Denitrification Rate and Controlling Factors for Accumulated Nitrate in the Deep Subsoil of Intensive Farmlands: A Case Study in the North China Plain  

作　　者：YUAN Haijing QIN Shuping DONG Wenxu HU Chunsheng Kiril MANEVSKI LI Xiaoxin 

机构地区：[1]Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021 (China) [2]University of Chinese Academy of Sciences, Beijing 100049 (China) [3]Department of Agroecology, Aarhus University, Tjele 8830 (Denmark)

出　　处：《Pedosphere》2019年第4期516-526,共11页土壤圈（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.31270554 and41301323);the Key Program of National Natural Science Foundation of China(No.41530859)

摘　　要：Denitrification in subsoil(to a depth of 12 m) is an important mechanism to reduce nitrate(NO3^-) leaching into groundwater.However, regulating mechanisms of subsoil denitrification, especially those in the deep subsoil beneath the crop root zone, have not been well documented. In this study, soil columns of 0–12 m depth were collected from intensively farmed fields in the North China Plain. The fields had received long-term nitrogen(N) fertilizer inputs at 0(N0), 200(N200) and 600(N600) kg N ha^-1 year^-1. Main soil properties related to denitrification, i.e., soil water content, NO3^-, dissolved organic carbon(DOC), soil organic carbon(SOC),pH, denitrifying enzyme activity(DEA), and anaerobic denitrification rate(ADR), were determined. Statistical comparisons among the treatments were performed. The results showed that NO3^- was more heavily accumulated in the entire soil profile of the N600 treatment, compared to the N0 and N200 treatments. The SOC, DOC, and ADR decreased with increasing soil depth in all treatments,whereas considerable DEA was observed throughout the subsoil. The long-term fertilizer rates affected ADR only in the upper 4 m soil layers. The ADRs in the N200 and N600 treatments were significantly correlated with DOC. Multiple regression analysis indicated that DOC rather than DEA was the key factor regulating denitrification beneath the root zone. Additional research is required to determine if carbon addition into subsoil can be a promising approach to enhance NO3^- denitrification in the subsoil and consequently to mitigate groundwater NO3^- contamination in the intensive farmlands.Denitrification in subsoil（to a depth of 12 m） is an important mechanism to reduce nitrate（NO3-） leaching into groundwater.However, regulating mechanisms of subsoil denitrification, especially those in the deep subsoil beneath the crop root zone, have not been well documented. In this study, soil columns of 0–12 m depth were collected from intensively farmed fields in the North China Plain. The fields had received long-term nitrogen（N） fertilizer inputs at 0（N0）, 200（N200） and 600（N600） kg N ha-1 year-1. Main soil properties related to denitrification, i.e., soil water content, NO3-, dissolved organic carbon（DOC）, soil organic carbon（SOC）,pH, denitrifying enzyme activity（DEA）, and anaerobic denitrification rate（ADR）, were determined. Statistical comparisons among the treatments were performed. The results showed that NO3- was more heavily accumulated in the entire soil profile of the N600 treatment, compared to the N0 and N200 treatments. The SOC, DOC, and ADR decreased with increasing soil depth in all treatments,whereas considerable DEA was observed throughout the subsoil. The long-term fertilizer rates affected ADR only in the upper 4 m soil layers. The ADRs in the N200 and N600 treatments were significantly correlated with DOC. Multiple regression analysis indicated that DOC rather than DEA was the key factor regulating denitrification beneath the root zone. Additional research is required to determine if carbon addition into subsoil can be a promising approach to enhance NO3- denitrification in the subsoil and consequently to mitigate groundwater NO3- contamination in the intensive farmlands.

关 键 词：denitrifying enzyme activity dissolved ORGANIC CARBON NITRATE leaching soil ORGANIC CARBON SUBSOIL DENITRIFICATION 

分 类 号：P[天文地球]