Contributions of fine mineral particles and active Al/Fe to stabilization of plant material in neutral-to-alkaline soils of Indo-Gangetic Plain

Zhong, R and Lyu, H and Kumari, M and Mishra, A K and Jat, M L and Dahlgren, R A and Funakawa, S and Watanabe, T (2023) Contributions of fine mineral particles and active Al/Fe to stabilization of plant material in neutral-to-alkaline soils of Indo-Gangetic Plain. Geoderma, 440. pp. 1-13. ISSN 0016-7061

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Factors controlling organic carbon stabilization are elusive in neutral-to-alkaline soils, thereby hindering the assessment of carbon sequestration potential across vast agricultural regions like the Indo-Gangetic Plain (IGP). This study investigated controls over mineralization and stabilization of added organic matter in tropical neutralto- alkaline soils with low organic carbon (SOC). Using topsoil and subsoil samples from 12 sites of upper-tolower IGP, we conducted a one-year incubation with and without adding 13C-labeled maize material. We tracked CO2 release and residual C remaining in soil organic matter fractions (free, occluded particulate (oPOM), and mineral-associated organic matter (MAOM)) and analyzed organic matter molecular compositions in incubated soils using pyrolysis-GC/MS. Our results revealed that 48 ± 7 % of added maize C was mineralized, mostly within the first 70 days. Higher active Al/Fe, notably Al, retarded primary maize mineralization by facilitating aggregation. High SOC content and SOC saturation degree resulted in more maize mineralization. The disappearance of maize-unique compounds (e.g., neophytadiene) revealed substantial degradation of added maize. Regarding SOC composition, maize addition increased the relative abundance of fatty acids and decreased that of N-containing compounds. Most residual maize-derived C was found in stabilized fractions, MAOM (77 ± 15 % of residual maize C) and oPOM (8 ± 4 %). Clay fraction contributed to most maize-derived C stabilization as MAOM (path coefficient (β) = 0.81**). Moreover, the significant correlation (P < 0.001) between maize-derived oPOM C and active Al/Fe or clay + silt suggested that active Al/Fe contributed to the stabilization of maize-derived C as oPOM (β = 0.62***) probably by bonding clay and silt particles to form stable aggregates since active Al/Fe content was low (<14 cmol kg-1). Our study highlighted the importance of active Al/Fe in stabilizing SOC, by promoting aggregation and retarding degradation of residue-derived C in neutral-to-alkaline soils.

Item Type: Article
Divisions: Global Research Program - Resilient Farm and Food Systems
Uncontrolled Keywords: Soil organic matter, Fractionation, 13C tracing, Pyrolysis-GC/MS, Clay and silt, Topsoil and subsoil
Subjects: Others > Soil Fertility
Others > Soil
Depositing User: Mr Nagaraju T
Date Deposited: 08 Nov 2023 04:15
Last Modified: 08 Nov 2023 04:15
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Acknowledgement: This work was supported by the JSPS KAKENHI Grant Numbers 17H06171, 19 J14696, 20H04322, 23H03524, and JST SPRING Grant Number JPMJSP2110. We sincerely acknowledge the research partnerships of International Maize and Wheat Improvement Center (CIMMYT) and support of Indian Council of Agricultural Research (ICAR) for this study. We thank Dr. H. S. Jat, Dr. B. Maji, Dr. T. D. Lama (ICARCentral Soil Salinity Research Institute, Karnal and Canning Town), Dr. Ummed Singh (ICAR-Indian Institute of Pulses Research, Kanpur), Dr. R. K Jat (Borlaug Institute of South Asia, Samastipur, Bihar), Dr. A. K. Sinha (Uttar Banga Krishi Vishwavidyalaya, Cooch Behar, West Bangal), and many other researchers and local people for providing information and kind support for the soil sampling in the study regions.
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