Phacelia (Phacelia tanacetifolia Benth.) affects soil structure differently depending on soil texture

Aims: We studied the effects of Phacelia tanacetifolia, used as a cover-crop species in arable agricultural systems, upon soil structural properties in the context of two contrasting soil textures. We hypothesised there would be differential effects of the plants upon soil structure contingent on the texture.
Methods: A sandy-loam and a clay soil were destructured at a scale of 2 mm, and planted with Phacelia in a replicated pot experiment, with associated unplanted controls. X-ray Computed Tomography was used to visualise and quantify the soil pore networks in 3D.
Results: The presence of plants did not affect the aggregate size distribution for both textures during the time frame of the experiment (6 weeks). For the sandy-loam soil, porosity,
pore connectivity, and pore surface density decreased in the presence of plants, whereas for the clay, the porosity was constant, the pore-connectivity decreased, and surface density increased in the presence of plants.
Conclusions: Plants can impact the structural genesis of soil depending on its inherent textural characteristics, leading to a differential development of pore architecture in different contexts. These results have implications from an ecological perspective, in terms of the prescription of plants to remediate or condition soil structure in managed systems.