Acidification of European croplands by nitrogen fertilization: Consequences for carbonate losses, and soil health

Soil acidification is an ongoing problem in intensively cultivated croplands due to inefficient and excessive nitrogen (N) fertilization. We collected high-resolution data comprising 19,969 topsoil (0-20 cm) samples from the Land Use and Coverage Area frame Survey (LUCAS) of the European commission in 2009 to assess the impact of N fertilization on buffering substances such as carbonates and base cations. We have only considered the impacts of mineral fertilizers from the total added N, and a N use efficiency of 60 %. Nitrogen fertilization adds annually 6.1 × 107 kmol H+ to European croplands, leading to annual loss of 6.1 × 109 kg CaCO3. Assuming similar acidification during the next 50 years, soil carbonates will be completely removed from 3.4 × 106 ha of European croplands. In carbonate-free soils, annual loss of 2.1 × 107 kmol of basic cations will lead to strong acidification of at least 2.6 million ha of European croplands within the next 50 years. Inorganic carbon and basic cation losses at such rapid scale tremendously drop the nutrient status and production potential of croplands. Soil liming to ameliorate acidity increases pH only temporarily and with additional financial and environmental costs. Only the direct loss of soil carbonate stocks and compensation of carbonate-related CO2 correspond to about 1.5 % of the proposed budget of the European commission for 2023. Thus, controlling and decreasing soil acidification is crucial to avoid degradation of agricultural soils, which can be done by adopting best management practices and increasing nutrient use efficiency. Regular screening or monitoring of carbonate and base cations contents, especially for soils, where the carbonate stocks are at critical levels, are urgently necessary.

Measuring the effectiveness of an integrated intervention package to improve the level of infection prevention and control: a multi-centre study in Bangladesh

BACKGROUND

Infection prevention and control (IPC) is a critical component of delivering safe, effective and high-quality healthcare services, and eliminating avoidable healthcare-associated infections (HAIs) in health facilities, predominantly in population-dense settings such as Bangladesh.

AIM

Our study aimed to assess the effect of an integrated intervention package in improving the IPC level of the health facilities in Bangladesh.

METHODS

We conducted a pre-post intervention study in six district hospitals (DHs) and 13 Upazila Health Complexes (UHCs) in the six districts of Bangladesh. Baseline and endline assessments were conducted between March and December 2021 using the adapted World Health Organization Infection Prevention and Control Assessment Framework (WHO-IPCAF) tool. The IPCAF score, ranging from 0-800, was calculated by adding the scores of eight components, and the IPC promotion and practice level was categorized as Inadequate (0-200), Basic (201-400), Intermediate (401-600) and Advanced (601-800). The integrated intervention package including IPC committee formation, healthcare provider training, logistics provision, necessary guidelines distribution, triage/flu corners establishment, and infrastructure development was implemented in all facilities.

RESULTS

The average IPCAF score across all the facilities showed a significant increase from 16% (95% CI: 11.5-20.65%) to 54% (95% CI: 51.4-57.1%). Overall, the IPCAF score increased by 34 percentage points (P<0.001) in DHs and 40 percentage points (P<0.001) in UHCs. Following the intervention, 12 (three DHs, nine UHCs) of 19 facilities progressed from inadequate to intermediate, and another three DHs upgraded from basic to intermediate in terms of IPC level.

CONCLUSION

The integrated intervention package improved IPCAF score in all facilities.

Inorganic carbon is overlooked in global soil carbon research: A bibliometric analysis

Soils are a major player in the global carbon (C) cycle and climate change by functioning as a sink or a source of atmospheric carbon dioxide (CO2). The largest terrestrial C reservoir in soils comprises two main pools: organic (SOC) and inorganic C (SIC), each having distinct fates and functions but with a large disparity in global research attention. This study quantified global soil C research trends and the proportional focus on SOC and SIC pools based on a bibliometric analysis and raise the importance of SIC pools fully underrepresented in research, applications, and modeling. Studies on soil C pools started in 1905 and has produced over 47,000 publications (>1.7 million citations). Although the global C stocks down to 2 m depth are nearly the same for SOC and SIC, the research has dominantly examined SOC (>96 % of publications and citations) with a minimal share on SIC (<4%). Approximately 40 % of the soil C research was related to climate change. Despite poor coverage and publications, the climate change-related research impact (citations per document) of SIC studies was higher than that of SOC. Mineral associated organic carbon, machine learning, soil health, and biochar were the recent top trend topics for SOC research (2020-2023), whereas digital soil mapping, soil properties, soil acidification, and calcite were recent top trend topics for SIC. SOC research was contributed by 151 countries compared to 88 for SIC. As assessed by publications, soil C research was mainly concentrated in a few countries, with only 9 countries accounting for 70 % of the research. China and the USA were the major producers (45 %), collaborators (37 %), and funders of soil C research. SIC is a long-lived soil C pool with a turnover rate (leaching and recrystallization) of more than 1000 years in natural ecosystems, but intensive agricultural practices have accelerated SIC losses, making SIC an important player in global C cycle and climate change. The lack of attention and investment towards SIC research could jeopardize the ongoing efforts to mitigate climate change impacts to meet the 1.5-2.0 °C targets under the Paris Climate Agreement of 2015. This bibliographic study calls to expand the research focus on SIC and including SIC fluxes in C budgets and models, without which the representation of the global C cycle is incomplete.

A Comparison of Microwave Ablation and Cryoablation for the Treatment of Renal Cell Carcinoma: A Systematic Literature Review and Meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis comparing microwave ablation (MWA) and cryoablation for renal cell carcinoma (RCC).

METHODS

The systematic search was performed in MEDLINE, Embase, and Cochrane databases. Studies published in English from January 2006 to February 2022 that assessed adults with primary RCC who received MWA or cryoablation were included. Study arms from RCTs, comparative observational, and single-arm studies were eligible. The outcomes included local tumor recurrence (LTR), overall survival, disease-free survival, overall/major complications, procedure/ablation time, 1- to 3-month primary technique efficacy, and technical success. Single-arm meta-analyses were performed using the random effects model. Sensitivity analyses excluding low-quality studies assessed using the MINORs scale were performed. Univariable and multivariable examined the effects of prognostic factors.

RESULTS

Baseline characteristics were similar between groups and mean tumor size for MWA and cryoablation were 2.74 and 2.69 cm. Single-arm meta-analyses were similar for LTR and secondary outcomes between cryoablation and MWA. Ablation time was significantly shorter with MWA than with cryoablation (meta-regression weighted mean difference 24.55 minutes, 95% confidence interval -31.71, -17.38, P < .0001). One-year LTR was significantly lower with MWA than cryoablation (odds ratio 0.33, 95% confidence interval 0.10-0.93, P = .04). There were no significant differences for other outcomes.

CONCLUSION

MWA provides significantly improved 1-year LTR and ablation time compared with cryoablation for patients with RCC. Other outcomes appeared similar or favorable for MWA; however, results were not statistically significant. MWA of primary RCC is as safe and effective as cryoablation, which should be confirmed with future comparative studies.

1362 ANTICHOLINERGIC PRESCRIBING HABITS AND ITS ASSOCIATIONS IN A COMMUNITY POPULATION OF PEOPLE LIVING WITH DEMENTIA

Introduction

Many commonly prescribed medications have inadvertent anticholinergic effects. People with Dementia (PwD) are more vulnerable to these effects and at risk of adverse outcomes, the risk being higher with a greater degree of anticholinergic exposure. We investigated prescribing patterns and Anticholinergic burden (ACB) in a cohort of community-dwelling older adults with dementia and aimed to explore the effect of ACB on cognition, mood, and quality of life(QoL).

Method

The medication and demographic information for 87 (39 female) community-dwelling PwD were obtained from Electronic Care Summaries. We used the German Anticholinergic Burden Scale (GABS) to measure ACB. Additionally, we investigated associations between ACB and cognitive (ADAS-Cog), functional (BADL) and QoL (DemQoL) assessments.

Results

28.7% of participants had a clinically significant score (ACB&gt; 2). The most commonly prescribed medications with ACB were Lansoprazole(18.3%), Mirtazapine(12.6%) and Codeine(12.6%). ACB was higher in males and negatively correlated with age, r(87)=-.21,p=.03. There was no association between ACB and cognition, QoL, functional independence, and neuropsychiatric symptoms. Over six months, PLWD with no ACB had a greater negative change in neuropsychiatric symptoms[t(18)=2.27,p=.04] and functional independence[t(23)=-3.8,p=.001], indicating greater dependence and worsening neuropsychiatric symptoms.

Conclusion

A third of PLWD in the community had clinically significant ACB. No ACB was associated with worsening neuropsychiatric symptoms and functional dependence over a six-month period. Community prescribers should consider regular medication reviews with PLWD and carers to ensure medications are prescribed safely and appropriately.

Vulnerability and driving factors of soil inorganic carbon stocks in Chinese croplands

The long-term stability of soil inorganic carbon (SIC) and its minimum contribution towards global C cycle has been challenged, as recent studies have showed rapid decreases in SIC stocks in intensive agricultural systems. However, the extent of SIC losses and its driving factors remains unclear. Here, we compared changes in SIC density (SICD) in Chinese croplands between the 1980s and 2010s. The SIC contents in 1980s were obtained from second national soil survey (n = 949) and published studies (n = 47). The SIC contents in 2010s were based on resampling of soil profiles from the same locations during 2019 and 2020 (n = 30), as well as data from published studies and national soil survey (n = 903). We found that Chinese croplands have lost 27-38% of SICD from the 0-40 cm soil layer and that the soil pH has decreased by 0.53 units over the past 30 years. These SIC losses increased with the ratio of precipitation (P) to potential evapotranspiration (PET) and most notably with nitrogen (N) fertilization. The SICD decreased greatly in humid and semiarid regions, and these losses were enhanced by high N fertilization rates; however, the SICD increased in very arid regions. This analysis demonstrates that the water balance and N fertilization are major drivers leading to dramatic losses of SICD in croplands and, consequently, to decreases in soil fertility and functions.

Lung Function Monitoring After Lung Transplantation and Allogeneic Hematopoietic Stem Cell Transplantation

PURPOSE

Bronchiolitis obliterans syndrome (BOS) is a major cause of morbidity and mortality in lung transplantation and allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Clinical guidelines recommend lung function monitoring to aid early identification of BOS, but real-world rates of pulmonary function testing (PFT) have not been studied. The purpose of this study was to quantify PFT rates in lung transplantation and allo-HSCT recipients.

METHODS

This longitudinal retrospective study used US data from the IQVIA PharMetrics Plus commercial claims database (January 1, 2006-September 30, 2018) and the Medicare Limited Data Set (January 1, 2010-December 31, 2018). Study recipients had no evidence of transplantation 12 months before transplantation, which was identified by using diagnosis and procedure codes. PFTs were identified by using procedure codes. Outcomes were percentage of recipients who received ≥1 PFT in each follow-up year, including spirometry, lung diffusion capacity, lung function volume test, and plethysmography, including the average number of total and specific tests per recipient.

FINDINGS

The study identified 367 commercially insured and 1776 Medicare recipients who underwent lung transplantation; 92% and 86% received ≥1 lung function test in the first year after transplantation, respectively. Among recipients observable 3 years after transplant, 85% and 83% received ≥1 PFT. Among 2187 commercially insured and 1864 Medicare recipients who underwent allo-HSCT, 44% and 36% received ≥1 lung function test in the first posttransplant year. In the third year after transplant, only 31% and 26% of observable allo-HSCT recipients underwent any PFT.

IMPLICATIONS

Morbidity and mortality from BOS remain high in lung transplant and allo-HSCT recipients, but lung function testing in the first posttransplant year is not universal, with substantially lower rates among allo-HSCT recipients. Furthermore, testing rates in all cohorts declined over time. Increased and sustained monitoring could lead to earlier detection of BOS and earlier intervention and treatment.

The impact of increasing multitarget stool DNA use among colorectal cancer screeners in a self-insured US employer population

Background: In the United States (US), colorectal cancer (CRC) is the second leading cause of cancer-related deaths. With the majority of the US population covered by employer-based health plans, employers can play a critical role in increasing CRC screening adherence, which may help avert CRC-related deaths. Therefore, it is important for self-insured employers to consider the impact of appropriate utilization of CRC screening options. Objective: To evaluate the impact of increasing multitarget stool DNA [mt-sDNA (Cologuard®)] use among CRC screeners from the perspective of a US self-insured employer. Methods:A 5-year Markov model was developed to quantify the budget impact of increasing mt-sDNA from 6% to 15% among average-risk screeners using colonoscopy, fecal immunological test, and mt-sDNA. Data on direct medical costs were obtained from published literature, Medicare CPT codes, and the Healthcare cost and Utilization project. Indirect costs included productivity loss due to workplace absenteeism for CRC screening and treatment. Results: With a hypothetical population of 100,000 employees with screeners aged 50-64 years, compared to status quo, increased mt-sDNA utilization resulted in no differences in the numbers of cancers detected and the overall direct and indirect cost savings were ~$214,000 ($0.04 per-employee-per-month) over 5 years. Most of the savings were due to a reduction in the direct medical expenditure related to CRC screening, adverse events, and productivity loss due to colonoscopy screening. Similar results were observed in the model simulation among screeners aged 45-64 years. Conclusion: Increased utilization of mt-sDNA for CRC screening averts direct and indirect medical costs from a self-insured US employer perspective.

Home health care after discharge is associated with lower readmission rates for patients with acute myocardial infarction

OBJECTIVE

We studied the utilization of home health care (HHC) among acute myocardial infarction (AMI) patients, impact of HHC on and predictors of 30-day readmission.

METHODS

We queried the National Readmission Database (NRD) from 2012 to 2014identify patients with AMI discharged home with (HHC+) and without HHC (HHC-). Linkage provided in the data identified patients who had 30-day readmission, our primary end-point. The probability for each patient to receive HHC was calculated by a multivariable logistic regression. Average treatment of treated weights were derived from propensity scores. Weight-adjusted logistic regression was used to determine impact of HHC on readmission.

RESULTS

A total of 406 237 patients with AMI were discharged home. Patients in the HHC+ cohort (38 215 patients, 9.4%) were older (mean age 77 vs. 60 years P < 0.001), more likely women (53 vs. 26%, P < 0.001), have heart failure (5 vs. 0.5%, P < 0.001), chronic kidney disease (26 vs. 6%, P < 0.001) and diabetes (35 vs. 26%, P < 0.001). Patients readmitted within 30-days were older with higher rates of diabetes (RR = 1.4, 95% CI: 1.37-1.48) and heart failure (RR = 5.8, 95% CI: 5.5-6.2). Unadjusted 30-day readmission rates were 21 and 8% for HHC+ and HHC- patients, respectively. After adjustment, readmission was lower with HHC (21 vs. 24%, RR = 0.89, 95% CI: 0.82-0.96; P < 0.001).

CONCLUSION

In the United States, AMI patients receiving HHC are older and have more comorbidities; however, HHC was associated with a lower 30-day readmission rate.

Understanding the future research needs in Postural Orthostatic Tachycardia Syndrome (POTS): Evidence mapping the POTS adult literature

POTS is under diagnosed with an estimated prevalence of 0.2%. North American and Australian researchers, as well as patient groups have called for more research into POTS. However, there has been no comprehensive appraisal of the current POTS evidence base.

AIM

To map the POTS evidence base.

METHODS

Two reviewers systematically searched 12 databases until July 1st 2019 using the search term "Postural Tachycardia Syndrome" (n = 7280) and categorised the literature. Inclusion criteria included all adult published literature with no language restrictions. 779 papers are analysed and mapped.

RESULTS

Seven themes were identified: symptomology and quality of life 16.8% (n = 132), biomedical topics 16.5% (n = 130), co-morbidities 10.3% (n = 81), non-pharmacological management 9.8% (n = 77), aetiologies 6.9% (n = 53), pharmacological management 6.7% (n = 53), and clinical management 6.6% (n = 52). There 45 subthemes. Quality appraisal of the research studies (n = 233) evaluated design, sample size, outcome measures, data analysis and research biases. 74.8% (n = 175) were observational designs and 25.2% (n = 59) were experimental designs (16 using a randomised controlled design, 11 of which had a sample size greater than 21). 47.4% (n = 111) of studies only measured duration of effect for <1 day. 11.5% (n = 27) of studies reported outcomes using an unvalidated subjective measurement tool.

CONCLUSION

The volume of adult POTS literature is small and the validity and reliability of the research lacks rigour. The evidence map methodology provides POTS researchers with a benchmark for research thus far. This paper adds an in-depth research appraisal to the broad calls for action, highlighting the pressing need for multicentre, good quality research in POTS, to support guidelines and consensus development in the future.

Off-label Use of Direct Oral Anticoagulants in Patients Receiving Surgical Mechanical and Bioprosthetic Heart Valves

This cohort study assesses direct oral anticoagulant use in patients with surgical prosthetic heart valves in the United States and evaluates differences in preoperative and postoperative profiles in patients discharged while receiving direct oral anticoagulant vs warfarin.

Safety-net hospitals versus non-safety centers and clinical outcomes after trans-catheter aortic valve replacement

OBJECTIVE

To compare post-procedural outcomes of trans-catheter valve replacement (TAVR) among safety-net (SNH) and non-safety net hospitals (non-SNH).

BACKGROUND

SNH treat a large population of un-insured and low income patients; prior studies report worse outcome at these centers. Results of TAVR at these centers is limited.

METHODS

Adults undergoing TAVR at hospitals in the US participating in the National In-patient sample (NIS) database from January 2014 to December 2015 were included. A 1:1 propensity-matched cohort of patients operated at SNH and non-SNH institutions was analyzed, on the basis of 16 demographic and clinical co-variates. Main outcome was all-cause post-procedural mortality. Secondary outcomes included stroke, acute kidney injury and length of post-operative stay.

RESULTS

Between 2014 and 2015, 41,410 patients (mean age 80 ± 0.11 years, 46% female) underwent TAVR at 731 centers; 6,996 (16.80%) procedures were performed at SNH comprising 135/731 (18.4%) of all centers performing TAVR. SNH patients were more likely to be female (49% vs. 46%, p < .001); admitted emergently (31% vs. 21%; p < .001; at the lowest quartile for household income (25% % vs. 20%; p < .001) and from minorities (Blacks 5.9% vs. 3.9%; Hispanic 7.2% vs. 3.2%).Adjusted logistic regression was performed on 6,995 propensity-matched patient pairs. Post-procedural mortality [OR 0.99(0.98-1.007); p = .43], stroke [OR 1.009(0.99-1.02); p = .08], acute kidney injury [OR 0.99(0.96-1.01); p = .5] and overall length of stay (6.9 ± 0.1 vs. 7.1 ± 0.2 days; p = .57) were comparable in both cohorts.

CONCLUSION

Post-procedural outcomes after TAVR at SNH are comparable to national outcomes and wider adoption of TAVR at SNH may not adversely influence outcomes.

Safety-net hospitals versus non-safety centers and clinical outcomes after trans-catheter aortic valve replacement

OBJECTIVE

To compare post-procedural outcomes of trans-catheter valve replacement (TAVR) among safety-net (SNH) and non-safety net hospitals (non-SNH).

BACKGROUND

SNH treat a large population of un-insured and low income patients; prior studies report worse outcome at these centers. Results of TAVR at these centers is limited.

METHODS

Adults undergoing TAVR at hospitals in the US participating in the National In-patient sample (NIS) database from January 2014 to December 2015 were included. A 1:1 propensity-matched cohort of patients operated at SNH and non-SNH institutions was analyzed, on the basis of 16 demographic and clinical co-variates. Main outcome was all-cause post-procedural mortality. Secondary outcomes included stroke, acute kidney injury and length of post-operative stay.

RESULTS

Between 2014 and 2015, 41,410 patients (mean age 80 ± 0.11 years, 46% female) underwent TAVR at 731 centers; 6,996 (16.80%) procedures were performed at SNH comprising 135/731 (18.4%) of all centers performing TAVR. SNH patients were more likely to be female (49% vs. 46%, p < .001); admitted emergently (31% vs. 21%; p < .001; at the lowest quartile for household income (25% % vs. 20%; p < .001) and from minorities (Blacks 5.9% vs. 3.9%; Hispanic 7.2% vs. 3.2%).Adjusted logistic regression was performed on 6,995 propensity-matched patient pairs. Post-procedural mortality [OR 0.99(0.98-1.007); p = .43], stroke [OR 1.009(0.99-1.02); p = .08], acute kidney injury [OR 0.99(0.96-1.01); p = .5] and overall length of stay (6.9 ± 0.1 vs. 7.1 ± 0.2 days; p = .57) were comparable in both cohorts.

CONCLUSION

Post-procedural outcomes after TAVR at SNH are comparable to national outcomes and wider adoption of TAVR at SNH may not adversely influence outcomes.

Facts to acidification-induced carbonate losses from Chinese croplands

This letter explains the processes and mechanisms involved in the nitrogen-induced soil acidification causing substantial carbonate losses and subsequent CO2 emissions from Chinese croplands.

Disparities in the Management of Newly Diagnosed Paroxysmal Supraventricular Tachycardia for Women Versus Men in the United States

Background Information on differences in paroxysmal supraventricular tachycardia (PSVT) diagnosis, healthcare resource use, expenditures, and treatment among women versus men is limited. Methods and Results Study participants identified in the IBM MarketScan Commercial Research Databases were aged 18 to 40 years with newly diagnosed PSVT (International Classification of Diseases, Ninth Revision [ICD-9]: 427.0; International Classification of Diseases, Tenth Revision [ICD-10]: I47.1) from October 1, 2012, through September 30, 2016, observable 1 year preindex and postindex diagnosis. Study outcomes were mean annual per-patient healthcare resource use and expenditures before and after diagnosis. Among 5466 patients newly diagnosed with PSVT, most (66.9%) were women. Compared with men, women with PSVT tended to have higher rates of anxiety (13.9% versus 10.9%; P<0.01) and chronic pulmonary disease (10.9% versus 8.3%; P<0.01). Following diagnosis, mean annual per-patient expenditures increased for all patients, but were significantly lower for women ($26 922 versus $33 112; P<0.05), reflecting lower spending for services billed as a result of a PSVT diagnosis ($8471 versus $11 405; P<0.05). After diagnosis, nearly half of all patients had at least 1 emergency department visit (women versus men, 49.6% versus 44.5%; P<0.01) and more had hospital admissions (women versus men, 24.7% versus 20.0%; P<0.01). Fewer women were treated with cardiac ablation (12.6% versus 15.3%; P<0.01), and more were treated with medical therapy, including β blockers or calcium channel blockers (odds ratio, 1.15; 95% CI, 1.02-1.31). Conclusions Among patients aged 18 to 40 years, ≈2 of 3 patients diagnosed with PSVT were women. After diagnosis, spending was significantly lower for women, reflecting lower ablation rates and less spending on services with a PSVT diagnosis.

Do soil property variations affect dicyandiamide efficiency in inhibiting nitrification and minimizing carbon dioxide emissions?

Nitrification inhibitors (NIs) are used to retard the nitrification process and reduce nitrogen (N) losses. However, the effects of soil properties on NI efficacy are less clear. Moreover, the direct and indirect effects of soil property variations on NI efficiency in minimizing carbon dioxide (CO₂) emissions have not been previously studied. An incubation experiment was conducted for 40 days with two treatments, N (200 mg N-urea kg^-1) and N + dicyandiamide (DCD) (20 mg DCD kg^-1), and a control group (without the N) to investigate the response of ammonia-oxidizing bacteria (AOB) and archaea (AOA) to DCD application and the consequences for CO₂, nitrous oxide (N₂O) and ammonia (NH₃) emissions from six soils from the Loess Plateau with different properties. The nitrification process completed within 6-18 days for the N treatment and within 30->40 days for the N + DCD treatment. AOB increased significantly with N fertilizer application, while this effect was inhibited in soils when DCD was applied. AOA was not sensitive to N fertilizer and DCD application. The nitrification rate was positively correlated with the clay (p < 0.05) and SOM contents (p < 0.01); DCD was more effective in loam soil with low SOM and high soil pH. Soil pH significantly was decreased with N fertilizer application, while it increased when DCD was applied. Moreover, DCD application decreased CO₂ emissions from soils by 22%-172%; CO₂ emissions were negatively correlated with the clay and SOM contents. DCD application decreased N₂O emissions in each soil by 1.0- to 94-fold compared with those after N fertilizer application. In contrast, DCD application increased NH₃ release from soils by 59-278%. NH₃ volatilization was negatively correlated with clay (p < 0.05) and SOM (p < 0.01) contents and positively correlated with soil pH (p < 0.01). Therefore, soil texture, SOM and soil pH have significant effects on the DCD performance, nitrification process and gaseous emissions.

How much nitrogen does Africa need to feed itself by 2050?

Nitrogen (N) fertilizers are very important for global food self-sufficiency (FSS), particularly for Africa, where the N input in agriculture is very low. This is the first work which studies and calculates the amount of N fertilizer that each country in Africa needs to feed itself by 2050. In this study, we used five different scenarios of inorganic fertilizer N (IFN) use and human diets to calculate the amount of N fertilizer needed to achieve FSS in Africa by 2050 and analyze the changes in N budget; N losses and N use efficiency (NUE). These scenarios include 1) business as usual (BAU), 2) equitable diet (EqD; self-sufficiency), 3) an IFN input 20% less than the EqD (S1), 4) an IFN input 40% less than the EqD (S2), and 5) a 20% increase in IFN input relative to the EqD (S3). Under the BAU scenario, production trends continue as they have over the past five decades, including an unhealthy human diet. In the EqD scenario, the priority is to meet the local demand for both animal and plant proteins with a healthy human diet. Under the EqD scenario, increasing the total N input from 35 kg N ha^-1 yr^-1 to 181 kg N ha^-1 yr^-1 during 2016-2050 is needed to achieve FSS in Africa. This increase in N fertilizer use represents unprecedented N inputs to African terrestrial ecosystems - at least 52 Tg N yr^-1 - which would lead to inevitable increases in N losses. We also found that the NUE would decrease from 63% during 2010-2016 to 50% by 2050, whereas the total N surplus would increase from 13 kg N ha^-1 yr^-1 to 90 kg N ha^-1 yr^-1 by 2050. The estimated gaseous emissions would increase from 8 kg N ha^-1 yr^-1 to 61 kg N ha^-1 yr^-1 by 2050. Our findings conclude that, it is very important to consider the high N losses in Africa if the EqD scenario is applied. The S1 and S2 scenarios result in much less environmental N loss, and better NUE compared with the EqD scenario. Therefore, based on these findings we can recommend the implementation of the S2 scenario with an IFN dose of 77 kg N ha^-1 yr^-1, in parallel with the use of modern agricultural techniques and the increased use of organic inputs.

Dramatic loss of inorganic carbon by nitrogen-induced soil acidification in Chinese croplands

Intensive crop production systems worldwide, particularly in China, rely heavily on nitrogen (N) fertilization, but left more than 50% of fertilizer N in the environment. Nitrogen (over) fertilization and atmospheric N deposition induce soil acidification, which is neutralized by soil inorganic carbon (SIC; carbonates), and carbon dioxide (CO₂ ) is released to the atmosphere. For the first time, the loss of SIC stocks in response to N-induced soil acidification was estimated for Chinese croplands from 1980 to 2020 and forecasts were made up to 2100. The SIC stocks in croplands in 1980 were 2.16 Pg C (16.3 Mg C/ha) in the upper 40 cm, 7% (0.15 Pg C; 1.1 Mg C/ha) of which were lost from 1980 to 2020. During these 40 years, 7 million ha of cropland has become carbonate free. Another 37% of the SIC stocks may be lost up to 2100 in China, leaving 30 million ha of cropland (37.8%) without carbonates if N fertilization follows the business-as-usual (BAU) scenario. Compared to the BAU scenario, the reduction in N input by 15%-30% after 2020 (scenarios S1 and S2) will decrease carbonate dissolution by 18%-41%. If N input remains constant as noted in 2020 (S3) or decreases by 1% annually (S4), a reduction of up to 52%-67% in carbonate dissolution is expected compared to the BAU scenario. The presence of CaCO₃ in the soil is important for various processes including acidity buffering, aggregate formation and stabilization, organic matter stabilization, microbial and enzyme activities, nutrient cycling and availability, and water permeability and plant productivity. Therefore, optimizing N fertilization and improving N-use efficiency are important for decreasing SIC losses from acidification. N application should be strictly calculated based on crop demand, and any overfertilization should be avoided to prevent environmental problems and soil fertility decline associated with CaCO₃ losses.