REHABILITATION OF DEGRADED PASTURES

by Bevan McLeod and Lionel Cavanagh, Monto

Aim

To revegetate an overgrazed and eroded hill with Vetiver hedges.

Problem

A very steep slope (75-80%) on a dairy farm was overgrazed, bare of vegetation and highly erodible. As a result, natural revegetation has been very slow and rainfall can not infiltrate the ground.

Normal cultivation to improve water infiltration is not practical as the slope is too steep for safe machinery operation.

The Trial

Five rows of Vetiver planted on contour line at the vertical drop between 2m and 3m. The aim was to spread and slow down runoff water to increase water infiltration and to improve the regeneration of native pasture.

Results

Despite very dry weather in the next 18 months, Vetiver established well in this very hostile environment and hedges were formed. Although there are many gaps in the hedges, regeneration of native grasses was very impressive as compared with the site where no Vetiver was planted. After 2 years there was enough regrowth that animals were allowed to graze during the summer. This practice was continued for the next 2 years and the hill is now completely grassed and both Vetiver and native grasses provided good feed for dry cows.

Results after 4 Years

Vetiver plants are about 1 m tall with basal stool about 10 - 20mm in size. Where plant population is solid a good barrier has developed with evidence of soil and debris build up on the top side.

There has been little lateral spread of the Vetiver plants. Small amount of erosion occurred where water ran through the gaps in the hedges. If the hedges were properly maintained to reduce the number of gaps, the Vetiver grass system would be more effective in revegetating steep degraded pasture.