A Hierarchical Spatio-Temporal Statistical Model Motivated by Glaciology

In this paper, we extend and analyze a Bayesian hierarchical spatio-temporal model for physical systems. A novelty is to model the discrepancy between the output of a computer simulator for a physical process and the actual process values with a multivariate random walk. For computational efficiency, linear algebra for bandwidth limited matrices is utilized, and first-order emulator inference allows for the fast emulation of a numerical partial differential equation (PDE) solver. A test scenario from a physical system motivated by glaciology is used to examine the speed and accuracy of the computational methods used, in addition to the viability of modeling assumptions. We conclude by discussing how the model and associated methodology can be applied in other physical contexts besides glaciology.Comment: Revision accepted for publication by the Journal of Agricultural, Biological, and Environmental Statistic

Nitrogen budgets and soil nitrogen stocks of organic and conventional cropping systems: how reconcile efficiency and sustainability of nitrogen use?

Organic and conventional cropping systems differ in the nature and amounts of nitrogen (N) inputs, which may affect efficiency and sustainability of N use. In the DOK (bio-Dynamic, bio-Organic, Konventionell) field experiment, organic and conventional cropping systems have been compared since 1978 at two fertilization levels (with level 2 being typical for the respective system and level 1 receiving half of this dose)

Phosphorus (P) availability and P transformation rates in Amazonian Dark Earth determined by 33P isotopic dilution.

Amazonian Dark Earth (ADE) often shows increased soil fertility compared to surrounding soils, likely linked to its increased concentration of soil organic matter and macronutrients such as phosphorus (P). For P, there is little knowledge whether the higher P availability is a result of increased biological processes (such as organic P mineralization) or physico-chemical processes (such as sorption/desorption), or both

Characterization of Residual Chlorinated Organic Compounds in the Soil and Sediment at the Wilson`s Corner Site

Depth discrete bulk sediment samples were collected from 15 different location at the Wilson`s Corner site on the Kennedy Space Center during August 1996

Spring warming in Yukon mountains is not amplified by the snow albedo feedback

Decreasing spring snow cover may amplify Arctic warming through the snow albedo feedback. To examine the impact of snowmelt on increasing temperature we used a 5,000 m elevation gradient in Yukon, Canada, extending from valley-bottom conifer forests, through middle elevation tundra, to high elevation icefields, to compare validated downscaled reanalysis air temperature patterns across elevational bands characterized by different patterns of spring snowmelt. From 2000 to 2014 we observed surface warming of 0.01 °C/a·1,000 m in May (0.14 °C/a at 1,000 m to 0.19 °C/a at 5,000 m), and uniform cooling of 0.09 °C/a in June at all elevations. May temperature trends across elevationally dependent land cover types were highly correlated with each other despite large variations in albedo and snow cover trends. Furthermore, a clear dependency of infrared skin temperature on snow cover mediated albedo decline was observed in tundra, but this was insufficient to influence average diurnal air temperature. We observed negative June temperature trends which we attribute to increasing daytime cloud cover because albedo and snow cover trends were unchanging. We conclude that 8-day and monthly averaged Spring air temperature trends are responding to a synoptic external forcing that is much stronger than the snow albedo feedback in sub-Arctic mountains

Delivery of stable ultra-thin liquid sheets in vacuum for biochemical spectroscopy

The development of ultra-thin flat liquid sheets capable of running in vacuum has provided an exciting new target for X-ray absorption spectroscopy in the liquid and solution phases. Several methods have become available for delivering in-vacuum sheet jets using different nozzle designs. We compare the sheets produced by two different types of nozzle; a commercially available borosillicate glass chip using microfluidic channels to deliver colliding jets, and an in-house fabricated fan spray nozzle which compresses the liquid on an axis out of a slit to achieve collision conditions. We find in our tests that both nozzles are suitable for use in X-ray absorption spectroscopy with the fan spray nozzle producing thicker but more stable jets than the commercial nozzle. We also provide practical details of how to run these nozzles in vacuum

Land use change in Amazonian Dark Earth and Acrisol: responses of organic carbon, organic matter composition and microbial carbon utilisation.

The conversion of tropical forest for cassava cultivation is widely known to decrease the soil organic matter (OM) and nutrient contents of highly weathered soils in the tropics. Amazonian Dark Earth (ADE) might be affected less due to their historical anthropogenic amelioration with e.g. charcoal, ceramics and bones, leading to higher soil OM and nutrient concentrations. In this study, we analysed the effect of land use change on the OM dynamics and its composition under tropical conditions, using ADE and an adjacent Acrisol (ACR) as model systems

NPK Bilanzen von ökologischer und konventioneller Landwirtschaft im Vergleich: Ergebnisse eines 35-jährigen Feldversuches

Die Ausreichende Verfügbarkeit von Stickstoff (N), Phosphor (P) und Kalium (K) ist essentiell für einen konstanten Ernteertrag in landwirtschaftlichen Systemen. Im DOK-Versuch in Therwil (Schweiz) wird seit 1978 ein Systemvergleich zwischen ökologischer und konventioneller Landwirtschaft im Rahmen eines Feldversuches betrieben. Die Verfahren biologisch-dynamisch (DYN) und organisch-biologisch (ORG) werden nur mit Stallmist gedüngt, während im konventionellen Verfahren (KON) zusätzlich mit Mineraldünger ausgeglichen wird. Im mineralisch gedüngten Verfahren (MIN) wird nur Mineraldünger ausgebracht, in der ungedüngten Kontrollfläche (NON) erfolgt seit Versuchsbeginn keine Düngung. Die Verfahren DYN, ORG und KON werden auf zwei Düngestufen geführt (2 = praxisübliche Düngung; 1 = halbe praxisübliche Dündung), Verfahren MIN nur auf Düngestufe 2. Ziel der Arbeit war es eine NPK Bilanz für den DOK-Versuch zu errechnen, um eine Abschätzung des Verlustpotentials bzw. von Nährstoffmangel der Feldfrüchte im jeweiligen Bewirtschaftungssystem zu ermöglichen. Die Nährstoffbilanz errechnete sich aus dem Vergleich jährlicher Eintrag minus jährlicher Austrag pro Versuchsparzelle. Berücksichtigte Einträge für die Elemente N, P und K waren: 1) Düngung, 2) Deposition, 3) Saatgut. Für N wurde zusätzlich die 4) symbiotische N-fixierung durch Leguminosen sowie der 5) Transfer von fixiertem N zu Gräsern, basierend auf vorhergehenden Studien im DOK Versuch, geschätzt. Berücksichtigte Austräge für die Elemente N, P und K waren: 6) Entzug durch Ernteprodukte sowie 7) Auswaschungsversluste. Für die Elemente N und P wurden zusätzlich die Bodenvorräte aus jährlichen (N) oder 7-jährlichen (P) Messungen in Ober- und Unterboden errechnet und mit den Ergebnissen der Bilanzierung in Beziehung gesetzt. Die wichtigsten Parameter der Nährstoffbilanzen waren die Faktoren Düngung sowie Entzug durch Ernteprodukte, wobei in der N-Bilanz auch die symbiotische N-fixierung und deren Transfer zu Gräsern eine gewichtige Rolle spielte. Die Ergebnisse der NPK-Bilanzierung deuten auf unterschiedliche Nährstofflimitierungen sowohl im Bezug auf die Verfahren, als auch auf den unterschiedlichen Düngestufen hin. Die Resultate werden in Bezug auf eine nachhaltige Bodennutzung in verschiedenen landwirtschaftlichen Systemen diskutiert

Consequences of land use change on soil organic matter composition and C-P relationships in Amazonian Dark Earth and Acrisol.

The conversion of tropical forest for cassava cultivation is widely known to decrease the soil organic matter (OM) and nutrient contents of highly weathered soils in the tropics. Amazonian Dark Earth (ADE) might be more resistant to this process due to their historical anthropogenic amelioration with e.g. charcoal, ceramics and bones, leading to higher soil OM and nutrient concentrations. In this study, we analyzed the effect of land use change on the OM dynamics under tropical conditions and how this is related with P distribution at the microscale, using ADE and an adjacent Acrisol (ACR) as model systems

Higher than expected: Nitrogen flows, budgets, and use efficiencies over 35 years of organic and conventional cropping

Organic and conventional cropping systems differ in type and amount of nitrogen (N) inputs. In organic cropping only organic fertilizers are permitted, while both organic and mineral fertilizers are used in conventional cropping. Fertilizer type and amount can affect N use efficiency of a cropping system, but contributions via symbiotic N fixation and changes in soil N stocks are rarely quantified based on field data when computing nutrient budgets. We calculated an N budget that accounts for these contributions based on annual data records for a period of 35 years at the Swiss DOK (bio-Dynamic, bio-Organic, Konventionell) field experiment. Here, different organic and conventional cropping systems have been maintained at two fertilization levels: typical for the respective system, and half these doses (low). Controls comprise a conventional treatment receiving solely mineral fertilizers and an unfertilized treatment. At the typical level, average fertilizer N inputs were 93 (bio-dynamic), 96 (bio-organic), and 171 (conventional system) kg N ha−1 yr−1. Nitrogen output via harvested products regularly exceeded N input with fertilizers in all treatments. In each of the 7-year crop rotation periods, legumes (grass-clover ley, intercrops, soybean) were grown in three years. Their symbiotic N fixation was quantified based on 15N studies and legume N yield data. It ranged from 75 to 122 kg N ha−1 per year of the DOK experiment, was slightly reduced under low fertilization and was the main N input for most treatments. Soil surface budgets (sum of N inputs from fertilization, symbiotic fixation, seeds, and deposition minus N outputs via crop harvests) yielded balances from −31 kg N ha−1 yr−1 (in non-fertilized control) to +46 kg N ha−1 yr−1 (conventional system with typical fertilization level). Nitrogen use efficiencies (NUE; N output with harvests as % of sum of N inputs) reached values >100 % in treatments with negative balances while NUE ranged from 85 % to 99 % in treatments with positive balances. Changes in topsoil (0–0.2 m) N stocks over time ranged from −26 to +9 kg N ha−1 yr−1 and declined in both unfertilized and mineral fertilized controls, and in systems receiving animal manure at low fertilization levels. Thus, positive soil surface N balances and animal manure are needed to maintain or increase topsoil N stocks. While NUE was generally high in all cropping systems there remains a trade-off between either soil N mining at higher NUE or potential N loss to the environment at lower NUE