Influence of lime on the Ni transfer into plants

In zweijährigen Gefäßversuchen mit einem sauren, podsoligen sandigen Lehm, der mit Nickel (Ni) kontaminiert und mit steigenden Kalkgaben behandelt war, wurde der Ni-Transfer vom Boden in die Pflanzen untersucht. Es konnte gezeigt werden, dass Kalkgaben die mobile Ni-Konzentration im Boden, die Ni-Konzentration in Pflanzen und folglich den Transferfaktor signifikant vermindern. Auf der Grundlage der sigmoidalen Bolzman Gleichung wurden die Veränderungen in den Ca/Ni-Interaktionen geschätzt. Sie wird als Schätzfunktion für die Beschreibung vergleichbarer Prozesse im System Boden-Pflanze vorgeschlagen.In a two years pot experiment with a sod-podzolic, acid sandy loam, contaminated with nickel (Ni) and treated with increased lime doses, the Ni transfer from soil to plants was studied. It was shown that lime addition significantly decreased mobile Ni concentration in soil, Ni concentration in plants and consequently its transfer factor. The sigmoidal Bolzman equation estimates the range of changes in parameters of Ca and Ni interaction. It is suggested as an estimation function for the description of related processes in the soil-plant system

Dry bulk density of Gezira Vertisol as determined by X-ray computed tomography

     Soil bulk density is an important parameter indicating the aeration of the soil, the extent of its compaction, its permeability and the state of ease of tillage. It is as well important for expression of gravimetric soil moisture values as volumetric. Current measurements of soil bulk density depend on methods that, to some extent, disturb the soil. In the case of cracking soils, sampling of soil by cylinders probably results in an imprecise determination of the bulk density considering the possible bias in placing the core samplers away from large cracks. The clod method also results in siY1ificant overestimation of the field bulk density of soils because of the small sample used and hence less number of cracks accounted for.      Under continuous cultivation and cropping as practiced in the Gezira for more than 80 years, it is quite possible that the repeated wetting and drying of the soil could cause an adverse effect on soil structure that is possibly envisaged in effects on soil bulk density. X- ray computed tomography is a non-destructive imaging technique to construct a 3-dimensional image of the scanned object (Crestana et al., 1985; Hopmans et al., 1994; Phogat et ale, 1991; Rogasik et al., 1994, 1999). The computed tomogaphy scan has shown so far a consi- derable improvement in quantification of soil morphological parame- ters (Rogasik et al., 1994, 1999).      The objective of this study is to demonstrate the usefulness of the X-ray computed tomography in determination of the narrow spaced differences in the bulk density of cracking soils and to use the results  btained   to   examine   the  effects  of   continuous   cropping   on  soi

Discrimination of soil phases by dual energy x-ray tomography

Numerous soil ecological functions are influenced by soil structure through its impact on spatial and temporal distributions of soil particles, water, and air within the soil profile. The nondestructive technique of x‐ray computed tomography (CT) was used for studying soil structure. X‐ray attenuation determined for two energy levels (80 kV and 120 kV) was used to calculate distributions of water, air, and solids, as well as the voxel dry bulk density for two silt loam subsoils. The spatial resolution during scanning was 0.25 mm in the horizontal and 1 mm in the vertical direction. For different voxel sizes, the weighted mean of the derived volumetric water, air, and solid contents, and the dry bulk densities agreed with the sample's phase composition and dry bulk density obtained by weighing. The use of dual energy scanning to study the heterogeneity of soil structure and the spatial distribution of water, air, and solids is discussed

Uveal Melanoma: A European Network to Face the Many Challenges of a Rare Cancer

Uveal melanoma (UM) is the most frequent primary ocular cancer in adults, accounting for 5% of all melanomas. Despite effective treatments for the primary tumour, up to 50% of UM patients will develop metastasis, leading to a very poor prognosis and a median overall survival of 6 to 12 months, with no major improvements in the last 30 years. There is no standard oncological treatment available for metastatic UM patients, and BRAF/MEK and immune checkpoint inhibitors show disappointing results when compared to cutaneous melanoma (CM). Recent advances in biology, however, identified specific gene and chromosome alterations, potentially permitting an actively tailored surveillance strategy, and dedicated clinical studies. Being a rare cancer, UM patients have to overcome issues such as identifying referral centres, having access to information, and partnering with oncologists for specific management strategies and research priorities. Here, we describe how the EUropean Rare Adult solid CAacer Network (EURACAN) will help in addressing these challenges and accelerating international collaborations to enhance the development of innovative treatments in UM

Quantification of root water uptake in soil using X-ray Computed Tomography and image based modelling

Spatially averaged models of root-soil interactions are often used to calculate plant water uptake. Using a combination of X-ray Computed Tomography (CT) and image based modelling we tested the accuracy of this spatial averaging by directly calculating plant water uptake for young wheat plants in two soil types. The root system was imaged using X-ray CT at 2, 4, 6, 8 and 12 days after transplanting. The roots were segmented using semi-automated root tracking for speed and reproducibility. The segmented geometries were converted to a mesh suitable for the numerical solution of Richards’ equation. Richards’ equation was parameterised using existing pore scale studies of soil hydraulic properties in the rhizosphere of wheat plants. Image based modelling allows the spatial distribution of water around the root to be visualised and the fluxes into the root to be calculated. By comparing the results obtained through image based modelling to spatially averaged models, the impact of root architecture and geometry in water uptake was quantified. We observed that the spatially averaged models performed well in comparison to the image based models with <2% difference in uptake. However, the spatial averaging loses important information regarding the spatial distribution of water near the root system

Quantifying the impact of microbes on soil structural development and behaviour in wet soils

There is evidence that microbial populations play an important role in altering soil pore geometry, but a full understanding of how this affects subsequent soil behaviour and function is still unclear. In particular the role of microorganisms in soil structural evolution and its consequence for pore morphological development is lacking. Using a combination of bio-chemical measurements and X-ray Computed Tomography (CT) imaging, a temporal comparison of microscale soil structural development in contrasting soil environments was made. The aim was to quantify the effect of microbial activity in the absence of other features likely to cause soil deformation (e.g. earthworms, roots etc.) on soil structural development in wet soils, defined by changes in the soil porous architecture i.e. pore connectivity, pore shape and pore volume during a 24 week period. Three contrasting soil textures were examined and changes compared between field soil, sterilised soil and a glucose enhanced soil treatment. Our results indicate that soil biota can significantly alter their microhabitat by changing soil pore geometry and connectivity, primarily through localised gaseous release. This demonstrates the ability of microorganisms to modify soil structure, and may help reveal the scope by which the microbial-rich rhizosphere can locally influence water and nutrient delivery to plant roots