What is the pollution limit? Comparing nutrient loads with thresholds to improve water quality in Lake Baiyangdian.

Ecological thresholds are useful indicators for water quality managers to define limits to nutrient pollution. A common approach to estimating ecological thresholds is using critical nutrient loads. Critical nutrient loads are typically defined as the loads at which the phytoplankton chlorophyll-a exceeds a certain concentration.

Food and feed trade has greatly impacted global land and nitrogen use efficiencies over 1961-2017.

International trade of agricultural products has complicated and far-reaching impacts on land and nitrogen use efficiencies. We analysed the productivity of cropland and livestock and associated use of feed and fertilizer efficiency for over 240 countries, and estimated these countries' cumulative contributions to imports and exports of 190 agricultural products for the period 1961-2017. Crop trade has increased global land and partial fertilizer nitrogen productivities in terms of protein production, which equalled savings of 2,270 Mha cropland and 480 Tg synthetic fertilizer nitrogen over the analysed period.

Long-term warming and nitrogen fertilization affect C-, N- and P-acquiring hydrolase and oxidase activities in winter wheat monocropping soil.

The enzymatic activities and ratios are critical indicators for organic matter decomposition and provide potentially positive feedback to carbon (C) loss under global warming. For agricultural soils under climate change, the effect of long-term warming on the activities of oxidases and hydrolases targeting C, nitrogen (N) and phosphorus (P) and their ratios is unclear, as well as whether and to what extend the response is modulated by long-term fertilization. A 9-year field experiment in the North China Plain, including an untreated control, warming, N fertilization, and combined (WN) treatment plots, compared the factorial effect of warming and fertilization.

Nitrifier denitrification dominates nitrous oxide production in composting and can be inhibited by a bioelectrochemical nitrification inhibitor.

Targeted options to reduce nitrous oxide (NO) emission from composting is scarce due to challenges in disentangling the complex NO production pathways. Here, combined approaches of nitrogen form analysis, isotopocule mapping, quantitative PCR, and Illumina MiSeq sequencing were used to differentiate NO production pathways and decipher the underlying biochemical mechanisms. Results suggested that most NO was produced at the latter stage through nitrifier denitrification.

Strategies to reduce ammonia emissions from livestock and their cost-benefit analysis: A case study of Sheyang county.

Ammonia (NH) emissions, the majority of which arise from livestock production, are linked to high concentration of PM and lower air quality in China. NH mitigation options were well studied at the small-scale (laboratory or pilot), however, they lack of a large-scale test in China. This study fills this crucial gap by evaluating the cost-benefit of pioneering NH mitigation projects carried out for a whole county - Sheyang, Jiangsu province, China.

Characterization of tetracycline-resistant microbiome in soil-plant systems by combination of HO-based DNA-Stable isotope probing and metagenomics.

The emergence and spread of antibiotic resistance have been considered as a global health threat. However, effective methods to identify antibiotic-resistant bacteria (ARB) in complex microbial community are lacking, and the potential transmission pathways of ARB and antibiotic resistance genes (ARGs) in the soil-plant system remain scarce. Here in this study, tetracycline was chosen as the target antibiotic due to its globally wide usage and clinical significance.

Model-based analysis of phosphorus flows in the food chain at county level in China and options for reducing the losses towards green development.

Insight in the phosphorus (P) flows and P balances in the food chain is largely unknown at county scale in China, being the most appropriate spatial unit for nutrient management advice. Here, we examined changes in P flows in the food chain in a typical agricultural county (Quzhou) during 1980-2017, using substance flow analyses. Our results show that external P inputs to the county by feed import and fertilizer were 7 times greater in 2017 than in 1980, resulting in a 7-fold increase in P losses to the environment in the last 3 decades, with the biggest source being animal production.

Nitrogen budgets of contrasting crop-livestock systems in China.

The crop-livestock system is responsible for a large proportion of global reactive nitrogen (Nr) losses, especially from China. There are diverse livestock systems with contrasting differences in feed, livestock and manure management. However, it is not yet well understood which factors greatly impact on the nitrogen (N) budgets and losses of each system.

Atmospheric nitrogen deposition: A review of quantification methods and its spatial pattern derived from the global monitoring networks.

Atmospheric nitrogen (N) deposition is a vital component of the global N cycle. Excessive N deposition on the Earth's surface has adverse impacts on ecosystems and humans. Quantification of atmospheric N deposition is indispensable for assessing and addressing N deposition-induced environmental issues.

An electric field immobilizes heavy metals through promoting combination with humic substances during composting.

The aim of this study was to explore a novel method to immobilize heavy metals (HM) in composting through increasing the combination of these with humic substances. An electric-field assistant technique was applied to strengthen biomass biodegradation and assess the impact on the humification process and HM immobilization in composting. Results demonstrated that the application of an electric field enriched bacterial abundance and enhanced bacterial metabolism.

Equality in river pollution control in China.

Water pollution is a serious problem in China. This study focuses on equality in pollution control in the Yangtze, Yellow and Pearl. We first quantified environmental targets for nitrogen (N) and phosphorus (P) at the river mouth.

Soil Microbial Composition and Gene Abundance Are Sensitive to Phosphorus Level in a Long-Term Wheat-Maize Crop System.

Microbes associated with phosphorus (P) cycling are intrinsic to soil P transformation and availability for plant use but are also influenced by the application of P fertilizer. Nevertheless, the variability in soil P in the field means that integrative analyses of soil P cycling, microbial composition, and microbial functional genes related to P cycling remain very challenging. In the present study in the North China Plain, we subjected the bacterial and fungal communities to amplicon sequencing analysis and characterized the alkaline phosphatase ( encoding bacterial alkaline phosphatase in a long-term field experiment (10 years) with six mineral P fertilization rates up to 200 kg P ha.

Improved Estimates of Ammonia Emissions from Global Croplands.

Reducing ammonia (NH) volatilization from croplands while satisfying the food demand is strategically required to mitigate haze pollution. However, the global pattern of NH volatilization remains uncertain, primarily because of the episodic nature of NH volatilization rates and the high variation of fertilization practices. Here, we improve a global estimate of crop-specific NH emissions at a high spatial resolution using an updated data-driven model with a survey-based dataset of the fertilization scheme.

Combined applications of organic and synthetic nitrogen fertilizers for improving crop yield and reducing reactive nitrogen losses from China's vegetable systems: A meta-analysis.

The combined application of organic and synthetic nitrogen (N) fertilizers is being widely recommended in China's vegetable systems to reduce reliance on synthetic N fertilizer. However, the effect of substituting synthetic fertilizer with organic fertilizer on vegetable productivity (yield, N uptake and nitrogen use efficiency) and reactive nitrogen (Nr) losses (NO emission, N leaching and NH volatilization) remains unclear. A meta-analysis was performed using peer-reviewed papers published from 2000 to 2019 to comprehensively assess the effects of combined application of organic and synthetic N fertilizers.

Air quality, nitrogen use efficiency and food security in China are improved by cost-effective agricultural nitrogen management.

China's gains in food production over the past four decades have been associated with substantial agricultural nitrogen losses, which contribute to air and water pollution, greenhouse gas emissions and damage to human health. Here, we explore the potential to improve agricultural production practices that simultaneously increase yields while addressing these environmental challenges. We link agronomic research with air quality modelling for an integrated assessment of four improved nitrogen management strategies: improved farm management practices with nitrogen use reductions; machine deep placement of fertilizer; enhanced-efficiency fertilizer use; and improved manure management.

Ammonia emissions from different pig production scales and their temporal variations in the North China Plain.

Pig production systems in China are shifting from small to industrial scale. Significant variation in housing ammonia (NH) emissions can exist due to differences in diet, housing design, and management practices. However, there is a knowledge gap regarding the impacts of farm-scale in China, which may be critical in identifying hotspots and mitigation targets.

Beyond Plant Microbiome Composition: Exploiting Microbial Functions and Plant Traits via Integrated Approaches.

Plants recruit specific microorganisms to live inside and outside their roots that provide essential functions for plant growth and health. The study of the microbial communities living in close association with plants helps in understanding the mechanisms involved in these beneficial interactions. Currently, most of the research in this field has been focusing on the description of the taxonomic composition of the microbiome.

Spatial Planning Needed to Drastically Reduce Nitrogen and Phosphorus Surpluses in China's Agriculture.

China's fertilization practices contribute greatly to the global biogeochemical nitrogen (N) and phosphorus (P) flows, which have exceeded the safe-operating space. Here, we quantified the potentials of improved nutrient management in the food chain and spatial planning of livestock farms on nutrient use efficiency and losses in China, using a nutrient flow model and detailed information on >2300 counties. Annual fertilizer use could be reduced by 26 Tg N and 6.

Plant community composition steers grassland vegetation via soil legacy effects.

Soil legacy effects are commonly highlighted as drivers of plant community dynamics and species co-existence. However, experimental evidence for soil legacy effects of conditioning plant communities on responding plant communities under natural conditions is lacking. We conditioned 192 grassland plots using six different plant communities with different ratios of grasses and forbs and for different durations.

Acidification of manure reduces gaseous emissions and nutrient losses from subsequent composting process.

Manure acidification is recommended to minimize ammonia (NH) emission at storage. However, the potential for acidification to mitigate NH emission from storage and the impact of manure acidification (pH range 5-8) on composting have been poorly studied. The effects of manure acidification at storage on the subsequent composting process, nutrient balance, gaseous emissions and product quality were assessed through an analysis of literature data and an experiment under controlled conditions.

Effective removal of antibiotic resistance genes and potential links with archaeal communities during vacuum-type composting and positive-pressure composting.

As a major reservoir of antibiotics, animal manure contributes a lot to the augmented environmental pressure of antibiotic resistance genes (ARGs). This might be the first study to explore the effects of different ventilation types on the control of ARGs and to identify the relationships between archaeal communities and ARGs during the composting of dairy manure. Several ARGs were quantified via Real-time qPCR and microbial communities including bacteria and archaea were analyzed by High-throughput sequencing during vacuum-type composting (VTC) and positive-pressure composting (PPC).

Composting process and odor emission varied in windrow and trough composting system under different air humidity conditions.

To comprehensively investigate the effect of different air humidity conditions on the performance and odor emission in composting technology, a full-scale experiment was conducted simultaneously in the regions with low air relative humidity (Kunming) and high relative air humidity (Xishuangbanna), Yunnan province. The results showed that: In the regions with low relative air humidity, similar performances were found on organic matter degradation and germination index values in windrow and trough composting. Windrow composting got lower HS emission, but higher NH release comparing with trough composting.

How to avoid coastal eutrophication - a back-casting study for the North China Plain.

Eutrophication is a serious problem in Chinese seas. We explore possibilities to avoid coastal eutrophication without compromising food production in the North China Plain. We used the Model to Assess River Inputs of Nutrient to seAs (MARINA 1.

Reducing Ammonia Emissions from Dairy Cattle Production via Cost-Effective Manure Management Techniques in China.

This study analyzed ammonia reduction potential and related costs and benefits of several ammonia emission reduction technologies applicable for dairy production from cattle in China. Specifically, these included diet manipulation, manure acidification, manure/slurry covers, and solid manure compaction. Ammonia emissions for China were estimated using the GAINS and NUFER models, while mitigation potentials of technologies were determined from laboratory studies.