Use of vetiver grass for soil and water conservation on the sloping lands. 1) A test of different vertical intervals 2) A test of different rows number and plant spacings
1999
Phithag Inthapan | Sasiprapa Poungpub | Nipon Audpoung | Sawatdee Boonchee (Land Development Dept., Bangkok (Thailand). Land Development Regional Office 6. Technical Section)
Use of vetiver grass for soil and water conservation was studied during 1993-1995. The different vertical intervals for vetiver hedges were undertaken on the slope complex soil with slopes 20 percent at Chiang Doa District, Chiang Mai Province. The results showed that all vertival intervals (1.0, 2.0 and 3.0 m) prove equally effective for erosion control. Soil erosion from these treatments were significantly lower than the farmers practice treatment. However they were not significantly different among those threatments. This indicated that the vetiver hedges for all vertical intervals from 1.0 to 3.0 metres can minimise soil erosion. Therefore, to extend the use of wider vertical intervals i.e. 2.0-3.0 metres should increase the cropping area and hence satisfy the farmers. The growth of vetiver grass in terms of tiller number and hill size were not significantly different among the treatments. There will become a permanent live fence for erosion control in the following year. The number of rows and the hills spacing of vetiver grass for erosion control were studied at the same area of the above experiment. The results indicated that, both single and double rows with three hill spacings treatments (10, 15 and 20 cm) provided very effective erosion control measures compared to farmers' practice treatment. For soil moisture conservation obervation at the site was shown that vetiver hedge treatments could slow down water run-off, and allowed more water infiltrate into the soil than the farmers' practice treatment. Therefore, vetiver hedge treatments should conserve soil moisture during the dry season more longer than the farmers practice treatments. It was also indicated that, close spacing provided more soil moisture higher than wider spacing, due to better growth performance. However, in terms of technology transfer a single row planted with 10 cm hill spacing should be recommended to farmers.
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