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Technologies
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Chemical bush control [South Africa]

Chemical bush control with special reference to thinning and clearing

technologies_1375 - South Africa

Completeness: 73%

1. General information

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

Key resource person(s)

SLM specialist:

Richter Chris

Department of Agriculture, South Africa

South Africa

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Department of Agriculture of Zambia (Department of Agriculture) - Zambia

1.3 Conditions regarding the use of data documented through WOCAT

When were the data compiled (in the field)?

12/12/2003

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

Yes

2. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

To either clear or thin bush (trees) in encroached areas by chemical means.

2.2 Detailed description of the Technology

Description:

In some areas, the bushes are so dense (more than 2000 plants/ha) that access to the area is not possible and therefore the aerial application of chemicals is the only solution. All the plants in this area get treated this way, but no selective treatment is possible (this is still a problem to overcome). This aerial application can be selective to some extent because some bushes survive the treatment. If that is the case, selected thinning with chemical bush control can be done on bushes (but not on palatable/usable species).
The purpose was to characterise and control bush encroachment; to define and quantify grass-bush interactions in mixed savannahs, by chemical bush control; to be able to make recommendations for larger application chemical bush control like by aerial application. There was a lack of a technique for economic comparison between the potential loss of income due to bush encroachment and the cost of controlling bush.
Aftercare is very important and is an on-going process. After the first application of the chemicals, it is possible to let in goats. Browsers are better than game, because they browse the small bushes and prevent the area from further bush encroachment. The application of fire is also possible. In this area it should only be done every 7th -10th year (depending on the rainfall and grass production). There is very little communal land in this large area (5 million ha).

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:

North West Province & Northern Cape

Further specification of location:

Vryburg, Griekwastad, Mafekeng

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:
  • through projects/ external interventions
Comments (type of project, etc.):

Started as a research project by the Department of Agriculture in the middle - late sixties and have been updated since the eighties.

3. Classification of the SLM Technology

3.1 Main purpose(s) of the Technology

  • Improve access to land

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

Grazing land

Grazing land

Extensive grazing land:
  • Ranching
Main animal species and products:

Cattle, sheep

Comments:

Major land use problems (compiler’s opinion): The negative impact that bush encroachment has on the production and botanical composition of the grass layer in these areas - thus making economical farming impossible.

Major land use problems (land users’ perception): The negative impact that bush encroachment has on the production and botanical composition of the grass layer in these areas - thus making economical farming impossible.
In the small communal areas camps are not used, the area is overstocked.

Ranching: Cattle, sheep

Grazingland comments: A definite shift to game farming and production. Grazing capacity is 10 ha/LSU. Economic farm unit perceived as to be not smaller than 3000 ha.

Type of grazing system comments: A definite shift to game farming and production. Grazing capacity is 10 ha/LSU. Economic farm unit perceived as to be not smaller than 3000 ha.

3.3 Further information about land use

Number of growing seasons per year:
  • 1
Specify:

Longest growing period in days: 180; Longest growing period from month to month: Oct - Apr

3.4 SLM group to which the Technology belongs

  • Tap/deploy land

3.5 Spread of the Technology

Specify the spread of the Technology:
  • evenly spread over an area
If the Technology is evenly spread over an area, indicate approximate area covered:
  • 100-1,000 km2
Comments:

Total area covered by the SLM Technology is 1.4 m2.

The developed technology, bush cleaning & control, will be applied on +- 5 million ha. * The technologies assist of thinning, cleaning & eradication

3.6 SLM measures comprising the Technology

vegetative measures

vegetative measures

  • V3: Clearing of vegetation

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

soil erosion by water

  • Wt: loss of topsoil/ surface erosion
water degradation

water degradation

  • Ha: aridification
Comments:

Secondary types of degradation addressed: Wt: loss of topsoil / surface erosion

Main causes of degradation: over-exploitation of vegetation for domestic use (Decrease in game led to over utilising of grass and under utilisation of woody species.), education, access to knowledge and support services (Lack of knowledge - Farmers didn't realise that they were causing the problem by not management correctly the veld)

Secondary causes of degradation: overgrazing (Especially new & around water), other natural causes (avalanches, volcanic eruptions, mud flows, highly susceptible natural resources, extreme topography, etc.) specify (Limiting of natural fires)

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: mitigation / reduction of land degradation

4. Technical specifications, implementation activities, inputs, and costs

4.1 Technical drawing of the Technology

Author:

Chris Richter

4.2 Technical specifications/ explanations of technical drawing

Technical knowledge required for field staff / advisors: moderate

Technical knowledge required for land users: moderate

Main technical functions: improvement of ground cover

Secondary technical functions: control of dispersed runoff: retain / trap, increase / maintain water stored in soil

4.3 General information regarding the calculation of inputs and costs

other/ national currency (specify):

Rand

Indicate exchange rate from USD to local currency (if relevant): 1 USD =:

6.0

Indicate average wage cost of hired labour per day:

7.00

4.4 Establishment activities

Activity Type of measure Timing
1. Soil applied chemicals (tebuthiuron) Vegetative Not important, better close to rainy season

4.5 Costs and inputs needed for establishment

Specify input Unit Quantity Costs per Unit Total costs per input % of costs borne by land users
Labour Apply chemicals ha 1.0 40000.0 40000.0
Equipment Tools ha 1.0 6000.0 6000.0
Construction material chemicals, subsistence allowan ha 1.0 20000.0 20000.0
Total costs for establishment of the Technology 66000.0
Comments:

Duration of establishment phase: 12 month(s)

4.6 Maintenance/ recurrent activities

Activity Type of measure Timing/ frequency
1. Burning the veld Management / 7-10 years
2. Browsing the veld by goats Management

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

Specify input Unit Quantity Costs per Unit Total costs per input % of costs borne by land users
Labour Burning and browsing the veld ha 1.0 10000.0 10000.0
Equipment Tools ha 1.0 1500.0 1500.0
Fertilizers and biocides Chemicals, subsistence allowan ha 1.0 5000.0 5000.0
Total costs for maintenance of the Technology 16500.0
Comments:

High salary of researcher and technician are included in the costs.

4.8 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

For all 4 plots. They were working on each plot for 3 months. Travel and subsistence costs.

5. Natural and human environment

5.1 Climate

Annual rainfall
  • < 250 mm
  • 251-500 mm
  • 501-750 mm
  • 751-1,000 mm
  • 1,001-1,500 mm
  • 1,501-2,000 mm
  • 2,001-3,000 mm
  • 3,001-4,000 mm
  • > 4,000 mm
Specifications/ comments on rainfall:

The average is +-340mm

Agro-climatic zone
  • semi-arid

5.2 Topography

Slopes on average:
  • flat (0-2%)
  • gentle (3-5%)
  • moderate (6-10%)
  • rolling (11-15%)
  • hilly (16-30%)
  • steep (31-60%)
  • very steep (>60%)
Landforms:
  • plateau/plains
  • ridges
  • mountain slopes
  • hill slopes
  • footslopes
  • valley floors
Altitudinal zone:
  • 0-100 m a.s.l.
  • 101-500 m a.s.l.
  • 501-1,000 m a.s.l.
  • 1,001-1,500 m a.s.l.
  • 1,501-2,000 m a.s.l.
  • 2,001-2,500 m a.s.l.
  • 2,501-3,000 m a.s.l.
  • 3,001-4,000 m a.s.l.
  • > 4,000 m a.s.l.
Comments and further specifications on topography:

Slopes on average: All sites in the North West Province are flat and only the one site in the Northern Cape is hilly

Altitudinal zone: Duncan, 1057m, Karlsruehe 1200-1500m, Slabbertshof 1130m

5.3 Soils

Soil depth on average:
  • very shallow (0-20 cm)
  • shallow (21-50 cm)
  • moderately deep (51-80 cm)
  • deep (81-120 cm)
  • very deep (> 120 cm)
Soil texture (topsoil):
  • coarse/ light (sandy)
  • medium (loamy, silty)
Topsoil organic matter:
  • low (<1%)
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: The site in the Northern Cape is very shallow North West Province the soils are very deep

Soil texture: Coarse in the North West and medium in the Northern Cape

Soil fertility is medium- low in both areas concerned. Very sandy soils, however, and have a poor fertility

Soil drainage / infiltration is good in the North West and poor in the Northern Cape

Soil water storage capacity is low: Plexut 71 mm at a depth 2.1m

5.6 Characteristics of land users applying the Technology

Market orientation of production system:
  • commercial/ market
Off-farm income:
  • 10-50% of all income
Relative level of wealth:
  • average
Indicate other relevant characteristics of the land users:

Population density: < 10 persons/km2

Annual population growth: 1% - 2%

15% of the land users are rich and own 20% of the land (Commercial).
85% of the land users are average wealthy and own 80% of the land (Compared with other commercial farmers).

Off-farm income specification: up to 25% farmers get involved in ecotourism (trend is to more game for ecotourism and hunting)

5.7 Average area of land owned or leased by land users applying the Technology

  • < 0.5 ha
  • 0.5-1 ha
  • 1-2 ha
  • 2-5 ha
  • 5-15 ha
  • 15-50 ha
  • 50-100 ha
  • 100-500 ha
  • 500-1,000 ha
  • 1,000-10,000 ha
  • > 10,000 ha

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

Land ownership:
  • communal/ village
  • individual, not titled
Land use rights:
  • communal (organized)
  • individual

6. Impacts and concluding statements

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

fodder production

decreased
increased
Comments/ specify:

Primary production grasses, all seasons, composition changes

fodder quality

decreased
increased

animal production

decreased
increased
Comments/ specify:

With regard to woody component (game farming)

product diversity

decreased
increased
Comments/ specify:

Higher grazing capacity

land management

hindered
simplified
Comments/ specify:

Creating an open Savannah

Income and costs

farm income

decreased
increased
Other socio-economic impacts

Initial cost

high
low

Ecological impacts

Soil

soil moisture

decreased
increased
Comments/ specify:

Decrease in encroachers

soil cover

reduced
improved
Comments/ specify:

Grass density, all seasons

Biodiversity: vegetation, animals

habitat diversity

decreased
increased
Comments/ specify:

Change of habitat

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?
Short-term returns:

negative

Long-term returns:

positive

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?
Short-term returns:

neutral/ balanced

Long-term returns:

slightly positive

6.5 Adoption of the Technology

  • more than 50%
If available, quantify (no. of households and/ or area covered):

90 percent of the area

Of all those who have adopted the Technology, how many have did so spontaneously, i.e. without receiving any material incentives/ payments?
  • 0-10%
Comments:

90% of land user families have adopted the Technology with external material support

There is a strong trend towards spontaneous adoption of the Technology

Comments on adoption trend: See it is working, improvement of the veld return on the inputs

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
Improvement in grazing capacity
Improvement of veld condition and production
Accessibility
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Improvement of veld condition and production
Accessibility (because it was to dense)

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

Weaknesses/ disadvantages/ risks in the land user’s view How can they be overcome?
Very expensive
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
Under aero-application utilisable plants can be irradiated, if not adhered to directive Hand application
Very expensive

7. References and links

7.2 References to available publications

Title, author, year, ISBN:

Msc of C. Richter, Gras-bosinteraksie in die bosveldgebiede van Noord-Kaap. 1991.

Available from where? Costs?

C. Richter

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