X-ray computed microtomography for the study of the soil-root relationship in grassland soils
(2013)
We present results from the analysis of three-dimensional X-ray computed tomography images of undisturbed soil samples in grassland sites. A strong positive correlation between root parameters and the solid surface/solid volume ratio was found. Preliminary analyses suggest that the relationship between soil structure and root patterns is related to the intensity of land management at the grassland sites, with reduced root volumes at sites with increased land use intensity.
The exploration of soil structure and its consequences for ecological functions is of prime importance for understanding of the 'critical zone.' In soils, the relationship between soil structure and plant roots—which influences water dynamics in soil—deserves special interest. With X-ray computed microtomography (micro-CT), soil structure and roots may be visualized and quantified simultaneously. We analyzed undisturbed soil samples from three grassland sites. After scanning the soil cores with an X-ray micro-CT scanner (resolution 40 µm), roots were delineated from the soil material and soil pore space by means of their X-ray grey value characteristics followed by the use of space transformation during image analyses. To determine efficacy of the X-ray micro-CT to identify roots, root volumes and surfaces were quantified with a standard root washing method showing good correspondence. A strong positive correlation between root volume and surfaces and the solid surface/solid volume ratio was found, with greater root growth in a more aggregated and porous soil. Preliminary analyses suggest that the relationship between soil structure and root patterns is related to the intensity of land management at the grassland sites, with reduced root volumes and surfaces at sites with increased land use intensity. This methodology has substantial potential for further research on management influences on soil structure and root growth across landscapes.
Injection of poly(methyl methacrylate) cements, one standard Treatment for osteoporotic vertebral body fractures, may lead to critical loads and subsequent fractures in adjacent vertebral bodies. Biodegradable calcium phosphate cements (CPC) with bioinductive growth factors may be an alternative, since they have a Young’s modulus comparable to that of cancellous bone. Non-destructive tests with μCT and quantitative Image evaluation are used to assess new bone growth and material resorption following intravertebral injection of CPC. Immediate deep-freezing of excised bone prevents shrinkage or tissue disintegration and the samples have to be kept frozen for all following steps, including transport, μCT measurements, and subsequent biomechanical tests. Here we will report on a set-up to preserve the frozen state of the material and allow stable long-term serial μCT measurements. In addition, the image processing technique for the evaluation of bone growth and selected results on subsequently carried out compressive strength tests will be presented.