Xuejun Liu

Xuejun Liu
China Agricultural University | CAU · College of Resources and Environmental Sciences

PhD degree

About

352
Publications
107,434
Reads
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19,557
Citations
Introduction
I am Professor of Environmental Science at China Agricultural University (CAU). I got my PhD degree in plant nutrition in 1997 at CAU. I have being engaged in studies on nitrogen (N) cycling in particular on the N source, fate and their impacts on soil acidification, eutrophication and greenhouse gas emissions in major Chinese croplands, with 160 peer-reviewed SCI papers in a number of international top journals including Nature, Science and PNAS, with H-index 43. I have established wide international cooperation with Hohenheim University (Germany), Rothamsted Research and Centre for Ecology & Hydrology (UK), and Colorado State University and Stanford University (USA) as well as Wageningen University (NL) in his scientific career. I have got support by China National Funds for Distinguished Young Scientists (2014), the national Ten-thousand Talents Program (2016) and China's Key Research & Development Programme. My current research interests are atmospheric N deposition, PM2.5 and non-point source pollution, NH3 mitigation and impacts on food security, ecosystem and human health.
Additional affiliations
January 2009 - December 2013
Chinese Academy of Sciences
Position
  • Guest Professor
November 2008 - January 2009
University of Hohenheim
Position
  • Guest Prof.
June 1997 - present
China Agricultural University
Position
  • Professor
Education
September 1994 - June 1997
China Agricultural University
Field of study
  • Crop nutrition and fertilization
September 1991 - July 1994
Hunan Agricultural University
Field of study
  • Soil chemistry
September 1987 - July 1991
Hunan Agricultural University
Field of study
  • Soil Science and Plant Nutrition

Publications

Publications (352)
Article
We investigated variations of PM2.5 and water-soluble inorganic ions chemical characteristics at nine urban and rural sites in China using ground-based observations. From 2015 to 2019, mean PM2.5 concentration across all sites decreased by 41.9 µg/m³ with a decline of 46% at urban sites and 28% at rural sites, where secondary inorganic aerosol (SIA...
Article
Fertilized cropland is a significant source of ammonia (NH 3) emissions. Urea, the dominant synthetic nitrogen (N) fertilizer, makes the largest contribution to NH 3 volatilization from cropland in China. To improve environmental quality and resource utilization efficiency, stabilized urea (UI: Urea amended with the urease inhibitor Limus®) was tes...
Article
Airborne bacteria are important components of fine particulate matter (PM2.5), and have received increasing attention because of their impacts on public health and ecological systems. However, the relationships between the bacterial community and PM2.5 pollution are poorly understood. The properties of bacterial communities in Beijing at low, mediu...
Article
Excessive application of chemical nitrogen (N) fertilizer and inefficient N management are still common in the North China Plain, leading to large reactive N (Nr) losses and pollution, threatening environmental security and public health. Three improved N management practices (33% reduction in N applied (OU), OU combined with partial organic fertil...
Article
Water-soluble organic acids (WSOAs) are important chemical components of fine particulate matter (PM2.5). WSOAs can aggravate PM2.5 pollution and contribute to the acidity of aerosol and rain. PM2.5 pollution in the North China Plain (NCP) has been extensively researched. However, with the decrease in PM2.5 and enhancement of atmospheric oxidation...
Article
Ammonia (NH3) is the most important alkaline gas in the atmosphere, which has negative effects on biodiversity, ecosystems, soil acidification and human health. China has the largest NH3 emissions globally, mainly associated with agricultural sources including nitrogen fertilizer and livestock. However, there is still a limited number of ground mon...
Article
Full-text available
Aims Litter decomposition is a crucial component of nutrient recycling. Short-term nitrogen (N) deposition has been shown to influence litter decomposition in temperate steppe with significant variability due to differences in atmospheric N deposition, species identity, and experimental duration. Therefore, the effect of N addition, especially long...
Article
Full-text available
Since the 1980s, the widespread use of N fertilizer has not only resulted in a strong increase in agricultural productivity but also caused a number of environmental problems, induced by excess reactive N emissions. A range of approaches to improve N management for increased agricultural production together with reduced environmental impacts has be...
Article
Full-text available
Nitrogen (N) enrichment has substantially altered patterns of terrestrial litter decomposition, with positive, neutral, and negative effects. However, the general response patterns and drivers of litter decomposition to N enrichment rates are poorly understood, and how litter decomposition has changed under the N enrichment rate, especially in diff...
Article
Full-text available
Terrestrial ecosystems in China receive the world’s largest amount of reactive nitrogen (N) deposition. Recent controls on nitrogen oxides (NO x = NO + NO 2 ) emissions in China to tackle air pollution are expected to decrease N deposition, yet the observed N deposition fluxes remain almost stagnant. Here we show that the effectiveness of NO x emis...
Article
Full-text available
Atmospheric ammonia (NH3) is the key precursor in secondary particle formation, which is identified as the most abundant components of haze in Beijing in most cases. It is critical to understand the characteristics of NH3 from various emission sources and quantify each source contribution to NH3 in ambient atmosphere. Stable nitrogen (N) isotope co...
Article
Full-text available
Livestock and crop production are the main sources of ammonia (NH3) emissions, which are known to degrade the air quality. Numerous studies have been conducted to explore the mitigation potential of various approaches, although few have examined the systematic NH3 emission mitigation potential when considering both crop and livestock systems based...
Article
Litter decomposition is an important component of the nutrient recycling process and is highly sensitive to climate change. However, the impacts of warming and increased precipitation on litter decomposition have not been well studied, especially in the alpine grassland of Tianshan Mountains. We conducted a manipulative warming and increased precip...
Article
Full-text available
The Chinese government recently proposed ammonia (NH3) emission reductions (but without a specific national target) as a strategic option to mitigate fine particulate matter (PM2.5) pollution. We combined a meta-analysis of nationwide measurements and air quality modeling to identify efficiency gains by striking a balance between controlling NH3 an...
Article
Full-text available
Significance Agricultural systems are already major forces of ammonia pollution and environmental degradation. How agricultural ammonia emissions affect the spatio-temporal patterns of nitrogen deposition and where to target future mitigation efforts, remains poorly understood. We develop a substantially complete and coherent agricultural ammonia e...
Preprint
Full-text available
Ammonia (NH3) is the most important alkaline gas in the atmosphere, which has negative effects on biodiversity, ecosystems, soil acidification and human health. China has largest NH3 emissions in the world mainly associated with agricultural sources including nitrogen fertilizer and livestock. However, there is still a limited number of ground moni...
Article
Full-text available
Swift changes in both industrialization and pollution control in China over the past 15 years have created a complex and evolving relationship between emission sources and the depositional sinks of air pollutants. Here, by combining an emissions inventory, an air quality model and a statistical model to estimate bulk deposition (wet plus a part of...
Article
Atmospheric deposition is an important pathway for the input of anthropogenic and natural nutrients to terrestrial and aquatic ecosystems. However, previous measurements focused mainly on hotspot locations, ignoring the fact that the deposition magnitudes of various nutrient species (e.g., nitrogen (N), phosphorus (P)) at a national scale should be...
Article
Soil quality on smallholder farms is progressively declining due to inappropriate land management and agricultural inputs. Assessing soil quality at the field scale and evaluating the contributions of agricultural inputs to soil quality is therefore important in the formulation of policies and technologies for improving the land management practice...
Article
Many Chinese croplands are suffering from soil acidification, defined as a decrease in soil acid neutralizing capacity (ANC), due to over-application of nitrogen (N) fertilizer and removal of base cations (BCs) in crop harvest. The contribution of fertilization and harvesting on soil acidification rates for different cropping systems is, however, s...
Article
Full-text available
Emissions of reactive nitrogen as ammonia (NH3) and nitrogen oxides (NOx), together with sulfur dioxide (SO2), contribute to formation of secondary PM2.5 in the atmosphere. Satellite observations of atmospheric NH3, NO2, and SO2 levels since the 2000s provide valuable information to constrain the spatial and temporal variability of their emissions....
Article
Functional genes involved in nitrogen (N) cycling regulate soil nitrification, denitrification and N2O emissions. However, the general patterns and variability of N functional genes in response to N addition, and their association with N2O emission have not been synthesized for terrestrial ecosystems. We synthesized 2068 observations from 144 paper...
Article
Full-text available
Studies of soil Cd and Zn are often performed on sites that are contaminated or have deficient Zn conditions. Soil characteristics and crop management could impact the soil mobility and uptake of Cd and Zn, even when considering unpolluted Cd soils and adequate soil Zn levels. The concentrations of these two metals were assessed in soil and silage...
Conference Paper
Full-text available
Atmospheric nitrogen (N) deposition has increased dramatically due to increased human activities since the industrial revolution. However, it is still unclear what the responses of soil nitrous oxide (N2O) is to long-term elevated N deposition in a temperate grassland. Here, we conducted an in situ field experiment to investigate these responses to...
Article
Ammonia (NH3) emissions mostly from agriculture result in air pollution and degrade human health. However, a full picture of soil NH3 emissions and associated abatement in cropping systems are not well understood. Here we present a thorough analysis of cropland NH3 emissions, discuss mitigation potential and assess associated abatement costs. Globa...
Article
Nitrogen (N) management is essential for food security. The North China Plain is an important food producing region, but also a hotspot of N losses to the environment. This results in water, soil, and air pollution. In this study, we aim to quantify the relative contribution of different crops and animals to N losses, by taking the Quzhou County as...
Preprint
Full-text available
The Chinese government recently proposed ammonia (NH3) emissions reductions (but without a specific national target) as a strategic option to mitigate PM2.5 pollution. We combined a meta-analysis of nationwide measurements and air quality modelling to identify efficiency gains by striking a balance between controlling NH3 and acid gas (SO2 and NOx)...
Article
Global changes in precipitation and atmospheric N deposition affect the geochemical cycle of the element and its hydrological cycle in the ecosystem. It may also affect the relationship between plant water use efficiency (WUE) and nutrients, as well as the relationship between plant nutrients. Desert ecosystems are vulnerable to global changes. Hal...
Article
Agricultural soil is the main source of nitrous oxide (N2O) emissions which contribute to global warming and stratospheric ozone depletion. In recent decades, atmospheric nitrogen (N) deposition has increased dramatically as an important agricultural soil N input, while its impact on soil N2O emissions under the current and future climate change re...
Article
Full-text available
Nitrogen (N) addition has profound impacts on litter-mediated nutrient cycling. Numerous studies have reported different effects of N addition on litter decomposition, exhibiting positive, negative, or neutral effects. Previous meta-analysis of litter decomposition under N addition was mainly based on a small number of samples to allow comparisons...
Article
High ammonia (NH3) emissions from fertilized soil in China have led to various concerns regarding environmental safety and public health. In response to China's blue skies protection campaign, effective NH3 reduction measures need to consider both mitigation efficiency and food security. In this context, we conducted a meta-analysis (including 2980...
Article
The study of emissions and depositions of atmospheric reactive nitrogen species (Nrs) in a region is important to uncover the sources and sinks of atmospheric Nrs in the region. In this study, atmospheric total Nrs depositions including both wet-only and dry deposition were monitored simultaneously across major land use types in a 105 km² catchment...
Article
Full-text available
Atmospheric reactive nitrogen (Nr) pollution leads to enhanced Nr deposition. There still big gaps in understanding atmospheric nitrogen deposition because of limited monitoring sites in arid land ecosystems of Central Asia. To determine Nr concentrations and deposition in the study area, we have set up 20 monitoring sites to collect gaseous, parti...
Article
Agroecosystems provide multiple goods and services that are important for human welfare. Despite the importance of field management practices for agroecosystem service delivery, the links of socioeconomic factors, management practices and ecosystem multifunctionality have rarely been explicitly evaluated in agroecosystems. Here we used a county-sca...
Article
Full-text available
Variations in precipitation and atmospheric N deposition affect water and N availability in desert and thus may have significant effects on desert ecosystems. Haloxylon ammodendron is a dominant plant in Asian desert, and addressing its physiological acclimatization to the changes in precipitation and N deposition can provide insight into how deser...
Article
In order to cope with heavy haze pollution in Beijing, the Air Pollution Prevention and Control Action Plan was issued in 2013. In this study, we took January observations from 2014 to 2018 as a case study to assess wintertime air quality improvement in Beijing after five years of continuous emission control measures and to investigate the causes o...
Article
Full-text available
Nitrogen (N) is an essential but generally limiting nutrient for biological systems. Development of the Haber-Bosch industrial process for ammonia synthesis helped to relieve N limitation of agricultural production, fueling the Green Revolution and reducing hunger. However, the massive use of industrial N fertilizer has doubled the N moving through...
Article
Full-text available
Limited availability of atmospheric ammonia (NH3) observations limits our understanding of controls on its spatial and temporal variability and its interactions with the ecosystem. Here we used the Model for Ozone and Related chemical Tracers version 4 (MOZART-4) global chemistry transport model and the Hemispheric Transport of Air Pollution versio...
Article
Full-text available
Aims Litter is frequently buried in the soil in alpine grasslands due to grassland degradation, serious rodent infestation, and frequent strong winds. However, the effects of various litter positions on litter decomposition rates and nutrient dynamics under nitrogen (N) enrichment in such areas remain unknown. Methods A field experiment was perfor...
Article
Full-text available
Ozone concentrations near the land surface are rising in Asia while they are declining or stagnating in Europe and North America. Ozone is the most widespread air pollutant negatively affecting vegetation, and its increased concentrations pose a major threat to food quality and production and other ecosystem services in Asia. In this review, we pro...
Article
A meta-analysis was preformed to reveal how environmental and experimental factors alter the effects of N enrichment on the concentrations and stoichiometry of N and P in both mature and senesced foliage and nutrient resorption, with published studies from Chinese grasslands. N enrichment, when averaged across the studies, significantly increased t...
Article
Full-text available
Atmospheric nitrogen (N) deposition in China has been the largest worldwide. Yet the impacts of atmospheric N deposition on soil N2O emissions were often ignored by previous studies. Thus, we investigated how N deposition affected N2O emissions over China using the process-based model (DNDC, DeNitrification-DeComposition). Total soil N inputs were...
Article
The Clean Air Action implemented by the Chinese government in 2013 has greatly improved air quality in the North China Plain (NCP). In this work, we report changes in the chemical components of atmospheric fine particulate matter (PM2.5) at four NCP sampling sites from 2012/2013 to 2017 to investigate the impacts and drivers of the Clean Air Action...
Article
Full-text available
Increased nitrogen (N) availability induced by fertilizer use, rapid urbanization, and livestock cultivation has important effects on the biogeochemical cycles of plant N and phosphorus (P). Knowledge of the long-term N enrichment effects on the biogeochemical cycling of N and P via plant ecological stoichiometry and nutrient resorption remains lim...
Article
Full-text available
To investigate the formation and evolution mechanism of haze pollution in Beijing cold days, we measured reactive nitrogen gases (e.g. NH 3 and HNO 3 ), SO 2 and major water-soluble inorganic ions of PM 2.5 simultaneously in a two-year (from November to April) study. We found that NH 3 and NO 3 ⁻ have the highest concentrations among the gaseous pr...
Article
Nitrous oxide (N2O) is an important greenhouse gas and a precursor of ozone depletion in the upper atmosphere, thus contributing to climate change and biological safety. The mechanisms and response characteristics of N2O emission in desert soils to precipitation and nitrogen (N) deposition are still unclear. To further elucidate this, an in-situ ex...
Article
Full-text available
Since the industrial revolution, it has been assumed that fossil-fuel combustions dominate increasing nitrogen oxide (NO x ) emissions. However, it remains uncertain to the actual contribution of the non-fossil fuel NO x to total NO x emissions. Natural N isotopes of NO 3 ⁻ in precipitation (δ ¹⁵ N w-NO3− ) have been widely employed for tracing atm...
Article
Full-text available
With atmospheric reactive nitrogen (Nr) emissions increasing globally, research into Nr deposition has attracted increasing attention, especially in remote environments. These ecosystems are very sensitive to global change, especially enhanced Nr deposition. Forest environments, in particular, are highlighted because of their important ecological f...
Article
Full-text available
China has the world's highest nitrogen (N) application rate, and the lowest N use efficiency (NUE). With the crop yield increasing, serious N pollution is also caused. An in-situ field experiment (2011–2015) was conducted to examine the effects of three N levels, 0 (i.e., no fertilizer N addition to soil), 120, and 180 kg N ha⁻¹ using integrated ri...
Article
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The hilly area of Southwest China is a typical rice production area which is limited by seasonal droughts and low temperature in the early rice growth period. A field experiment was conducted on three typical paddy fields (low-lying paddy field, medium-elevation paddy field, and upland paddy field) in this region. Nitrogen (N) treatment (180 kg N h...
Article
Arbuscular mycorrhizal fungi (AMF) can significantly influence the soil carbon cycle, however, their impacts on desert soils are still unclear. Here, a field control experiment, using in‐growth mesocosms, was conducted to quantitatively assess the contribution of AMF and ephemeral plants to ecosystem respiration (Re) and methane (CH4) flux in the G...
Article
Full-text available
This study investigates the concentrations and δ¹⁵N values of NH3 in Beijing during and after the 2020 COVID-19 lockdown. Higher NH3 concentrations and lower δ¹⁵N-NH3(measured) were observed at most sites in 2020 compared to 2017. Except for a site inside a tunnel, NH3 concentrations did not increase significantly after the lockdown had ended compa...
Article
Full-text available
China has experienced a dramatic change in atmospheric reactive nitrogen (Nr) emissions over the past four decades. However, it remains unclear how nitrogen (N) deposition has responded to increases and/or decreases in Nr emissions. This study quantitatively assesses temporal and spatial variations in measurements of bulk and calculated dry N depos...
Article
Atmospheric reactive nitrogen (Nr) has been a cause of serious environmental pollution in China. Historically, China used too little Nr in its agriculture to feed its population. However, with the rapid increase in N fertilizer use for food production and fossil fuel consumption for energy supply over the last four decades, increasing gaseous Nr sp...
Preprint
Full-text available
Variations in precipitation and atmospheric N deposition affect water and N availability in desert, and thus may have significant effects on desert ecosystems. Haloxylon ammodendron is a dominant plant in Asian desert, and addressing its physiological acclimatization to the changes in precipitation and N deposition can provide an insight into how d...