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Updated: Jan 14, 2026

Understanding Dissolved Organic Matter Biogeochemistry Through In Situ Nutrient Manipulations in Stream Ecosystems
Published on: October 29, 2016
Divergent regulation of dissolved organic nitrogen release from agricultural wastes: Iron-Aluminum-Organic carbon
Bingcong Feng1, Jie Ma1, Yong Liu1
1Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China.
Abstract:
The leaching of dissolved organic nitrogen (DON) from agricultural waste contributes to groundwater pollution, yet the regulatory soil factors and mechanisms-particularly those linked to DON source properties-remain poorly understood. We investigated the transport of wheat-straw-derived DON (WS-DON) and chicken-manure-derived DON (CM-DON) in representative regional Chinese soils using an integrated multiscale approach, including soil column experiments, convection-dispersion modeling, machine learning models (random forest with SHapley Additive exPlanations), partial least squares path modeling, and quantum chemical calculations. CM-DON exhibited 55.6 % higher mobility than WS-DON. While total iron (Fe-t), exchangeable aluminum (Al-e), and total organic carbon (TOC) influenced both DON types, their regulatory roles differed. Fe-t (coefficient = 0.65) and TOC (0.42) enhanced WS-DON retention, with Al-e contributing indirectly via synergy with the Fe-TOC system. In contrast, CM-DON retention was mainly driven by the direct effects of Fe-t (0.69) and easily reducible Fe (Fe-ox1, 0.40), modulated by TOC-pH-Fe-ox1 indirect pathways. Quantum chemical analysis revealed that goethite retained hydroxyl-rich WS-DON via Fe-O stable covalent bonds (ΔE = -21.75 kcal mol-1), whereas CM-DON was weakly adsorbed through humic-acid-mediatd clustering. These results highlight the need for differentiated nutrient management strategies to mitigate DON leaching from agricultural residues.
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