1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology

Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

1.3 Conditions regarding the use of data documented through WOCAT

The compiler and key resource person(s) accept the conditions regarding the use of data documented through WOCAT:

Yes

1.5 Reference to Questionnaire(s) on SLM Approaches (documented using WOCAT)

Self teaching [South Africa]

Learning how to use vetiver grass as a vegetative conservation barrier through instructions from a booklet and hands-on practical experience.

• Compiler: Philippe Zahner
• 01/15/2009 midnight

2.1 Short description of the Technology

Definition of the Technology:

Contour lines of vetiver grass planted within fields of sugar cane, on stream banks and roadsides, to act as ‘hedges against erosion’.

2.2 Detailed description of the Technology

Description:

This example of vetiver grass barriers comes from a commercial farm in Kwa-Zulu Natal, South Africa, where sugar cane is grown on a large scale under a rainfall regime of around 1,000 mm per year. Vetiver grass (Vetiveria zizanioides), which had been growing naturally on the farm for years in isolated clumps, began to be used in 1989 to form vegetative hedges along the contour.
The purpose of these hedges is to protect the land from surface erosion by creating semi-permeable barriers, allowing excess runoff to filter through but holding back sediment. Infiltration is thus increased and moisture conserved in-situ. Although sugar cane in itself protects the soil quite well when the canopy is closed, after harvest on the moderate to steep slopes (10% to >30%) and erodible soils of the north coast of Kwa-Zulu Natal, extra protection is required. The vetiver system is supplemented by other soil conservation measures such as strip cropping, terraces, mulching and minimum tillage – all of which are used to some extent on this farm. Vetiver also helps by permanently marking the contour line, which then guides land preparation. In common with other vegetative barriers, vetiver lines lead to the formation of terraces over time, through the effect of tillage and water erosion between the strips.
Vetiver clumps are dug up and separated into slips (tillers), cut to a length of 10 cm and then planted 10–15 cm apart along the contour, also by stream banks, and by roadsides, just before the rains. This ensures good establishment. Single lines are used in this farm, though double lines are more effective at creating a hedge, and are the normal recommendation. Work starts at the top of the slope, and continues downwards. The cross-slope grass hedges are sited at 5 m vertical intervals on slopes of more than 10%, in lines about 200 m long. The cost of vetiver grass planting depends very much on slope (and thus the number of lines to be planted), availability of materials and labour.
Maintenance is very important, as vetiver often requires ‘gapping-up’ to keep the barrier dense, and it needs also to be cut back before the dry season to prevent it burning. The cut material can be used for mulching. Vetiver is poorly palatable, and therefore not useful as fodder. The maximum height of a vetiver hedge is kept down to approximately 50 cm. This minimises shading and competition, keeps the fire risk low, increases tillering (for production of vegetative splits) and ensures adequate density.

2.3 Photos of the Technology

2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment

Country:

South Africa

Region/ State/ Province:

KwaZulu/Natal

Further specification of location:

Lower Tugela district

Specify the spread of the Technology:

• evenly spread over an area

If the Technology is evenly spread over an area, specify area covered (in km2):

8.0

If precise area is not known, indicate approximate area covered:

• 1-10 km2

Comments:

Total area covered by the SLM Technology is 8 km2.

The vetiver system has been applied on my own properties. Neighbouring farms have adopted other methods of conserving the soil. i.e. vegetative, agronomic and structural in various combinations (= farm)

Map

×

2.6 Date of implementation

If precise year is not known, indicate approximate date:

• less than 10 years ago (recently)

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• during experiments/ research

Comments (type of project, etc.):

The grass originally came to this country from Mauritius.

3.1 Main purpose(s) of the Technology

• reduce, prevent, restore land degradation

3.2 Current land use type(s) where the Technology is applied

Cropland

• Perennial (non-woody) cropping

Perennial (non-woody) cropping - Specify crops:

• sugar cane

Number of growing seasons per year:

• 1

Specify:

Longest growing period in days: 200; Longest growing period from month to month: Oct - April

Comments:

Major cash crop: sugar cane

Major land use problems (compiler’s opinion): The steep topography and shallow soils limit the types of land use possible e.g.. perennial grass cover (sugarcane or grazing) or commercial timber production. Annual cropping is not possible without major alteration to the landscape e.g. terracing.

3.4 Water supply

Water supply for the land on which the Technology is applied:

• rainfed

3.5 SLM group to which the Technology belongs

• improved ground/ vegetation cover
• cross-slope measure

3.6 SLM measures comprising the Technology

vegetative measures

• V5: Others

Comments:

Main measures: vegetative measures

Secondary measures: agronomic measures, structural measures, management measures

Specification of other vegetative measures: grass strip as hedges

Type of agronomic measures: mulching, minimum tillage, contour ridging

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

• Wt: loss of topsoil/ surface erosion
• Wg: gully erosion/ gullying

soil erosion by wind

• Et: loss of topsoil

water degradation

• Hg: change in groundwater/aquifer level

3.8 Prevention, reduction, or restoration of land degradation

Specify the goal of the Technology with regard to land degradation:

• reduce land degradation
• restore/ rehabilitate severely degraded land

Comments:

Secondary goals: rehabilitation / reclamation of denuded land

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Vetiver grass is planted as a vegetative barrier (hedge), on the contour at 5 metre vertical intervals within fields of sugarcane.

Location: Lower Tugela district. KwaZulu/Natal

Technical knowledge required for field staff / advisors: low

Technical knowledge required for land users: low

Main technical functions: control of dispersed runoff: impede / retard

Secondary technical functions: control of concentrated runoff: impede / retard, increase / maintain water stored in soil

Mulching
Material/ species: Sugarcane
Remarks: Full ground cover

Minimum tillage
Material/ species: Chemical crop eradication

Contour ridging
Material/ species: Planting lines ridged on contour

Vegetative measure: contour
Vegetative material: G : grass
Vertical interval between rows / strips / blocks (m): 5
Spacing between rows / strips / blocks (m): 2
Vertical interval within rows / strips / blocks (m): 0
Width within rows / strips / blocks (m): 0.5

Vegetative measure: Vegetative material: G : grass

Grass species: Vetiver grass

Slope (which determines the spacing indicated above): 20.00%

If the original slope has changed as a result of the Technology, the slope today is (see figure below): 20.00%

Gradient along the rows / strips: 0.00%

Other type of management: Cane is planted on suitability (slope, soil depth)

Author:

Marie Joseph Maxime Robert

4.2 General information regarding the calculation of inputs and costs

Specify how costs and inputs were calculated:

• per Technology area

Specify currency used for cost calculations:

• USD

4.3 Establishment activities

4.4 Costs and inputs needed for establishment

Comments:

Duration of establishment phase: 24 month(s)

4.5 Maintenance/ recurrent activities

4.6 Costs and inputs needed for maintenance/ recurrent activities (per year)

Comments:

Machinery/ tools: 1 hoe

1) Labour,
2) Transport,
3) Price of grass,
4) Fertiliser,
5) Equipment

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

1) Labour,
2) Transport from nursery to field,
3) The steeper the gradient the more contour lines of vetiver grass will be used,
4) Fertiliser

5.1 Climate

5.2 Topography

Comments and further specifications on topography:

Slopes on average: Also moderate, mostly in footslopes & valleys (steep sides)

Landforms: Also ridges

Altitudinal zone: 360 - 380 m a.s.l.

5.3 Soils

If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.

Soil depth on average: Als very shallow. But mostly moderately deep

Soil texture: Mostly medium

Soil fertility is medium

Topsoil organic matter: Mostly medium and high in very small areas

Soil drainage / infiltration is good - medium

Soil water storage capacity is medium - high

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Market orientation of production system: All commercial

Level of mechanization: Manual labour for fertilising, weeding, planting, harvesting and mechanised for crop extraction

5.7 Average area of land used by land users applying the Technology

5.8 Land ownership, land use rights, and water use rights

Land ownership:

• individual, not titled

Land use rights:

• individual

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Income and costs

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

Soil

Climate and disaster risk reduction

Other ecological impacts

6.2 Off-site impacts the Technology has shown

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?

6.5 Adoption of the Technology

• > 50%

If available, quantify (no. of households and/ or area covered):

3 households

Of all those who have adopted the Technology, how many did so spontaneously, i.e. without receiving any material incentives/ payments?

• 91-100%

Comments:

100% of land user families have adopted the Technology without any external material support

3 land user families have adopted the Technology without any external material support

Comments on spontaneous adoption: estimates

There is a little trend towards spontaneous adoption of the Technology

Comments on adoption trend: Some local growers are experimenting with the vetiver system or with vetiver grass used in other applications (gullies, road embankments, etc.)

6.7 Strengths/ advantages/ opportunities of the Technology

6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them

7.1 Methods/ sources of information