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Technologies
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Water Harvesting & Basin tillage [South Africa]

In-field water harvesting technique

technologies_968 - South Africa

Completeness: 59%

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:
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1.3 Conditions regarding the use of data documented through WOCAT

When were the data compiled (in the field)?

04/12/2001

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

2. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

In-field water harvesting technique

2.2 Detailed description of the Technology

Description:

The technique consists of the construction of a 1 m wide basin with a 2 m wide runoff area. They are mulched with either straw or stones and, for the sake of comparison, the runoff area should be left bare. The soil is not tilled to encourage development of a crust, over which water runs off into the basin.

The basins collect the maximum amount of water during rain and because it accumulates in the basin, it is allowed more infiltration time. Mulch minimises evaporation and the efficiency varies with the type of mulch used.

The construction of basin and runoff areas and mulching maintenance involves keeping basins open and mulch intact.

This technique is used under semi-arid conditions on soils with very high clay contents. The depth of the profile must be greater or equal to 900 mm and the A-horizon must also be 250 mm or more.

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:

Free State

Further specification of location:

Botshabelo, De Wetsdorp, Bloemfontein, Thaba Nchu

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.):

Other methods of water harvesting is used elsewhere in Africa.

3. Classification of the SLM Technology

3.1 Main purpose(s) of the Technology

  • adapt to climate change/ extremes and its impacts

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

Cropland

Cropland

  • Annual cropping
Main crops (cash and food crops):

major cash crop: Sunflower

major food crop: Maize

other: Beans

Comments:

Major land use problems (compiler’s opinion): The area is marginal for crop production because of relatively low and erratic rainfall and dominantly clay soils with high water losses due to runoff and evaporation from the soil surface.

Major land use problems (land users’ perception): Lack of good fertile soils and to little rain to produce a good crop.

If land use has changed due to the implementation of the Technology, indicate land use before implementation of the Technology:

Cropland: Ca: Annual cropping

3.3 Further information about land use

Water supply for the land on which the Technology is applied:
  • rainfed
Number of growing seasons per year:
  • 1
Specify:

Longest growing period in days: 120; Longest growing period from month to month: Jan - April

3.4 SLM group to which the Technology belongs

  • water harvesting

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:
  • 10-100 km2
Comments:

An area of approximately 750 000 ha east of Bloemfontein has been earmarked for developing farmers. The Water harvesting and Basin tillage technique has been employed in the scattered villages and two towns Thaba Nchu & Botshabelo.

3.6 SLM measures comprising the Technology

agronomic measures

agronomic measures

  • A6: Others
Comments:

Main measures: agronomic measures

Type of agronomic measures: mulching, mineral (inorganic) fertilizers, zero tillage / no-till

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
chemical soil deterioration

chemical soil deterioration

  • Cn: fertility decline and reduced organic matter content (not caused by erosion)
water degradation

water degradation

  • Ha: aridification
Comments:

Secondary types of degradation addressed: Wt: loss of topsoil / surface erosion, Cn: fertility decline and reduced organic matter content

Main causes of degradation: other human induced causes (specify) (Agricultural causes - Traditional, conventional cultivation methods not feasible), inputs and infrastructure: (roads, markets, distribution of water points, other, …) (Lack of knowledge)

Secondary causes of degradation: other natural causes (avalanches, volcanic eruptions, mud flows, highly susceptible natural resources, extreme topography, etc.) specify (Low and erratic rainfall events), poverty / wealth (Lack of captial - No resources to cultivate)

3.8 Prevention, reduction, or restoration of land degradation

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

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

4.1 Technical drawing of the Technology

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Author:

Cobus Botha

4.2 Technical specifications/ explanations of technical drawing

Technical specifications

Location: Glen. Free State

Technical knowledge required for field staff / advisors: moderate

Technical knowledge required for land users: moderate

Main technical functions: reduction of slope angle, increase of infiltration, increase / maintain water stored in soil, water harvesting / increase water supply

Mulching
Material/ species: Stone/straw
Remarks: <80 % stone; straw varies

Mineral (inorganic) fertilizers
Material/ species: N, P, K
Remarks: Basins/runoff areas

Zero tillage / no-till
Material/ species: Basins/runoff areas

4.6 Maintenance/ recurrent activities

Activity Type of measure Timing/ frequency
1. Preparation of basins Agronomic Before planting / Once in 10 years7
2. Preparing seed bed Agronomic At planting / annual

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
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.

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):
  • fine/ heavy (clay)
Topsoil organic matter:
  • medium (1-3%)
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 fertility is low

Soil drainage / infiltration is poor

Soil water storage capacity is high

5.6 Characteristics of land users applying the Technology

Market orientation of production system:
  • subsistence (self-supply)
  • mixed (subsistence/ commercial
Off-farm income:
  • less than 10% of all income
Relative level of wealth:
  • poor
Level of mechanization:
  • manual work
  • animal traction
Indicate other relevant characteristics of the land users:

100% of the land users are poor and own 100% of the land.

Market orientation of production system: Also commercial/ market but less common

Level of mechanization: Also mechanized, but less common

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

6. Impacts and concluding statements

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

crop production

decreased
increased

Socio-cultural impacts

conflict mitigation

worsened
improved

Ecological impacts

Water cycle/ runoff

surface runoff

increased
decreased
Quantity before SLM:

19

Quantity after SLM:

0

Soil

soil moisture

decreased
increased

soil loss

increased
decreased
Quantity before SLM:

22.6

Quantity after SLM:

9

6.4 Cost-benefit analysis

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

positive

Long-term returns:

very positive

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

positive

Long-term returns:

positive

6.5 Adoption of the Technology

Comments:

There is a moderate trend towards spontaneous adoption of the Technology

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
Can obtain higher crop yields in dry seasons.
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Minimize runoff and evaporation losses.
More water available for plant growth that leads to higher yields.
Save on input costs (Use no-till).
Unemployed people in rural semi-arid areas can produce food for themselves.

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?
Initially labour intensive to construct basins.
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
Some soil movement into the basins.
Organic mulch may absorb some rainwater.

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