Best Plants For Erosion Control

#1 King Alfred® Dianella

#2 Nafray® Pennisetum

#3 Lucia™ Dianella

#4 Lomandra ‘Katrinus Deluxe‘

#7 Breeze® Dianella

#8 Katie Belles™ Lomandra

#9 Agapanthus

#10 Tasred® Dianella

Research Methodology

Ten large sample pots of each variety were grown and tested with a Shear Vane tester, as were samples grown in two different gardens. 29 shear vane tests were taken for each variety from the pots. The results showed all plants strengthened the soil compared to the control samples of unvegetated potting mix and soil. Increases in soil shear strength were analysed using an ANOVA test. Any variety that showed a 95% or more increase in shear strength was found to be significantly different to the unvegetated samples.

King Alfred® Dianella strengthened the soil 752%, and in this test had an undrained shear strength of 70 kPa, compared to unvegetated soil of 9 kPa. Many other varieties however, still strengthen the soil greatly. Katrinus Deluxe, a Lomandra longifolia, strengthened the soil by 366%. Some plants that are widely used in the USA and Australia, such as Liriope Evergreen Giant had much lower readings, only strengthening the soil a statistically significant 100%.

Varieties improved through breeding all strengthen the soil considerably more than their corresponding common varieties, providing evidence that plant breeding can lead to plants better suited to strengthening soil.

This data can help Engineers, Landscape Architects, and Erosion Control professionals choose plants that better strengthen the soil, and enhance erosion control of slopes, batters, stream embankments, roadsides, retaining walls, and shore lines. It will also provide a basis for future plant breeders to develop plants and turf that better strengthen the soil.