Exogenous fulvic acid enhances stability of mineral-associated soil organic matter better than manure

• Published in: Environmental science and pollution research international Vol. 29; no. 7; pp. 9805 - 9816
• Main Authors: Zhang, Yang, Zhang, Xiaojia, Wen, Jiong, Wang, Yanan, Zhang, Nan, Jia, Yuehui, Su, Shiming, Wu, Cuixia, Zeng, Xibai
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2022; Springer Nature B.V
• Subjects: Acidic soils; Acids; Aluminum; Aluminum oxide; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Benzopyrans; Carbon; Carbon sequestration; Coefficients; Coordination compounds; Decomposing organic matter; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fertilization; Fertilizers; Fertilizers - analysis; field experimentation; Fulvic acids; Humus; iron; Iron oxides; Land degradation; Manure; manure spreading; Manures; Meta-analysis; Metal oxides; Mineral fertilizers; Minerals; Organic carbon; Organic materials; Organic matter; Research Article; Soil; Soil amendment; soil amendments; Soil degradation; soil organic carbon; Soil organic matter; Soil stability; Soils; Stability analysis; Waste Water Technology; Water Management; Water Pollution Control; Exogenous organic materials; Organic fertilization; Metal oxide complexation; Mineral-organic association; Humus stabilization
• ISSN: 0944-1344; 1614-7499; 1614-7499
• DOI: 10.1007/s11356-021-16382-0

Mineral-associated soil organic matter (MAOM) is seen as the key to soil carbon sequestration, but its stability often varies with types of exogenous organic materials. Fulvic acid and manure are ones of the exogenous organic materials used for the improvement of degraded soil. However, little is known about if and how fulvic acid and manure affect the stability of MAOM. Using a field experiment of four fertilization treatments (no fertilization, mineral fertilizers, fulvic acid, and manure) and a comprehensive meta-analysis using relevant studies published prior to January 2020, we investigated effects of exogenous fulvic acid and manure applications on four MAOM stability indexes: association intensity, humus stabilization index, iron oxide complex coefficient, and aluminum oxide complex coefficient. Exogenous fulvic acid and manure applications increased soil organic carbon fractions by 26.04–48.47%, MAOM stability by 12.26–387.41%, and complexed iron/aluminum contents by 16.12–20.01%. Fulvic acid application increased MAOM stability by promoting mineral oxide complexation by 20.33% and manure application improved MAOM stability via increasing humus stabilization by 21–25%. Association intensity was positively correlated with contents of soil carbon fractions and the metal oxide complex coefficients were positively correlated with iron/aluminum oxide contents. Moreover, stable-humus exerted significantly positive direct and indirect effects on association intensity and humus stabilization index, while amorphous iron/aluminum content had significantly negative influences on metal oxide complex coefficients. The meta-analysis verified that long-term fulvic acid application improved MAOM stability more so than manure application in acidic soils. We recommend that strategies aiming to prevent land degradation should focus on the potential of fulvic acid as a soil amendment because it can significantly increase MAOM stability.