾配合绿肥和稻草（GM+RS）。有机改良剂的应用通过促进 POM 的形成来增加总 SOC 含量。有机改良剂增加了 POM 中微生物和植物来源的 C 含量，其中 GM+PM 处理的影响最大。在MAOM中，有机改良剂仅改变了植物和微生物来源的C的比例，特别是增加了细菌来源的C的比例。有机改良剂还导致POM中分解程度较低的植物来源的C（C型木质素酚）的积累，而更多分解的植物源 C（V 型木质素酚）在 MAOM 中稳定。驱动微生物和植物源C组分分布的主要因素在POM和MAOM组分之间存在差异，即外源有机物质的C/N比是POM中的主导因素，而DON和DOC是MAOM​​中的主要因素。本研究的结果增强了我们对水稻土有机改良下 SOC 稳定途径的理解，并为潜在有效的土壤排放和肥力管理策略提供了见解。