How Does Embedding Angle Affect Root-Soil Mechanical Interactions?

Chaobo Zhang

doi:10.3390/su15043709

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How Does Embedding Angle Affect Root-Soil Mechanical Interactions?

2023-02-17

DOI：10.3390/su15043709

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Abstract

En 中文

Root-soil mechanical interactions are of vital importance in soil reinforcement by plant roots. However, it is unclear how the angles of the roots in the soil affect the root-soil mechanical interactions. To better understand the effect of this factor on root-soil mechanical interactions, pullout tests were conducted on alfalfa (Medicago sativa L.) roots with five root diameter groups (0.10-0.30 mm, 0.31-0.50 mm, 0.51-0.70 mm, 0.71-0.90 mm and 0.91-1.10 mm) and four embedding angles (30 degrees, 45 degrees, 60 degrees and 90 degrees) in sandy loam soil. Root tensile tests were also carried out to understand the process of root failure in the pullout tests. The results showed that the roots had two failure modes, slippage failure and breakage failure. The critical diameter of the two failure modes was 0.35 mm. Peak pullout force and pullout energy were positively related to the root diameter in power functions. Displacement was negatively related to the root diameter and embedding angle in exponential functions. Peak pullout force, root-soil friction coefficient and pullout energy all increased and then decreased with increasing embedding angles. The peak pullout force and root-soil friction coefficient reached their maximum values under an embedding angle of 60 degrees, and pullout energy reached the maximum value under an embedding angle of 45 degrees. Pullout energy was suggested as a preferred index of root-soil mechanical interactions for both thick/fine roots and inclined/upright roots.

Keywords:

root-soil interaction

embedding angle

peak pullout force

root-soil friction coefficient

pullout energy