Chrysopogon zizanioides (vetiver grass) as a potential plant for landslide bioengineering at Atok, Benguet, Philippines

Abstract

Chrysopogon zizanioides, more commonly known as vetiver grass, is being used extensively for bioengineering in several countries, to stabilise soil. This species has a fast growth rate and can hold soil through its ability to grow on steep slopes. The use of vetiver grass for bioengineering has not yet been explored in the northern Philippines, an area prone to landslides owing to steep slopes, exacerbated by an intense rain fall regime and typhoons. The aim of this study was to validate the use of vetiver grass for stabilisation of an experimental landslide area in Atok, Benguet, northern Philippines, and to monitor its growth performance under nursery conditions. A nursery has been established in Atok for the propagation of vetiver grass and other plant species, with potential for use in stabilising landslides. Three sample plots were chosen randomly. The number of new shoots and shoot length were measured every month from planting. The results show that during the early stages of growth, vetiver grass was able to develop new shoots. The longest shoot increment measured in the nursery was 65 cm and the average number of new shoots was three per pot. During the rain season, the vetiver grass was transplanted to the experimental site. The transplanted vetiver plants were monitored there and, after 2 months, the plants had shown growth and were able to produce more and longer shoots. To assess the capability of the roots to stabilise the soil, a force gauge was used on three vetiver plants and other revegetation species, to measure how strongly the roots can hold soil. The results showed that vetiver grass has a strong soil-aggregation capacity and that the roots were able to establish in the landslide within 2 months.