Dual Role of Iron Oxides in Stabilizing Particulate and Mineral-Associated Organic Carbon Under Field Management in Paddies

Hang Guo, Linxian Liao, Junzeng Xu (), Wenyi Wang, Peng Chen, Zhihui Min, Yajun Luan, Yu Han and Keke Bao ()
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Hang Guo: College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China
Linxian Liao: College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China
Junzeng Xu: College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China
Wenyi Wang: Hefei Eastern New Centre Construction Investment Co., Ltd., Hefei 230000, China
Peng Chen: College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China
Zhihui Min: College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China
Yajun Luan: College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China
Yu Han: School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, China
Keke Bao: Zhejiang Zoneking Environmental Protection Technology Co., Ltd., Hangzhou 310000, China

Agriculture, 2025, vol. 15, issue 13, 1-18

Abstract: The interactions between iron oxides and organic carbon within the particulate organic matter (POM) and mineral-associated organic matter (MAOM) fractions in paddy soils remain insufficiently understood, yet they are likely crucial for unlocking the carbon sequestration potential of these systems. In this study, we investigated the distribution of soil iron oxides and organic carbon within POM and MAOM fractions following 10 years of continuous irrigation and organic amendment management. We also examined the relationship between iron oxide transformation and these two SOC (soil organic carbon) fractions. Our results demonstrated that, under both flooded irrigation and controlled irrigation regimes, straw return or manure application effectively enhanced soil carbon sequestration, as evidenced by increases in both POM-C (POM-associated organic carbon) and MAOM-C (MAOM-associated organic carbon) contents. Meanwhile, exogenous carbon inputs promoted the transformation of crystalline iron oxides into short-range ordered iron oxides and iron oxide colloids, thereby enhancing the activation and complexation degree of soil iron oxides and facilitating the formation of Fe-bound organic carbon. Further regression analysis revealed that the activation degree of iron oxides had a stronger influence on POM-C, whereas the complexation degree had a greater effect on MAOM-C. This implies that exogenous carbon inputs are effective in promoting soil carbon sequestration in both flooded and water-saving irrigated rice paddies and that iron oxide transformation plays a key role in mediating this effect.

Keywords: paddy; soil organic carbon; soil iron oxides; particulate organic matter; mineral-associated organic matter (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2025
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