CRITICAL PROCESSES AND MAJOR FACTORS THAT DRIVE NITROGEN TRANSPORT FROM FARMLAND TO SURFACE WATER BODIES

Highlights

● This study clarified the critical processes and major factors that nitrogen transport from farm fields to surface water bodies.

● Soil storage, exogenous inputs and meteorological hydrology were found to influence nitrogen loss from farmland.

● Hydrology, biogeochemistry and nitrogen inputs were found to influence the transformation of nitrogen in the ditches and rivers.

Abstract

Agricultural non-point source pollution is increasingly an important issue affecting surface water quality. Currently, the majority of the studies on nitrogen loss have focused on the agricultural field scale, however, the response of surface water quality at the watershed scale into the nitrogen loss at the field scale is poorly understood. The present study systematically reviewed the critical processes and major factors that nitrogen transport from farm fields to surface water bodies. The critical processes of farmland nitrogen entering surface water bodies involve the processes of nitrogen transport from farmland to ditches and the transformation processes of nitrogen during migration in ditches/rivers. Nitrogen transport from farmland to ditches is one of the prerequisites and critical processes for farmland nitrogen transport to surface water bodies. The transformation of nitrogen forms in ditches/rivers is an intermediate process in the migration of nitrogen from farmland to surface water bodies. Nitrogen loss from farmland is related to soil storage and exogenous inputs. Therefore, nitrogen input management should not only consider the current input, but also the contribution of soil storage due to the historical surpluses. Ditches/rivers have a strong retention capacity for nitrogen, which will significantly affect the process of farmland nitrogen entering surface water bodies. The factors affecting nitrogen transformation in river/ditches can be placed in four categories: (1) factors affecting hydraulic retention time, (2) factors affecting contact area, (3) factors affecting biological activity, and (4) forms and amount of nitrogen loading to river/ditches. Ditch systems are more biologically (including plants and microbes) active than rivers with biological factors having a greater influence on nitrogen transformation. When developing pollution prevention and control strategies, ecological ditches can be constructed to increase biological activity and reduce the amount of surplus nitrogen entering the water body. The present research should be valuable for the evaluation of environment impacts of nitrogen loss and the non-point source pollution control.

Graphical abstract

Keywords

nitrogen / loss from soil / transformation / farm field scale / watershed scale

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Acknowledgements

This work was financially supported by the Key S&T Special Project of Yunnan Province (202202AE090034), the National Natural Science Foundation of China (42107410), the Science and Technology Project of Hebei Education Department (BJ2021026), the Hebei Financial Aid Program for Introduced Overseas Scholars (C20200330), the Taishan Industry Leading Talents High-Efficiency Agriculture Innovation Project (LJNY202125), and the Expert Workstation of Dali.

Compliance with ethics guidelines

Wenchao Li, Wen Xu, Gaofei Yin, Xulin Zhang, Zihan Zhang, Bin Xi, Qiuliang Lei, Limei Zhai, Qiang Zhang, Linzhang Yang, and Hongbin Liu declare that they have no conflicts of interest or financial conflicts to disclose. This article does not contain any studies with human or animal subjects performed by any of the authors.

RIGHTS & PERMISSIONS

The Author(s) 2023. Published by Higher Education Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0)