High-resolution synchrotron imaging shows that root hairs influence rhizosphere soil structure formation

In this paper, we provide direct evidence of the importance of root hairs on pore structure development at the root-soil interface during the early stage of crop establishment. This was achieved by use of high resolution (~5 μm) synchrotron radiation computed tomography (SRCT) to visualise both the structure of root hairs and the soil pore structure in plant-soil microcosms. Two contrasting genotypes of barley (Hordeum vulgare L.), with and without root hairs, were grown for 8 days in microcosms packed with sandy loam soil at 1.2 g cm-3 36 dry bulk density. Root hairs were visualised within air filled pore spaces, but not in the fine-textured soil regions. - We found that the genotype with root hairs significantly altered the porosity and connectivity of the detectable pore space (> 5 μm) in the rhizosphere, as compared with the no-hair mutants. Both genotypes showed decreasing pore-space between 0.8 mm and 0.1 mm from the root surface. Interestingly the root-hair-bearing genotype had a significantly greater soil pore volume-fraction at the root-soil interface. - Effects of pore structure on diffusion and permeability were estimated to be functionally insignificant under saturated conditions when simulated using image based modelling

Tempo de uso em pastagens e volume dos macroporos do solo na Amazônia Central

Soil quality under usage through time, and within agroecosystems, is an important aspect in order to improve soil usage sustainability in tropical regions. In this scenario, quantifying the effects of time of usage in pastures under the different soil components (macropores) is important to determine the management planning and reclamation most adequate for such areas. The objective of this study was to evaluate the time effect in pastures (4, 5 and 8 years) on macropore volume after ten years of abandonment and nine of reclamation through Capoeira and agroecosystems. Macropore volume was measured in three different depths (0-5; 5-10 and 10-15 cm) in 100 cm3 steel cylinders. Macropore volume dropped significantly with the raise in time usage of the areas as pasture, which in turn makes time usage evident in pastures over macropore volume of soil ≥ 50μ μm, mainly in the first soil layer (0-5 cm), directly affected by animal impact. Therefore, it is suggested that time of soil reclamation should be longer than ten years so that the soil characteristics can be recovered