Paul Truong, who is currently visiting the US sent us this note from Alabama.
The owner of a restaurant in Dadphne, near Mobile, Alabama,planted vetiver to reinforce the foundation of his restaurant behind the steel plated retaining wall.From the size of the plants, this was planted about 7-8 years ago. The Vetiver planting not only held his restaurant up, it prevented the foundation sliding down the slope. Results: while the steel plates in front of the Vetiver planting remained straight, the plates on slope without V bent at least 5-8º. (the unaffected retaining wall is behind the black pole.
This is a good example of how vetiver improves the shear strength of soil.