Land management policy shift influenced seasonal variation of erosion-induced nitrogen and phosphorus outputs from intensive agricultural catchment

Zhaoyang Lu; Hanqing Yu; Joseph Adu-Gyamfi; Hongyu Wang; Adrian Chappell; Suarau Odutola Oshunsanya; Wenxiang Liu; Tingting Xue; Lee Heng

doi:10.1016/j.scitotenv.2024.170590

Land management policy shift influenced seasonal variation of erosion-induced nitrogen and phosphorus outputs from intensive agricultural catchment

Sci Total Environ. 2024 Mar 25:918:170590. doi: 10.1016/j.scitotenv.2024.170590. Epub 2024 Feb 2.

Authors

Zhaoyang Lu¹, Hanqing Yu², Joseph Adu-Gyamfi³, Hongyu Wang¹, Adrian Chappell⁴, Suarau Odutola Oshunsanya⁵, Wenxiang Liu⁶, Tingting Xue¹, Lee Heng³

Affiliations

¹ Agricultural Clean Watershed Research Group, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences (CAAS), Haidian District, 100081 Beijing, China.
² Agricultural Clean Watershed Research Group, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences (CAAS), Haidian District, 100081 Beijing, China. Electronic address: yuhanqing@caas.cn.
³ International Atomic Energy Agency, Vienna, Austria.
⁴ School of Earth and Environmental Sciences, Cardiff University, Cardiff, UK.
⁵ Agricultural Clean Watershed Research Group, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences (CAAS), Haidian District, 100081 Beijing, China; Department of Agronomy, University of Ibadan, Nigeria.
⁶ Agricultural Clean Watershed Research Group, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences (CAAS), Haidian District, 100081 Beijing, China; Chongqing Branch Institute, Changjiang River Scientific Research Institute, 400026 Chongqing, China.

PMID: 38311083
DOI: 10.1016/j.scitotenv.2024.170590

Abstract

A shift in policy to intensive agricultural production and land management often leads to excessive fertilizer application and accelerated erosion with consequent detrimental effects to water bodies. We investigated the impact of that shift by quantifying the spatial and temporal change in sediment sources and associated total nitrogen (TN) and total phosphorus (TP) pollutants output loads in an intensive agricultural catchment in North China across one year (November 2021-November 2022). We describe the implications of this work for intensive agriculture elsewhere in China and other countries. Seasonal sediment source apportionment was estimated at the catchment outlet using Berillium-7 (⁷Be) combined with compound-specific stable isotope (CSSI) signatures from sources and sediments. Diagnostic 'fingerprints' in MixSIAR were used to discriminate sediment sources between forest and crop farmland converted from forest (F + C(F)), crop farmland (C), and vegetable farmland (V). Our study identified F + C(F) as the dominant sediment source (mean 55.24 ± 2.91 %), intermediate on V (mean 30.06 ± 2.20 %), and least on C (mean 14.70 ± 2.13 %). Sedimentation ranged from 37.98 ± 3.02 to 89.60 ± 12.68 t·ha^-1·event^-1 and coincided with shifted land use policy and rainfall distribution. The TN and TP in sediment were both mainly derived from F + C(F) (averaged 22.27 ± 4.26 t·event^-1 and 11.62 ± 2.28 t·event^-1) and least from V (averaged 1.63 ± 0.29 and 2.09 ± 0.33 t·event^-1). Despite being a significant sediment source, V contributed little sediment TN and TP input for eutrophication. Our findings imply that F + C(F) are diffuse sources of catchment pollution over the short term. These results describe the successful use of CSSI and ⁷Be to cost-effectively quantify the seasonal variation of sediment TN and TP loads from land-use-specific sources in the catchment under shifting land management policy in China with potential for use elsewhere. These findings enable soil conservation strategies and land management practices optimized for implementing targeted pollutant abatement initiatives in intensive agriculture in China and elsewhere.

Keywords: Berillium-7; Compound specific stable isotope; Exported load of TN and TP; Seasonal variation; Sediment source contribution.