Measurement of hydraulic properties of growing media with the HYPROP system

Knowledge of hydro-physical properties is an essential prerequisite for assessing the suitability and quality of growing media. The method used for sample preparation is important for the measurement results. Three different sample preparation methods were compared. The methods differed in terms of the way the 250°cm3 steel cylinder was filled and the height of preloading. Measurements on loosely filled cylinders were included. The comparison was carried out on 15 growing media using the HYPROP device. HYPROP enables a complex analysis of the hydro-physical properties with high accuracy and reproducibility. The water retention curve, the unsaturated hydraulic conductivity function, the dry bulk density, the shrinkage and the rewetting properties can be measured simultaneously. The air capacity and the amount of plant-available water in pots depend on the height of the pot. In the field, it is related to the field capacity. The quality assessment was carried out both for flowerpots of different height and for field conditions with free drainage. Loosely filled samples consolidated hydraulically shortly after the start of the measurement. These geometric changes can be taken into account with the HYPROP. The sample preparation method – preloading or loose filling – yielded significantly different results for the pore volume, dry bulk density, plant available water and air capacity. The total pore volume of the loosely filled cylinders varied between 86.8 and 95.2°% by vol. (preloaded 81.3 and 87.7°% by vol.). The most critical factor was the air capacity. Loosely filled substrate samples achieved the highest air capacities, but also did not reach the critical value of 10°% by volume in shallow flowerpots, e.g. in 10 cm pots with 5.8°% by volume. The sample preparation method, measurement and quality assessment of the hydro-physical properties of growing media should be adapted to the conditions of use – whether they are used in a field with free drainage or in pots or containers in greenhouses

Microgranular fertilizer and biostimulants as alternatives to diammonium phosphate fertilizer in maize production on marshland soils in northwest Germany

The eutrophication of groundwater through widespread diammonium phosphate (DAP) fertilization and excessive farm fertilizer is one of the major problems in European agriculture. Organomineral microgranular fertilizers that have a reduced phosphorus (P) content, alone or in combination with biostimulants, offer promising alternatives to DAP fertilization. We conducted a field experiment with maize (Zea mays) on a marshland soil site in order to compare the yield increase and the phosphorus balance of DAP and microgranular fertilizer variants. P content of the soil on the study site is 3.9 g P per 100 g soil. Treatments involved a combination of two fertilizers, namely DAP or a P-reduced microgranular slow-release organomineral fertilizer (Startec) and the biostimulants mycorrhiza, humic substances and soil bacteria, applied individually or along with two of the above biostimulants. Fertilizer variants were also tested individually without additional biostimulants. One in four plots was used as a control, treated only with biogas slurry, to identify site-specific spatial variability and to implement correction factors to process raw data using standardized methods. Startec performed as well as DAP in terms of both the yield and corn cob ratio, while the P excess was lower in plots treated with Startec (av. = 4.5 kg P2O5 ha-1) compared to DAP (av. = 43.7 kg P2O5 ha-1). The latter differences are of statistical significance. Individual biostimulants and a combination of multiple biostimulants rarely resulted in significantly higher yields, with the exception of some combinations with humic substances and mycorrhiza in individual years. The influence of the climatic conditions in each of the years was higher than the influence of the biostimulants. However, average increases in yield over three years would be economically beneficial for farmers in the case of the applied humic substances product and mycorrhiza. An adequate alternative to DAP was found in the form of a Preduced microgranular fertilizer from Startec

Climate change as the driving force behind the intensification of agricultural land use

Climate change in Europe will lead to new precipitation patterns over the coming years and the annual temperature will increase significantly. These changes in climate variables and the resulting effects on agricultural productivity must be differentiated regionally. Plant production depends on sufficient rainfall in summer and, in some regions, on the amount of rainfall in winter. In Central Europe, the amount of precipitation in summer will decrease in the coming decades due to climate change, while in some regions, the amount of winter precipitation will increase significantly. Agricultural production is likely to suffer severely as a result of rising summer temperatures and low water retention capacities in the soil. The effects of reduced summer precipitation and increased air temperatures are partially offset by the expected increased CO2 concentration. Therefore, the effects that changed climatic conditions have on crop production are sometimes less drastic in terms of crop yields. The greatest impact of climate change on land use is expected from increasing evapotranspiration and lower amounts of precipitation in the production of leachate. In addition to the expected mean changes, the occurrence of extreme weather conditions is key. Periods of drought in the growing season and heavy flooding as a result of extreme rainfall are to be expected. However, these events are very difficult or even impossible to predict. In addition to the effects that climate change will have on regional crop production, global changes will have a strong impact on world markets for agricultural products. Another consequence of climate change and population growth is a higher demand for agricultural products on world markets. This will lead to dramatic local land use changes and an intensification of agriculture that will transform existing crop production systems. The intensification caused by rising land and lease prices will primarily affect the maximization of the use of fertilizers and pesticides

Time-averaged and time-resolved laser optical temperature measurements in water with Filtered Brillouin Scattering combined with LDV

A laser measuring system was developed and built that allows to optically measure temperature in water using the method of Filtered Brillouin Scattering (FBS). First time-resolved optical temperature measurements were demonstrated. Furthermore, the FBS-system was combined with an LDV to enable simultaneous measurement of flow velocity and therefore the system is also capable to measure the heat flow. Time-averaged temperature values were determined with good accuracy and, as a special highlight, also timeresolved temperature measurements have been demonstrated with temporal resolution in the order of approximately 10 ms, validated by comparison with fast thermocouple measurements. The overarching goal of the research project was to prepare the market introduction of a laser-optical measuring system for spatially point-based and time-resolved measurement of the heat flow in liquids, especially in water. In order to realize this, it was necessary to measure the local velocity and the local temperature in a liquid. The optical measurement of the local velocity has long been possible using the established method of laser Doppler velocimetry (LDV). Therefore, the heat flow measurement method to be developed should be based on this technology. Until now, there was no suitable optical method for measuring the temperature. In recent years, however, the physical phenomenon of Brillouin scattering has become one focus of measurement technology development. If a small volume of liquid is irradiated with light, the molecules in the liquid scatter back part of the light, which is known as Brillouin scattering. The spectrum of the scattered light depends on the local temperature in the liquid; and it turns out that this physical relationship can be exploited to develop a highly accurate, fast, and non-contact method for measuring temperature. In this paper, we explain the Filtered Brillouin Scattering (FBS) method, show a setup for measuring temperature and velocity in water flows and thus a method for determining the heat flow, and demonstrate the measurement accuracy using a calibration test bench. The temperature measurement accuracy achieved is in the order of 1 K

Three dispersal routes out of Africa: A puzzling biogeographical history in freshwater planarians

Aim Freshwater planarians may have a wide geographical range despite their assumed low vagility. Found across four continents, Dugesia may have either an ancient origin on a large palaeo landmass, followed by colonisation in different regions before continental fragmentation, or a more recent origin and subsequent transoceanic dispersal. We seek to resolve between these two hypotheses. Location Africa, Eurasia and Australasia. Taxon Genus Dugesia (Platyhelminthes: Tricladida: Dugesiidae). Methods We used data from the sequencing of six gene fragments and comprehensive taxonomic sampling of Dugesia from across its distribution range to reconstruct the phylogeny of this genus using maximum likelihood and bayesian inference methods. We conducted two phylogenetic dating analyses using Platyhelminthes fossils and palaeogeological events. Basing on the time-calibrated molecular phylogenetic framework we evaluated the contribution of vicariance and dispersal to the biogeographical evolution of Dugesia. By reconstructing the ancestral areas and present-day potential distribution using BioGeoBEARS and niche modelling, we elucidated the biogeographical history of the genus. Results The present-day distribution of Dugesia is a result of different vicariance and dispersal events. However, we also found evidence of transoceanic dispersal. Consistent with previous hypotheses, Dugesia dates to the Upper Jurassic in the Afro-Malagasy Gondwana region. We unveiled a novel biogeographical scenario for the genus, involving multiple events of colonisation in Eurasia from continental Africa via at least three dispersal routes. Main conclusions Dugesia is an ancient genus having reached its present distribution through a complex history of dispersal and vicariant events following its origin in southern Gondwana. Despite the low vagility of Dugesia, we found evidence of their overseas dispersal

Laseroptische Temperaturmessung in Flüssigkeiten mittels gefilterter Brillouin-Streuung

In diesem Beitrag wird ein neuartiges, laserbasiertes Messverfahren zur Erfassung der Temperatur von Flüssigkeiten vorgestellt. Das Verfahren basiert auf der temperaturabhängigen Brillouin-Streuung von Laserlicht kombiniert mit einem optischen Filter in Form molekularen Joddampfes. Das Verfahren kann beispielsweise zur örtlich und zeitlich aufgelösten Erfassung des Temperaturprofils einer Rohrströmung eingesetzt werden. Der nichtinvasive Charakter laseroptischer Messverfahren verhindert dabei die Beeinflussung des Strömungsprofils durch Sensoreinbauten. Der vorliegende Beitrag führt kurz die physikalischen Grundlagen aus, beschreibt den Einsatz eines Molekularfilters und stellt die verschiedenen Teilkomponenten des Messsystems vor. Anschließend wird mit ausgewählten Messergebnissen für stationäre und dynamische Temperaturzustände die grundsätzliche Funktionsfähigkeit des Messprinzips nachgewiesen

Prey capture and feeding behaviour in an endemic land flatworm from São Tomé Island

Thielicke, Matthias, Sluys, Ronald (2019): Prey capture and feeding behaviour in an endemic land flatworm from São Tomé Island. Journal of Natural History 53 (23): 1385-1393, DOI: 10.1080/00222933.2019.165141

On the Negative Impact of Mycorrhiza Application on Maize Plants (Zea mays) Amended with Mineral and Organic Fertilizer

Many studies describe the positive effect of mycorrhiza, but few report on negative effects. Furthermore, there is a research gap on the mechanisms under which conditions the symbiotic mycorrhizal plant interaction or a parasitic one predominates. The study was conducted as a field experiment over three years to investigate the effect of mycorrhiza (Rhizoglomus intraradices) and soil bacteria applications on fertile soil. A standard fertilizer (diammonium phosphate) and two microgranular fertilizers (mineral and organomineral) were applied alone or in combination with the biostimulants mycorrhiza and/or soil bacteria (Bacillus velezensis). The application of the mycorrhiza as the only biostimulant resulted in lower yields compared to all fertilizer variants without the mycorrhiza or with mycorrhiza in combination with soil bacteria in the dry years 2015 (p = 0.0241) and 2016 (p = 0.0003). The usage of soil bacteria alone, or soil bacteria with fertilizer, resulted in few occasional significant differences. The combination with soil bacteria raised the yield of mycorrhiza-treated fertilizer variants to a significant extent in 2015 (p = 0.0007) and 2016 (p = 0.0019). The negative effects of mycorrhiza application in this study were alleviated by the simultaneous use of soil bacteria. Treatments with organomineral microgranular fertilizer, which were expected to promote the naturally occurring soil microbiome more than the mineral fertilizer variants, were most negatively affected by the mycorrhiza. We hypothesize that the naturally occurring microbiome of the study site was already optimal for maize plants, and thus the successful introduction of other microorganisms through the application of the mycorrhiza and soil bacteria tended not to be beneficial. The present study is the first report on the negative influence of arbuscular mycorrhiza on maize yields gained with a standard fertilizer (diammonium phosphate) and two microgranular fertilizer, and the alleviation of that impact by combined application of soil bacteria. We conclude that the application of the used biostimulants may have negative impacts on maize yield if the soil is already rich in nutrients and water is the limiting factor