Nitrogen Surplus Benchmarks for Controlling N Pollution in the Main Cropping Systems of China

This study was financially supported by National Key Research and Development Project of China (2017YFD0200105), China−UK PhD Placement Programme funded by CSC (201603780082), and contributes to “N-Circle” and “CINAg” projects funded by the Newton Fund via UK BBSRC/NERC (grants BB/N013484/1 and BB/N013468/1, respectively).Peer reviewedPostprintPostprin

Enhanced-efficiency fertilizers are not a panacea for resolving the nitrogen problem

Abstract Improving nitrogen (N) management for greater agricultural output while minimizing unintended environmental consequences is critical in the endeavor of feeding the growing population sustainably amid climate change. Enhanced-efficiency fertilizers (EEFs) have been developed to better synchronize fertilizer N release with crop uptake, offering the potential for enhanced N use efficiency (NUE) and reduced losses. Can EEFs play a significant role in helping address the N management challenge? Here we present a comprehensive analysis of worldwide studies published in 1980–2016 evaluating four major types of EEFs (polymer-coated fertilizers PCF, nitrification inhibitors NI, urease inhibitors UI, and double inhibitors DI, i.e. urease and nitrification inhibitors combined) regarding their effectiveness in increasing yield and NUE and reducing N losses. Overall productivity and environmental efficacy depended on the combination of EEF type and cropping systems, further affected by biophysical conditions. Best scenarios include: (i) DI used in grassland (n = 133), averaging 11% yield increase, 33% NUE improvement, and 47% decrease in aggregated N loss (sum of NO3-, NH3, and N2O, totaling 84 kg N/ha); (ii) UI in rice-paddy systems (n = 100), with 9% yield increase, 29% NUE improvement, and 41% N-loss reduction (16 kg N/ha). EEF efficacies in wheat and maize systems were more complicated and generally less effective. In-depth analysis indicated that the potential benefits of EEFs might be best achieved when a need is created, for example, by downward adjusting N application from conventional rate. We conclude that EEFs can play a significant role in sustainable agricultural production but their prudent use requires firstly eliminating any fertilizer mismanagement plus the implementation of knowledge-based N management practices

The European Nitrogen Problem in a Global Perspective

Nature of the problem (science/management/policy): Reactive nitrogen has both positive and negative effects on ecosystem and human health. Reactive nitrogen is formed through the use of fossil fuels releasing large amounts of nitrogen oxides into the atmosphere and through the production of ammonia by the Haber-Bosch process and using it in agriculture to increase our food, feed and fuel production. While the use of nitrogen as a fertilizer has brought enormous benefits, losses of fertilizer nitrogen and combustion nitrogen to the environment lead to many side effects on human health, ecosystem health, biodiversity and climate. Approaches: The European nitrogen problem is placed in a global perspective, showing the European nitrogen fixation, transport and environmental impacts compared to different regions of the globe. Key findings/state of knowledge: An overview is provided of the nitrogen issues and challenges in Europe and places them in a broader global context. Europe is one of the leading producers of reactive nitrogen, but it is also the first region in the world where the issue was recognized and in some parts of Europe the reactive nitrogen losses to the environment started to decrease. There is a clear policy on reducing nitrogen oxide emissions that led to reductions by implementation of end of pipe technology. Fertilizer production and use decreased in Europe in the early 1990s, in particular, due to the economic recession in the Eastern part of Europe. Currently, the fertilizer use in EU25 is about 12 Mton, which is 4 Mton lower than in the 1980s and gradually increasing. The nitrogen use efficiency of nitrogen in the EU, defined as the net output of N in products divided by the net input is about 36%. This is lower than the world average (50%) as fertilization rates are much higher. Major uncertainties/challenges: The effects related to losses of nitrogen in Europe include the exceedance of critical loads and the resulting biodiversity loss, ground water pollution and eutrophication of ecosystems; eutrophication of open waters and coastal areas resulting in algae blooms and fish kills; increased levels of NOx and aerosols in the atmosphere resulting in human health impacts and climate change; and the increased emissions of the greenhouse gas nitrous oxide resulting in climate change. Nitrogen also affects the biogeochemical cycles of other components such as carbon. Recommendations (research/policy): The complexity of multi-pollutant ¿ multiple-effect interactions is a major hurdle to improving public awareness.JRC.H.1-Water Resource

Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration

This work was funded by National Basic Research Program of China (2014CB953800), Young Talents Projects of the Institute of Urban Environment, Chinese Academy of Sciences (IUEMS201402), National Natural Science Foundation of China (41471190, 41301237, 71704171), China Postdoctoral Science Foundation (2014T70144) and Discovery Early Career Researcher Award of the Australian Research Council (DE170100423). The work contributes to the UK-China Virtual Joint Centres on Nitrogen “N-Circle” and “CINAg” funded by the Newton Fund via UK BBSRC/NERC (grants BB/N013484/1 and BB/N013468/1, respectively).Peer reviewedPostprintPostprin

Milling plant and soil material in plastic tubes over-estimates carbon and under-estimates nitrogen concentrations

Peer reviewedPostprin

Low DHEAS: A Sensitive and Specific Test for the Detection of Subclinical Hypercortisolism in Adrenal Incidentalomas.

CONTEXT: Subclinical hypercortisolism (SH) occurs in 5% to 30% of adrenal incidentalomas (AIs). Common screening tests for adrenocorticotropin-independent hypercortisolism have substantial false-positive rates, mandating further time and resource-intensive investigations. OBJECTIVE: To determine whether low basal dehydroepiandrosterone sulfate (DHEAS) is a sensitive and specific screening test for SH in AI. SETTING AND PATIENTS: In total, 185 patients with AI were screened for adrenal medullary (plasma metanephrines) and cortical [1 mg overnight dexamethasone suppression test (ONDST), 24-hour urinary free cortisol (UFC), serum DHEAS, plasma renin, and aldosterone] hyperfunction. Positive ONDST [≥1.8 mcg/dL (≥50 nmol/L)] and/or UFC (more than the upper limit of reference range) results were further investigated. We diagnosed SH when at least 2 of the following were met: raised UFC, raised midnight serum cortisol, 48-hour dexamethasone suppression test (DST) cortisol ≥1.8 mcg/dL (≥50 nmol/L). RESULTS: 29 patients (16%) were diagnosed with SH. Adrenocorticotropin was 99%) and specific (91.9%) for the diagnosis of SH. Cortisol following 1 mg ONDST of 1.9 mcg/dL (53 nmol/L) was a sensitive (>99%) screening test for SH but had lower specificity (82.9%). The 24-hour UFC lacked sensitivity (69%) and specificity (72%). CONCLUSION: A single basal measurement of DHEAS offers comparable sensitivity and greater specificity to the existing gold-standard 1 mg DST for the detection of SH in patients with AIs

11 C-Metomidate PET/CT is a useful adjunct for lateralization of primary aldosteronism in routine clinical practice.

OBJECTIVE: To describe clinical practice experience of 11 C-Metomidate PET/CT as an adjunct to adrenal vein sampling (AVS) in the lateralization of aldosterone-producing adenomas (APA) in primary aldosteronism (PA). CONTEXT: Accurate lateralization of APA in the setting of PA offers the potential for surgical cure and improved long-term cardiovascular outcomes. Challenges associated with AVS, the current gold standard lateralization modality, mean that only a small proportion of potentially eligible patients currently make it through to surgery. This has prompted consideration of alternative strategies for lateralization, including the application of novel molecular PET tracers such as 11 C-Metomidate. DESIGN: Clinical Service Evaluation/Retrospective audit. PATIENTS: Fifteen individuals with a confirmed diagnosis of PA, undergoing lateralization with 11 C-Metomidate PET/CT prior to final clinical decision on surgical vs medical management. MEASUREMENTS: All patients underwent screening aldosterone renin ratio (ARR), followed by confirmatory testing with the seated saline infusion test, according to Endocrine Society Clinical Practice Guidelines. Adrenal glands were imaged using dedicated adrenal CT. 11 C-Metomidate PET/CT was undertaken due to equivocal or failed AVS. Management outcomes were assessed by longitudinal measurement of blood pressure, ARR, number of hypertensive medications following adrenalectomy or institution of medical therapy. RESULTS: We describe the individual lateralization and clinical outcomes for 15 patients with PA. CONCLUSION: 11 C-Metomidate PET/CT in conjunction with adrenal CT and AVS provided useful information which aided clinical decision-making for PA within a multidisciplinary hypertension clinic

Progress on improving Agricultural Nitrogen use efficiency: UK-China viortual joint centers on Nitrogen Agronomy

Two virtual joint centers for nitrogen agronomy were established between the UK and China to facilitate collaborative research aimed at improving nitrogen use efficiency (NUE) in agricultural production systems and reducing losses of reactive N to the environment. Major focus areas were improving fertilizer NUE, use of livestock manures, soil health, and policy development and knowledge exchange. Improvements to fertilizer NUE included attention to application rate in the context of yield potential and economic considerations and the potential of improved practices including enhanced efficiency fertilizers, plastic film mulching and cropping design. Improved utilization of livestock manures requires knowledge of the available nutrient content, appropriate manure processing technologies and integrated nutrient management practices. Soil carbon, acidification and biodiversity were considered as important aspects of soil health. Both centers identified a range of potential actions that could be taken to improve N management, and the research conducted has highlighted the importance of developing a systemslevel approach to assessing improvement in the overall efficiency of N management and avoiding unintended secondary effects from individual interventions. Within this context, the management of fertilizer emissions and livestock manure at the farm and regional scales appear to be particularly important targets for mitigation

Multiseason recoveries of organic and inorganic nitrogen-15 in tropical cropping systems

In tropical agroecosystems, limited N availability remains a major impediment to increasing yield. A 15N-recovery experiment was conducted in 13 diverse tropical agroecosystems. The objectives were to determine the total recovery of one single 15N application of inorganic or organic N during three to six growing seasons and to establish whether the losses of N are governed by universal principles. Between 7 and 58% (average of 21%) of crop N uptake duringthe first growing season was derived from fertilizer. On average, 79% of crop N was derived from the soil. When 15N-labeled residues were applied, in the first growing season 4% of crop N was derived from the residues. Average recoveries of 15N- labeled fertilizer and residue in crops after the first growing season were 33 and 7%, respectively. Corresponding recoveries in the soil were 38 and 71 %. An additional 6% of the fertilizer and 9.1 % of the residue was recovered by crops during subsequent growing seasons. There were no significant differences in total 15N recovery (average 54%) between N from fertilizer and N from residue. After five growing seasons, more residue N (40%) than fertilizer N (18%) was recovered in the soil, better sustaining the soil organic matter N content. Long-term total recoveries of 15N-labeled fertilizer or residue in the crop and soil were similar. Soil N remained the primary source of N for crops. As higher rainfall and temperature tend to cause higher N losses, management practices to improve N use efficiency and reduce losses in wet tropical regions will remain a challenge