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Agriculture currently accounts for 90% of UK ammonia (NH3) emissions, however, national legally-binding targets are seeking to reduce this by 16% by 2030, relative to 2005 levels. One area which has been targeted to help achieve this target is the lowering of NH3 emissions during livestock manure handling and storage. Slurry acidification represents one potential strategy to abate NH3 throughout the slurry management chain, however, is not currently used in the UK. To address this knowledge gap, two mesocosm-scale experiments were set up to assess the potential for slurry acidification to reduce NH3 emissions at application and to measure impacts on NH3 emissions and short-term changes to soil mineral dynamics and N2O emissions. Experiment 1 determined the impacts of acidified cattle slurry (pH 6.5, 5.5, and 4.8) to conventional (non-acidified) slurry when simulating surface broadcasting. Experiment 2 assessed the impact of conventional and acidified slurry (pH 5.5) using simulated surface broadcasting and shallow injection of cattle slurry. Our results showed that acidification significantly abated NH3 (% of NH4-N applied) from 61.6% for conventional slurry to 26.6% at pH 5.5, and 2.5% at pH 4.8. Acidified surface broadcast was as effective at abating NH3 emissions to injected conventional slurry, and also delayed nitrification, while not significantly altering N2O emissions from conventional slurry. Our results strongly suggest that slurry acidification could be a viable strategy to help the UK reach its NH3 reduction target and exceed the current abatement potential through combining low emissions spreading techniques with acidification.
<h3>In Reply.</h3> —We appreciate the concerns raised by Dr Rothschild. Since significantly lower cost to the patient encourages use of our managed health care system, it is unlikely that many of our patients who developed gastrointestinal complications were hospitalized in other facilities. All of our gastroenterologists responded to our survey, and 9 perceived an increase in NSAID-associated gastropathy. However, as we emphasized, physician perception of patient harm may indeed underestimate the frequency of actual adverse effects. All NSAIDs may cause gastrointestinal and other complications. Differences in risk are probably dose dependent, and differences in equipotent doses have not been shown to be clinically significant. Our guideline did not require the use of maximal NSAID doses before progression to other agents. In the year following our intervention, our guideline resulted in volume-adjusted increases of 12% for nonacetylated salicylates and more than 25% for acetaminophen. We did not evaluate the effect of these
The urine patch from livestock creates an active hotspot of soil nitrogen (N) cycling due to the intrinsically high N and carbon (C) loading rates. These N hotspots frequently result in N losses to the atmosphere or leaching from soil. N losses vary due to climate conditions, soil conditions, and management practices. However, we do not fully understand how these factors influence N cycling and nitrous oxide (N2O) emissions from urine patches. Intensive lowland grazing systems on mineral soils have been relatively well studied in this context, however, other grazing systems such as extensive upland systems on organic soils have been much less studied.To investigate the effect of soil type on N cycling and N2O emissions in the urine patch, soil was collected from pastures in an altitudinal gradient, from an improved lowland mineral soil with coastal influence to unimproved organic soil under acid grassland. &#160;Depending on the position along the gradient, the soils change in properties such as pH, bulk density, organic matter content, cation exchange capacity and nutrient availability. Soil was collected for a laboratory incubation study from four sites including two lowland sites (Cambisol and Cambisol with coastal influence) and two upland sites (Podzol and Histosol). Soils were sieved and divided into four replicates of each treatment. Sheep urine from Welsh Mountain ewes was applied at an equivalent loading rate of 150 kg N ha-1 to half of the soil and the remaining half received the equivalent volume of water as a control. All the treatments were held at 70% water-filled pore space to optimise both moisture conditions for nitrification and denitrification to occur. Over 100 days, greenhouse gas emissions were monitored along with soil pore water nitrate and ammonium concentrations.Soil type had an overall significant effect on N2O emissions with the highest cumulative emissions during this period being from the Podzol and the lowest cumulative emissions being from the Histosol. The two lowland sites showed no significant differences. There was a delay in nitrification in the Podzol, with the majority of the N2O being emitted a month after urine application. The Histosol showed no evidence of nitrification as there was no build-up of nitrate concentrations over the experiment. This was probably due to differences in soil pH in the soils. There were no differences in carbon dioxide or methane emissions from the four soils, but there was a spike in methane flux on the Podzol which corresponded with increases in N2O fluxes from this soil type.This experiment has shown that certain upland soils have the potential to produce N2O emissions and cycle N under optimal conditions, although this is at a much slower rate than the lowland sites. Results from this incubation study helps improve our understanding of how soil properties in organic soils affect N cycling and contribute to knowledge gaps on the sustainability of upland grazing systems.
Plant roots and microorganisms interact and compete for nutrients within the rhizosphere, which is considered one of the most biologically complex systems on Earth. Unraveling the nitrogen (N) cycle is key to understanding and managing nutrient flows in terrestrial ecosystems, yet to date it has proved impossible to analyze and image N transfer in situ within such a complex system at a scale relevant to soil-microbe-plant interactions. Linking the physical heterogeneity of soil to biological processes marks a current frontier in plant and soil sciences. Here we present a new and widely applicable approach that allows imaging of the spatial and temporal dynamics of the stable isotope 15N assimilated within the rhizosphere. This approach allows visualization and measurement of nutrient resource capture between competing plant cells and microorganisms. For confirmation we show the correlative use of nanoscale secondary ion mass spectrometry, and transmission electron microscopy, to image differential partitioning of 15NH4+ between plant roots and native soil microbial communities at the submicron scale. It is shown that 15N compounds can be detected and imaged in situ in individual microorganisms in the soil matrix and intracellularly within the root. Nanoscale secondary ion mass spectrometry has potential to allow the study of assimilatory processes at the submicron level in a wide range of applications involving plants, microorganisms, and animals.
Agri‐environment schemes (AES) incentivise land‐management practices aimed at mitigating environmental impacts. However, their effectiveness depends on the duration and type of management. We modelled the potential for grassland AES options in Wales (UK) to achieve positive changes in plant diversity via change in soil conditions. We modelled the response of plants and soils to the predicted effects of AES options over a 13‐year time interval. We applied scenarios of change in soil conditions in three managed grassland types, using high‐resolution baseline soil and vegetation data collected in grasslands across Wales, UK. We also applied scenarios of climate change to determine the extent to which this might modify the impact of AES intervention on plant species compositional turnover. Empirical models of soil response to extensification were constructed from published experimental data and used to drive change in soil inputs to a small ensemble of ecological niche models for British plants. These models were applied to the local pool of species in each baseline (2 × 2 m) quadrat plus a wider 10 × 10 km pool from which we draw species absent at baseline but predicted to find conditions suitable as a result of AES intervention and climate change, thus estimating dark diversity at each location. Outputs were summarised by grouping species by the ecosystem functions and services they support and by matching projected species composition to the UK National Vegetation Classification. Scenario modelling indicated that at least 10 years of management under grassland AES options were needed to achieve conditions suitable for desirable plant assemblages more typical of lower fertility habitats. Synthesis and applications : We predict that management effects will have a more marked effect on vegetation and soil than predicted climate variation up to 2029. Realising modelled changes in habitat suitability as species compositional turnover and community assembly is likely to require additional measures to assist plant dispersal and establishment.
