Co-benefits for net carbon emissions and rice yields through improved management of organic nitrogen and water.

Returning organic nutrient sources (for example, straw and manure) to rice fields is inevitable for coupling crop-livestock production. However, an accurate estimate of net carbon (C) emissions and strategies to mitigate the abundant methane (CH4) emission from rice fields supplied with organic sources remain unclear. Here, using machine learning and a global dataset, we scaled the field findings up to worldwide rice fields to reconcile rice yields and net C emissions. An optimal organic nitrogen (N) management was developed considering total N input, type of organic N source and organic N proportion. A combination of optimal organic N management with intermittent flooding achieved a 21% reduction in net global warming potential and a 9% rise in global rice production compared with the business-as-usual scenario. Our study provides a solution for recycling organic N sources towards a more productive, carbon-neutral and sustainable rice-livestock production system on a global scale.

The predictive role of symptoms in COVID-19 diagnostic models: A longitudinal insight.

To investigate the symptoms of SARS-CoV-2 infection, their dynamics and their discriminatory power for the disease using longitudinally, prospectively collected information reported at the time of their occurrence. We have analysed data from a large phase 3 clinical UK COVID-19 vaccine trial. The alpha variant was the predominant strain. Participants were assessed for SARS-CoV-2 infection via nasal/throat PCR at recruitment, vaccination appointments, and when symptomatic. Statistical techniques were implemented to infer estimates representative of the UK population, accounting for multiple symptomatic episodes associated with one individual. An optimal diagnostic model for SARS-CoV-2 infection was derived. The 4-month prevalence of SARS-CoV-2 was 2.1%; increasing to 19.4% (16.0%-22.7%) in participants reporting loss of appetite and 31.9% (27.1%-36.8%) in those with anosmia/ageusia. The model identified anosmia and/or ageusia, fever, congestion, and cough to be significantly associated with SARS-CoV-2 infection. Symptoms' dynamics were vastly different in the two groups; after a slow start peaking later and lasting longer in PCR+ participants, whilst exhibiting a consistent decline in PCR- participants, with, on average, fewer than 3 days of symptoms reported. Anosmia/ageusia peaked late in confirmed SARS-CoV-2 infection (day 12), indicating a low discrimination power for early disease diagnosis.

Tackling late HIV diagnosis: Lessons from the UK in the COVID-19 era.

INTRODUCTION: Late diagnosis of HIV is associated with increased morbidity and mortality, and an increased risk of non-infectious comorbidities. On a societal level, late diagnosis leads to higher treatment and healthcare costs and is a major driver of HIV transmission. Despite improvements in other areas of the HIV care pathway, late diagnosis remains an individual and public health concern globally. OBJECTIVE: To examine the barriers to HIV testing and highlight successful strategies to improve prompt diagnosis. This review describes the prevalence of late diagnosis in the UK and discusses key factors that contribute to late diagnosis, including the effect of the COVID-19 pandemic. Late HIV diagnosis is lower in the UK than in most other European countries. In this review, pilot projects and ongoing initiatives that have reduced late diagnosis in the UK are highlighted; moreover, further strategies for improving prompt diagnosis are suggested. CONCLUSIONS: Insufficient testing is the fundamental reason for late HIV diagnosis, with societal, systemic, and individual factors all contributing to inadequate testing. Improving access to testing, removing barriers to health-seeking behaviour, and ensuring all people with HIV indicator conditions are promptly tested are key to reducing the rates of late diagnosis globally.

Postoperative Staphylococcus aureus Infections in Patients With and Without Preoperative Colonization.

Importance: Staphylococcus aureus surgical site infections (SSIs) and bloodstream infections (BSIs) are important complications of surgical procedures for which prevention remains suboptimal. Contemporary data on the incidence of and etiologic factors for these infections are needed to support the development of improved preventive strategies. Objectives: To assess the occurrence of postoperative S aureus SSIs and BSIs and quantify its association with patient-related and contextual factors. Design, Setting, and Participants: This multicenter cohort study assessed surgical patients at 33 hospitals in 10 European countries who were recruited between December 16, 2016, and September 30, 2019 (follow-up through December 30, 2019). Enrolled patients were actively followed up for up to 90 days after surgery to assess the occurrence of S aureus SSIs and BSIs. Data analysis was performed between November 20, 2020, and April 21, 2022. All patients were 18 years or older and had undergone 11 different types of surgical procedures. They were screened for S aureus colonization in the nose, throat, and perineum within 30 days before surgery (source population). Both S aureus carriers and noncarriers were subsequently enrolled in a 2:1 ratio. Exposure: Preoperative S aureus colonization. Main Outcomes and Measures: The main outcome was cumulative incidence of S aureus SSIs and BSIs estimated for the source population, using weighted incidence calculation. The independent association of candidate variables was estimated using multivariable Cox proportional hazards regression models. Results: In total, 5004 patients (median [IQR] age, 66 [56-72] years; 2510 [50.2%] female) were enrolled in the study cohort; 3369 (67.3%) were S aureus carriers. One hundred patients developed S aureus SSIs or BSIs within 90 days after surgery. The weighted cumulative incidence of S aureus SSIs or BSIs was 2.55% (95% CI, 2.05%-3.12%) for carriers and 0.52% (95% CI, 0.22%-0.91%) for noncarriers. Preoperative S aureus colonization (adjusted hazard ratio [AHR], 4.38; 95% CI, 2.19-8.76), having nonremovable implants (AHR, 2.00; 95% CI, 1.15-3.49), undergoing mastectomy (AHR, 5.13; 95% CI, 1.87-14.08) or neurosurgery (AHR, 2.47; 95% CI, 1.09-5.61) (compared with orthopedic surgery), and body mass index (AHR, 1.05; 95% CI, 1.01-1.08 per unit increase) were independently associated with S aureus SSIs and BSIs. Conclusions and Relevance: In this cohort study of surgical patients, S aureus carriage was associated with an increased risk of developing S aureus SSIs and BSIs. Both modifiable and nonmodifiable etiologic factors were associated with this risk and should be addressed in those at increased S aureus SSI and BSI risk.

Differential cellular and humoral immune responses in immunocompromised individuals following multiple SARS-CoV-2 vaccinations.

Introduction: The heterogeneity of the immunocompromised population means some individuals may exhibit variable, weak or reduced vaccine-induced immune responses, leaving them poorly protected from COVID-19 disease despite receiving multiple SARS-CoV-2 vaccinations. There is conflicting data on the immunogenicity elicited by multiple vaccinations in immunocompromised groups. The aim of this study was to measure both humoral and cellular vaccine-induced immunity in several immunocompromised cohorts and to compare them to immunocompetent controls. Methods: Cytokine release in peptide-stimulated whole blood, and neutralising antibody and baseline SARS-CoV-2 spike-specific IgG levels in plasma were measured in rheumatology patients (n=29), renal transplant recipients (n=46), people living with HIV (PLWH) (n=27) and immunocompetent participants (n=64) post third or fourth vaccination from just one blood sample. Cytokines were measured by ELISA and multiplex array. Neutralising antibody levels in plasma were determined by a 50% neutralising antibody titre assay and SARS-CoV-2 spike specific IgG levels were quantified by ELISA. Results: In infection negative donors, IFN-γ, IL-2 and neutralising antibody levels were significantly reduced in rheumatology patients (p=0.0014, p=0.0415, p=0.0319, respectively) and renal transplant recipients (p<0.0001, p=0.0005, p<0.0001, respectively) compared to immunocompetent controls, with IgG antibody responses similarly affected. Conversely, cellular and humoral immune responses were not impaired in PLWH, or between individuals from all groups with previous SARS-CoV-2 infections. Discussion: These results suggest that specific subgroups within immunocompromised cohorts could benefit from distinct, personalised immunisation or treatment strategies. Identification of vaccine non-responders could be critical to protect those most at risk.

Hepmarc: A 96 week randomised controlled feasibility trial of add-on maraviroc in people with HIV and non-alcoholic fatty liver disease.

OBJECTIVES: Maraviroc may reduce hepatic inflammation in people with HIV and non-alcoholic fatty liver disease (HIV-NAFLD) through CCR5-receptor antagonism, which warrants further exploration. METHODS: We performed an open-label 96-week randomised-controlled feasibility trial of maraviroc plus optimised background therapy (OBT) versus OBT alone, in a 1:1 ratio, for people with virologically-suppressed HIV-1 and NAFLD without cirrhosis. Dosing followed recommendations for HIV therapy in the Summary of Product Characteristics for maraviroc. The primary outcomes were safety, recruitment and retention rates, adherence and data completeness. Secondary outcomes included the change in Fibroscan-assessed liver stiffness measurements (LSM), controlled attenuation parameter (CAP) and Enhanced Liver Fibrosis (ELF) scores. RESULTS: Fifty-three participants (53/60, 88% of target) were recruited; 23 received maraviroc plus OBT; 89% were male; 19% had type 2 diabetes mellitus. The median baseline LSM, CAP & ELF scores were 6.2 (IQR 4.6-7.8) kPa, 325 (IQR 279-351) dB/m and 9.1 (IQR 8.6-9.6) respectively. Primary outcomes: all individuals eligible after screening were randomised; there was 92% (SD 6.6%) adherence to maraviroc [target >90%]; 83% (95%CI 70%-92%) participant retention [target >65%]; 5.5% of data were missing [target <20%]. There were noo Serious Adverse Reactions; mild-moderate intensity Adverse Reactions were reported by five participants (5/23, 22% (95%CI 5%-49%)) [target <10%]. All Adverse Reactions resolved. Secondary outcomes: no important differences were seen by treatment group for the change from baseline in LSM, CAP or ELF scores. CONCLUSIONS: This feasibility study provides preliminary evidence of maraviroc safety amongst people with HIV-NAFLD, and acceptable recruitment, retention, and adherence rates. These data support a definitive randomised-controlled trial assessing maraviroc impact on hepatic steatosis and fibrosis. TRIAL REGISTRATION: Clinical trial registry: ISCRTN, registration number 31461655.

Increasing concentration of pure micro- and macro-LDPE and PP plastic negatively affect crop biomass, nutrient cycling, and microbial biomass.

Over the last 50 years, the intense use of agricultural plastic in the form of mulch films has led to an accumulation of plastic in soil, creating a legacy of plastic in agricultural fields. Plastic often contains additives, however it is still largely unknown how these compounds affect soil properties, potentially influencing or masking effects of the plastic itself. Therefore, the aim of this study was to investigate the effects of pure plastics of varying sizes and concentrations, to improve our understanding of plastic-only interactions within soil-plant mesocosms. Maize (Zea mays L.) was grown over eight weeks following the addition of micro and macro low-density polyethylene and polypropylene at increasing concentrations (equivalent to 1, 10, 25, and 50 years mulch film use) and the effects of plastic on key soil and plant properties were measured. We found the effect of both macro and microplastic on soil and plant health is negligible in the short-term (1 to <10 years). However, ≥ 10 years of plastic application for both plastic types and sizes resulted in a clear negative effect on plant growth and microbial biomass. This study provides vital insight into the effect of both macro and microplastics on soil and plant properties.

Biochar application to temperate grasslands: challenges and opportunities for delivering multiple ecosystem services.

Grasslands (natural, semi-natural and improved) occupy approximately one-third of the terrestrial biosphere and are key for global ecosystem service provision, storing up to 30% of soil organic carbon (SOC). To date, most research on soil carbon (C) sequestration has focused on croplands where the levels of native soil organic matter (SOM) are typically low and significant potential exists to replenish SOM stocks. However, with the renewed push to achieve "net zero" C emissions by 2050, grasslands may offer an additional C store, utilising tools such as biochar. Here, we critically evaluate the potential for biochar as a technology for increasing grassland C stocks, identifying a number of practical, economic, social and legislative challenges that need to be addressed before the widescale adoption of biochar may be achieved. We critically assess the current knowledge within the field of grassland biochar research in the context of ecosystem service provision and provide opinions on the applicability of biochar as an amendment to different types of grassland (improved, semi-improved and unimproved) and the potential effect on ecosystem provision using a range of application techniques in the topsoil and subsoil. We concluded that the key question remains, is it possible for managed grasslands to store more C, without causing a loss in additional ecosystem services? To address this question future research must take a more multidisciplinary and holistic approach when evaluating the potential role of biochar at sequestering C in grasslands to mitigate climate change. Supplementary Information: The online version contains supplementary material available at 10.1007/s42773-023-00232-y.

COVID-19 infection in people living with HIV.

BACKGROUND: Coronavirus disease 2019 (COVID-19) and human immunodeficiency virus (HIV) are intersecting pandemics, with implications for care at an individual and global scale. SOURCES OF DATA: PubMed search with relevant articles and their references reviewed. AREAS OF AGREEMENT: COVID-19 has changed the delivery of care to people living with HIV (PLWH). Vaccines are efficacious and safe for PLWH; patient care for symptomatic COVID-19 is similar to that of people without HIV. AREAS OF CONTROVERSY: It remains unclear whether PLWH experience increased COVID-19-specific mortality. Treatments to reduce severity in early COVID-19 infection lack evidence in PLWH. GROWING POINTS: The effects of the COVID-19 pandemic on HIV-related morbidity and mortality are yet to be seen. COVID-19 epidemiology among PLWH is complicated by changes to the severe acute respiratory syndrome coronavirus 2, population behaviours and vaccine availability. AREAS TIMELY FOR DEVELOPING RESEARCH: Global trends in HIV-related morbidity and mortality should be monitored to appreciate the effects of the COVID-19 pandemic. The benefits of early antiviral and/or neutralizing monoclonal antibody (nMAb) treatment for PLWH and nMAb prophylaxis require investigation.

Increased adverse events following third dose of BNT162b2/Pfizer vaccine in those with previous COVID-19, but not with concurrent influenza vaccine.

Prior studies suggest that adverse events (AEs) following doses one and two of BNT162b2/Pfizer vaccine are worse in those with a prior history of COVID-19. To establish whether this outcome applies to a third/booster dose, we conducted a survey with 534 healthcare workers (HCW) in Northeast England, who reported AEs following all three doses of BNT162b2/Pfizer vaccine. We also explored AEs associated with concurrent seasonal influenza immunisation, in a subset of 492 HCWs. For all doses of BNT162b2/Pfizer vaccine there was a cluster of systemic AEs that were consistently worse in HCWs with a prior history of COVID-19. AEs were no worse in HCWs who received their third/booster dose within 7 days of the influenza jab, rather than further apart. Gender and the presence of ongoing COVID-19 symptoms (OCS) had no effect on AEs associated with COVID-19 or influenza vaccination, though younger HCWs experienced more AEs overall. Our findings have implications for vaccine hesitancy and immunisation protocols.

Atmospheric deposition of microplastics in a rural region of North China Plain.

Microplastics (MPs) pollution is becoming one of the most pressing environmental issues globally. MPs in the marine, freshwater and terrestrial environments have been fairly well investigated. However, knowledge of the atmospheric-mediated deposition of MPs within rural environments is limited. Here, we present the results of bulk (dry and wet) atmospheric MPs deposition in a rural region of Quzhou County in the North China Plain (NCP). Samples of MPs in the atmospheric bulk deposition were collected for individual rainfall events over a 12-month period from August 2020 to August 2021. The number and size of MPs from 35 rainfall samples were measured by fluorescence microscopy, while the chemical composition of MPs was identified using micro-Fourier transform infrared spectroscopy (µ-FTIR). The results showed that the atmospheric MPs deposition rate in summer (892-75,421 particles/m2/day) was highest compared to 735-9428, 280-4244 and 86-1347 particles/m2/day in spring, autumn, and winter, respectively. Furthermore, the MPs deposition rates in our study were 1-2 orders of magnitude higher than those in other regions, indicating a higher rate of MPs deposition in the rural region of the NCP. MPs with a diameter of 3-50 µm accounted for 75.6 %, 78.4 %, 73.4 % and 66.1 % of total MPs deposition in spring, summer, autumn, and winter, respectively, showing that the majority of MPs in the current study were small in size. Rayon fibers accounted for the largest proportion (32 %) of all MPs, followed by polyethylene terephthalate (12 %) and polyethylene (8 %). This study also found that a significant positive correlation between rainfall volume and MPs deposition rate. In addition, HYSPLIT back-trajectory modelling showed that the farthest source of deposition MPs may have come from Russia.

Recommendations for defining preventable HIV-related mortality for public health monitoring in the era of Getting to Zero: an expert consensus.

Getting to Zero is a commonly cited strategic aim to reduce mortality due to both HIV and avoidable deaths among people with HIV. However, no clear definitions are attached to these aims with regard to what constitutes HIV-related or preventable mortality, and their ambition is limited. This Position Paper presents consensus recommendations to define preventable HIV-related mortality for a pragmatic approach to public health monitoring by use of national HIV surveillance data. These recommendations were informed by a comprehensive literature review and agreed by 42 international experts, including clinicians, public health professionals, researchers, commissioners, and community representatives. By applying the recommendations to 2019 national HIV surveillance data from the UK, we show that 30% of deaths among people with HIV were HIV-related or possibly HIV-related, and at least 63% of these deaths were preventable or potentially preventable. The application of these recommendations by health authorities will ensure consistent monitoring of HIV elimination targets and allow for the identification of inequalities and areas for intervention.

Leaching of phthalate acid esters from plastic mulch films and their degradation in response to UV irradiation and contrasting soil conditions.

Phthalate acid esters (PAEs) are commonly used plastic additives, not chemically bound to the plastic that migrate into surrounding environments, posing a threat to environmental and human health. Dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) are two common PAEs found in agricultural soils, where degradation is attributed to microbial decomposition. Yet the impact of the plastic matrix on PAE degradation rates is poorly understood. Using 14C-labelled DBP and DEHP we show that migration from the plastic matrix into soil represents a key rate limiting step in their bioavailability and subsequent degradation. Incorporating PAEs into plastic film decreased their degradation in soil, DBP (DEHP) from 79% to 21% (9% to <1%), over four months when compared to direct application of PAEs. Mimicking surface soil conditions, we demonstrated that exposure to ultraviolet radiation accelerated PAE mineralisation twofold. Turnover of PAE was promoted by the addition of biosolids, while the presence of plants and other organic residues failed to promote degradation. We conclude that PAEs persist in soil for longer than previously thought due to physical trapping within the plastic matrix, suggesting PAEs released from plastics over very long time periods lead to increasing levels of contamination.

Resilience of ecosystem service delivery in grasslands in response to single and compound extreme weather events.

Extreme weather events are increasing in frequency and magnitude with profound effects on ecosystem functioning. Further, there is now a greater likelihood that multiple extreme events are occurring within a single year. Here we investigated the effect of a single drought, flood or compound (flood + drought) extreme event on temperate grassland ecosystem processes in a field experiment. To assess system resistance and resilience, we studied changes in a wide range of above- and below-ground indicators (plant diversity and productivity, greenhouse gas emissions, soil chemical, physical and biological metrics) during the 8 week stress events and then for 2 years post-stress. We hypothesized that agricultural grasslands would have different degrees of resistance and resilience to flood and drought stress. We also investigated two alternative hypotheses that the combined flood + drought treatment would either, (A) promote ecosystem resilience through more rapid recovery of soil moisture conditions or (B) exacerbate the impact of the single flood or drought event. Our results showed that flooding had a much greater effect than drought on ecosystem processes and that the grassland was more resistant and resilient to drought than to flood. The immediate impact of flooding on all indicators was negative, especially for those related to production, and climate and water regulation. Flooding stress caused pronounced and persistent shifts in soil microbial and plant communities with large implications for nutrient cycling and long-term ecosystem function. The compound flood + drought treatment failed to show a more severe impact than the single extreme events. Rather, there was an indication of quicker recovery of soil and microbial parameters suggesting greater resilience in line with hypothesis (A). This study clearly reveals that contrasting extreme weather events differentially affect grassland ecosystem function but that concurrent events of a contrasting nature may promote ecosystem resilience to future stress.

The British HIV Association national clinical audit 2021: Management of HIV and hepatitis C coinfection.

OBJECTIVES: We aimed to describe clinical policies for the management of people with HIV/hepatitis C virus (HCV) coinfection and to audit routine monitoring and assessment of people with HIV/HCV coinfection attending UK HIV care. METHODS: This was a clinic survey and retrospective case-note review. HIV clinics in the UK participated in the audit from May to July 2021 by completing an online questionnaire regarding their clinic's policies for the management of people with HIV/HCV coinfection, and by contributing to a case-note review of people living with HIV with detectable HCV RNA who were under the care of their service. RESULTS: Ninety-five clinics participated in the clinic survey; of these, 15 (15.8%) were regional specialist centres, 19 (20.0%) were HIV services with their own coinfection clinics, 40 (42.1%) were HIV services that referred coinfected individuals to a local hepatology service and 20 (21.1%) were HIV services that referred to a regional specialist centre. Eighty-one clinics provided full caseload estimates; of the approximately 3951 people with a history of HIV/HCV coinfection accessing their clinics, only 4.9% were believed to have detectable HCV RNA, 3.15% of whom were already receiving or approved for direct-acting antiviral (DAA) treatment. In total, 29 (30.5%) of the clinics reported an impact of COVID-19 on coinfection care, including delays or reductions in the frequency of services, monitoring, treatment initiation and appointments, and changes to the way that treatment was dispensed. Case-note reviews were provided for 283 people with detectable HCV RNA from 74 clinics (median age 42 years, 74.6% male, 56.2% HCV genotype 1, 22.3% HCV genotype 3). Overall, 56% had not received treatment for HCV, primarily due to lack of engagement in care (54.7%) and/or being uncontactable (16.4%). CONCLUSIONS: Our findings show that the small number of people with HIV with detectable HCV RNA in the UK should mean that it is possible to achieve HCV micro-elimination. However, more work is needed to improve engagement in care for those who are untreated for HCV.

Safety and Efficacy of the NVX-CoV2373 Coronavirus Disease 2019 Vaccine at Completion of the Placebo-Controlled Phase of a Randomized Controlled Trial.

BACKGROUND: The recombinant protein-based vaccine, NVX-CoV2373, demonstrated 89.7% efficacy against coronavirus disease 2019 (COVID-19) in a phase 3, randomized, observer-blinded, placebo-controlled trial in the United Kingdom. The protocol was amended to include a blinded crossover. Data to the end of the placebo-controlled phase are reported. METHODS: Adults aged 18-84 years received 2 doses of NVX-CoV2373 or placebo (1:1) and were monitored for virologically confirmed mild, moderate, or severe COVID-19 (onset from 7 days after second vaccination). Participants who developed immunoglobulin G (IgG) against nucleocapsid protein but did not show symptomatic COVID-19 were considered asymptomatic. Secondary outcomes included anti-spike (S) IgG responses, wild-type virus neutralization, and T-cell responses. RESULTS: Of 15 185 participants, 13 989 remained in the per-protocol efficacy population (6989 NVX-CoV2373, 7000 placebo). At a maximum of 7.5 months (median, 4.5) postvaccination, there were 24 cases of COVID-19 among NVX-CoV2373 recipients and 134 cases among placebo recipients, a vaccine efficacy of 82.7% (95% confidence interval [CI], 73.3%-88.8%). Vaccine efficacy was 100% (95% CI, 17.9%-100.0%) against severe disease and 76.3% (95% CI, 57.4%-86.8%) against asymptomatic disease. High anti-S and neutralization responses to vaccination were evident, together with S-protein-specific induction of interferon-γ secretion in peripheral blood T cells. Incidence of serious adverse events and adverse events of special interest were similar between groups. CONCLUSIONS: A 2-dose regimen of NVX-CoV2373 conferred a high level of ongoing protection against asymptomatic, symptomatic, and severe COVID-19 through >6 months postvaccination. A gradual decrease of protection suggests that a booster may be indicated. CLINICAL TRIALS REGISTRATION: EudraCT, 2020-004123-16.

Separating N2O production and consumption in intact agricultural soil cores at different moisture contents and depths.

Agricultural soils are a major source of the potent greenhouse gas and ozone depleting substance, N2O. To implement management practices that minimize microbial N2O production and maximize its consumption (i.e., complete denitrification), we must understand the interplay between simultaneously occurring biological and physical processes, especially how this changes with soil depth. Meaningfully disentangling of these processes is challenging and typical N2O flux measurement techniques provide little insight into subsurface mechanisms. In addition, denitrification studies are often conducted on sieved soil in altered O2 environments which relate poorly to in situ field conditions. Here, we developed a novel incubation system with headspaces both above and below the soil cores and field-relevant O2 concentrations to better represent in situ conditions. We incubated intact sandy clay loam textured agricultural topsoil (0-10 cm) and subsoil (50-60 cm) cores for 3-4 days at 50% and 70% water-filled pore space, respectively. 15N-N2O pool dilution and an SF6 tracer were injected below the cores to determine the relative diffusivity and the net N2O emission and gross N2O emission and consumption fluxes. The relationship between calculated fluxes from the below and above soil core headspaces confirmed that the system performed well. Relative diffusivity did not vary with depth, likely due to the preservation of preferential flow pathways in the intact cores. Gross N2O emission and uptake also did not differ with depth but were higher in the drier cores, contrary to expectation. We speculate this was due to aerobic denitrification being the primary N2O consuming process and simultaneously occurring denitrification and nitrification both producing N2O in the drier cores. We provide further evidence of substantial N2O consumption in drier soil but without net negative N2O emissions. The results from this study are important for the future application of the 15N-N2O pool dilution method and N budgeting and modelling, as required for improving management to minimize N2O losses.

Development of a LoRaWAN IoT Node with Ion-Selective Electrode Soil Nitrate Sensors for Precision Agriculture.

Crop productivity is highly dependent on the availability of soluble nitrogen (N), e.g. nitrate, in soil. When N levels are low, fertilisers are applied to replenish the soil's reserves. Typically the timing of these applications is based on paper-based guidance and sensor-based measurements of canopy greenness, which provides an indirect measure of soil N status. However this approach often means that N fertiliser is applied inappropriately or too late, resulting in excess N being lost to the environment, or too little N to meet crop demand. To promote greater N use efficiency and improve agricultural sustainability, we developed an Internet of Things (IoT) approach for the real-time measurement of soil nitrate levels using ion-selective membrane sensors in combination with digital soil moisture probes. The node incorporates state-of-the-art IoT connectivity using a LoRaWAN transceiver. The sensing platform can transfer real-time data via a cloud-connected gateway for processing and storage. In summary, we present a validated soil sensor system for real-time monitoring of soil nitrate concentrations, which can support fertiliser management decisions, improve N use efficiency and reduce N losses to the environment.