Use of Vetiver for Soil Erosion Control and Better Water Quality in Farm Ponds in Salt Affected Sandy Areas of Northeast, Thailand

Abstract: On sandy and saline soils, erosion can take place easily and drastically. For the steep slopes of farm pond banks, eroded sediments that get into farm ponds can make the pond shallower with low quality water. The objective of this research was to investigate the role of vetiver in reducing the quantities of sediments and nutrients entering into farm ponds in salt affected sandy soil of Northeast Thailand. In this experiment, various rows of vetiver from 0 to 3 were established along the inner side of the steep pond bank with more than 100 % slope. Songkhla-3 ecotype was planted with spacing of 30 cm between rows and 10 cm between plants. Results indicated that the ratio of sediment collected from 0:1:2:3 rows of vetiver plots was 4:3:2:1 respectively. Planting at least 2 rows of vetiver was found to be satisfactory in reducing soil sediments hence decreased soil erosion, which resulted in better water quality under sandy and saline soils of Northeast Thailand. In relation to nutrients leached into the ponds, nitrogen, phosphorus and potassium concentrations in the soil sediments were not significantly different among the treatments. However, nutrient loss varied according to sediment dry weights, i.e. nutrient loss increased with the quantity of sediment. Planting 3 rows of vetiver reduced nutrient loss into the pond effectively