Roots compact the surrounding soil depending on the structures they encounter.

Abstract

Contradictory evidence exists regarding whether and to which extend roots change soil structure in their vicinity. Here we attempt to reconcile disparate views allowing for the two-way interaction between soil structure and root traits, i.e. changes in soil structure due to plants and changes in root growth due to soil structure. Porosity gradients extending from the root/biopore surface into the bulk soil were investigated with X-ray µCT for undisturbed soil samples from a field chronosequence as well as for a laboratory experiment with Zea mays growing into three different bulk densities. An image analysis protocol was developed, which enabled a fast analysis of the large sample pool (n > 300) at a resolution of 19 µm. Lab experiment showed that growing roots only compact the surrounding soil if macroporosity is low and dominated by isolated pores. When roots can grow into a highly connected macropore system showing high connectivity the rhizosphere is more porous compared to the bulk soil. A compaction around roots/biopores in the field chronosequence was only observed in combination with high root/biopore length densities. We conclude that roots compact the rhizosphere only if the initial soil structure does not offer a sufficient volume of well-connected macropores.

Plant phenotyping relevance

X線µCT画像から根周辺の土壌構造・空隙率を定量化する画像解析プロトコルを開発しており、植物形態と周辺状態の取得手法が研究の中心である。

Code and data availability

The article describes X-ray µCT phenotyping of root-induced soil compaction (lab experiment with Zea mays and a field chronosequence, n>300 samples) and a custom image analysis protocol, but the supplied blocks contain no public data or code deposit, no repository URL, and no availability statement. The only supplement

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