Interaction of straw amendment and soil NO3- content controls fungal denitrification and denitrification product stoichiometry in a sandy soil

The return of agricultural crop residues are vital to maintain or even enhance soil fertility. However, the influence of application rate of crop residues on denitrification and its related gaseous N emissions is not fully understood. We conducted a fully robotized continuous flow incubation experiment using a Helium/Oxygen atmosphere over 30 days to examine the effect of maize straw application rate on: i) the rate of denitrification, ii) denitrification product stoichiometry N2O/(N2O+N2), and iii) the contribution of fungal denitrification to N2O fluxes. Five treatments were established using sieved, repacked sandy textured soil; i) non-amended control, ii) nitrate only, iii) low rate of straw + nitrate, iv) medium rate of straw + nitrate, and iv) high rate of straw + nitrate (n = 3). We simultaneously measured NO, N2O as well as direct N2 emissions and used the N2O 15N site preference signatures of soil-emitted N2O to distinguish N2O production from fungal and bacterial denitrification. Uniquely, soil NO3− measurements were also made throughout the incubation. Emissions of N2O during the initial phase of the experiment (0–13 days) increased almost linearly with increasing rate of straw incorporation and with (almost) no N2 production. However, the rate of straw amendment was negatively correlated with N2O, but positively correlated with N2 fluxes later in the experimental period (13–30 days). Soil NO3− content, in all treatments, was identified as the main factor responsible for the shift from N2O production to N2O reduction. Straw amendment immediately lowered the proportion of N2O from bacterial denitrification, thus implying that more of the N2O emitted was derived from fungi (18 ± 0.7% in control and up to 40 ± 3.0% in high straw treatments during the first 13 days). However, after day 15 when soil NO3− content decreased to <40 mg NO3−-N kg−1 soil, the N2O 15N site preference values of the N2O produced in the medium straw rate treatment showed a sharp declining trend 15 days after onset of experiment thereby indicating a clear shift towards a more dominant bacterial source of N2O. Our study singularly highlights the complex interrelationship between soil NO3− kinetics, crop residue incorporation, fungal denitrification and N2O/(N2O + N2) ratio. Overall we found that the effect of crop residue applications on soil N2O and N2 emissions depends mainly on soil NO3− content, as NO3− was the primary regulator of the N2O/(N2O + N2) product ratio of denitrification. Furthermore, the application of straw residue enhanced fungal denitrification, but only when the soil NO3− content was sufficient to supply enough electron acceptors to the denitrifiers

Tardive Dyskinesia and Treatment Approaches

Tardive dyskinesia is an iatrogenic movement disorder with an incompletely determined etiology. Involuntary movements can effect oral, lingual, facial, corporal muscles and can be permanent. Tardive dyskinesia is one of the most important side effects of long term antipsychotic use. There is some decrease in tardive dyskinesia rates after common use of second generation antipsychotics but tardive dyskinesia can be seen even after use of second generation antipsychotics. There are some treatment options from drug-free observation to deep brain stimulation in tardive dyskinesia. The aim of this article is to review epidemiology, etiology, risk factors, pathophysiology and treatment options of tardive dyskinesia

Long-term influence of manure and mineral nitrogen applications on plant and soil 15N and 13C values from the Broadbalk Wheat Experiment

The Broadbalk Wheat Experiment at Rothamsted Research in the UK provides a unique opportunity to investigate the long‐term impacts of environmental change and agronomic practices on plants and soils. We examined the influence of manure and mineral fertiliser applications on temporal trends in the stable N (15N) and C (13C) isotopes of wheat collected during 1968–1979 and 1996–2005, and of soil collected in 1966 and 2000. The soil δ15N values in 1966 and 2000 were higher in manure than the mineral N supplied soil; the latter had similar or higher δ15N values than non‐fertilised soil. The straw δ15N values significantly decreased in all N treatments during 1968 to 1979, but not for 1996–2005. The straw δ15N values decreased under the highest mineral N supply (192 kg N ha−1 year−1) by 3‰ from 1968 to 1979. Mineral N supply significantly increased to straw δ13C values in dry years, but not in wet years. Significant correlations existed between wheat straw δ13C values with cumulative rainfall (March to June). The cultivar Hereward (grown 1996–2005) was less affected by changes in environmental conditions (i.e. water stress and fertiliser regime) than Cappelle Desprez (1968–1979). We conclude that, in addition to fertiliser type and application rates, water stress and, importantly, plant variety influenced plant δ13C and δ15N values. Hence, water stress and differential variety response should be considered in plant studies using plant δ13C and δ15N trends to delineate past or recent environmental or agronomic changes

N-Umsatz und Spurengasemissionen typischer Biomassefruchtfolgen zur Biogaserzeugung in Norddeutschland

Im Rahmen des Verbundprojektes Biogas-Expert an der CAU-Kiel wurden an zwei Standorten Schleswig-Holsteins veschiedene Fruchtfolgen zur Bereitstellung von Biogassubstraten unter Verwendung von Biogasgüllen als N-Dünger durchgeführt. Maismonokultur wies die höchsten Trockenmasseerträge auf, wobei keine signifikanten Unterschiede in den Erträgen zwischen Biogasgärresten, organischen N-Düngern und mineralischen Düngern ermittelt wurden. Während in Bezug auf die N-Düngeform bei N2O- und Nitratauswaschungsverlusten kein Einfluss der N-Form auf die Höhe der Verluste festgestellt wurde, war die Düngung mit Biogasgüllen mit signifikant erhöhten NH3-Verlusten verknüpft. Eine abschließende Bewertung der Produktionssysteme ist erst durch Analyse der experimentellen Ergebnisse mit einem Systemmodell möglich

Residue-C effects on denitrification vary with soil depth

Peer reviewedPublisher PD

The effect of nitrification inhibitor on N2O, NO and N2 emissions under different soil moisture levels in a permanent grassland soil

[EN] Emissions of gaseous forms of nitrogen from soil, such as nitrous oxide (N2O) and nitric oxide (NO), have shown great impact on global warming and atmospheric chemistry. Although in soil both nitrification and denitrification could cause N2O and NO emissions, most studies demonstrated that denitrification is the dominant process responsible for the increase of atmospheric N2O, while nitrification produces mostly NO. The use of nitrification inhibitors (NIs) has repeatedly been shown to reduce both N2O and NO emissions from agricultural soils; nevertheless, the efficiency of the mitigation effect varies greatly. It is generally assumed that nitrification inhibitors have no direct effect on denitrification. However, the indirect impact, due to the reduced substrate (nitrate) delivery to microsites where denitrification occurs, may have significant effects on denitrification product stoichiometry that may significantly lower soil borne N2O emissions. Soil-water status is considered to have a remarkable effect on the relative fluxes of nitrogen gases. The effect and mechanism of NI on N2O, NO and N-2 emission under different soil water-filled pore space (WFPS) is still not well explored. In the present study, we conducted a soil incubation experiment in an automated continuous-flow incubation system under a He/O-2 atmosphere. Ammonium sulfate was applied with and without NI (DMPP) to a permanent UK grassland soil under three different soil moisture conditions (50, 65, and 80% WFPS). With every treatment, glucose was applied to supply enough available carbon for denitrification. Emissions of CO2, N2O, NO and N-2 were investigated. Additionally, isotopic signatures of soil-emitted N2O were analyzed. Generally, higher WFPS led to higher N2O and NO emissions, while N-2 emissions were only detected at high soil moisture condition (80% WFPS). Different processes were responsible for N2O and NO emission in different phases of the incubation period. The application of DMPP did significantly reduce both N2O and NO emissions at all three soil moisture conditions. Furthermore, DMPP application increased N-2 emissions and decreased the N2O/(N2O + N-2) product ratio at 80% WFPS. (C) 2017 Elsevier Ltd. All rights reserved.Rothamsted Research is sponsored by the BBSRC. This study was in part funded by BBSRC project BB/K001051/1 and supported by the Chinese Scholarship Council (scholarship no. give number 201306350130).Wu, D.; Cárdenas, LM.; Calvet, S.; Brüggemann, N.; Loick, N.; Liu, S.; Bol, R. (2017). The effect of nitrification inhibitor on N2O, NO and N2 emissions under different soil moisture levels in a permanent grassland soil. Soil Biology and Biochemistry. 113:153-160. https://doi.org/10.1016/j.soilbio.2017.06.007S15316011

“Hot spots” of N and C impact nitric oxide, nitrous oxide and nitrogen gas emissions from a UK grassland soil

Publication history: Accepted - 6 June 2017; Published online - 3 July 2017.Agricultural soils are a major source of nitric- (NO) and nitrous oxide (N2O), which are produced and consumed by biotic and abiotic soil processes. The dominant sources of NO and N2O are microbial nitrification and denitrification, and emissions of NO and N2O generally increase after fertiliser application. The present study investigated the impact of N-source distribution on emissions of NO and N2O from soil and the significance of denitrification, rather than nitrification, as a source of NO emissions. To eliminate spatial variability and changing environmental factors which impact processes and results, the experiment was conducted under highly controlled conditions. A laboratory incubation system (DENIS) was used, allowing simultaneous measurement of three N-gases (NO, N2O, N2) emitted from a repacked soil core, which was combined with 15N-enrichment isotopic techniques to determine the source of N emissions. It was found that the areal distribution of N and C significantly affected the quantity and timing of gaseous emissions and 15N-analysis showed that N2O emissions resulted almost exclusively from the added amendments. Localised higher concentrations, so-called hot spots, resulted in a delay in N2O and N2 emissions causing a longer residence time of the applied N-source in the soil, therefore minimising NO emissions while at the same time being potentially advantageous for plant-uptake of nutrients. If such effects are also observed for a wider range of soils and conditions, then this will have major implications for fertiliser application protocols to minimise gaseous N emissions while maintaining fertilisation efficiency.Rothamsted Research receives strategic funding by the Biotechnology and Biological Sciences Research Council (BBSRC). This study was funded by BBSRC project BB/K001051/1. D. Abalos thanks the Spanish Ministry of Science and Innovation for economic support through the Project AGL2009-08412-AGR