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)

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)

Regional rural development programme [Spain]

Regional development programme to protect natural resources and stimulate rural economies.

• Compiler: Joris De Vente
• 05/12/2009 midnight

2.1 Short description of the Technology

Definition of the Technology:

Earth-banked terraces in cereal and almond cropland covered with drought-resistant shrubs.

2.2 Detailed description of the Technology

Description:

Earth-banked terraces are constructed by carefully removing a superficial soil layer (~10-20 cm) from one part of a field, concentrating it on the lower end of that field in order to reduce slope gradient and length. Another terrace is created directly downslope to form a cascade of terraces. Terrace risers have to be of restricted height (~50-150 cm) to prevent steep and unstable terraces. Stones from the fields can be used to reinforce the terrace ridge. After terrace construction, fields should be gently sloping (<3%) in the direction of the main slope. The distance between terraces must be enough to allow tractor movement during normal cultivation activities and it depends also on the slope gradient. The steeper the slope, the shorter is the distance between terraces. Terraces reduce the formation of gullies and retain water from upslope. The terraces are made with locally available machinery (tractor, small bulldozer). The terrace ridges are optimal locations to plant olives, almonds or fruit trees. Moreover, to be most effective, the terrace ridges are vegetated with shrubs adapted to semi-arid conditions and with a good surface cover (>~30%) throughout the year (e.g. Stipa tenacisima, Rosmarinus officinalis, Thymus vulgaris, Ulex parviflorus, Rhamnus lycioides, Pistacia lentiscus). Natural regeneration of vegetation is allowed without limitation on the terrace ridges, so no herbicide application or burning are carried out to remove weeds. Where possible, regeneration should be stimulated by planting the same adapted species in at least 25% of the terrace ridge. Optionally, in the other 75% of the terrace ridge, cereals or other leguminous species can be sown, but should not be harvested or used for grazing.

Purpose of the Technology: This technology reduces flooding, damage to infrastructure and siltation of water reservoirs, while maintaining (or slightly increasing) crop productivity. This is achieved by reducing runoff, soil erosion and hydraulic connectivity through a decreased slope gradient and an increased vegetation cover. The terrace ridge functions as a sink for runoff within fields and reduces runoff velocity. The vegetation leads to increased soil organic matter content below plants, producing an improved soil structure and a higher infiltration capacity. The use of stones from the fields to reinforce the terraces is optional, but facilitates crop production in the fields and makes the ridges more resistant to higher runoff velocities. The technology requires an initial investment in the construction of the terraces. Terraces can best be located on thalwegs and on areas where gully formation is often observed. Maintenance consists of filling up possible bank gullies developed in the terraces after important rainfall events and, if needed, substitute decayed shrubs with new ones.

Natural / human environment: The technology is generally applied on soils of shallow to medium depth (20 – 60 cm), and slopes are gentle to moderate (5-15%). The climate is semi-arid with a mean annual rainfall around 300 mm. Droughts, peaking in summer commonly last for more than 4-5 months. Annual potential evapotranspiration rates larger than 1000 mm are common. The production system is highly mechanized and market-oriented but depends strongly on agricultural subsidies. All cropland is privately-owned.

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:

Spain

Region/ State/ Province:

Murcia

Further specification of location:

Guadalentin catchment

Specify the spread of the Technology:

• evenly spread over an area

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

• 10-100 km2

Map

×

2.6 Date of implementation

If precise year is not known, indicate approximate date:

• more than 50 years ago (traditional)

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• as part of a traditional system (> 50 years)

Comments (type of project, etc.):

Most of the earthen terraces are already much older than 50 years. Recently, the regional administration is promoting clearly defined vegetated strips with minimum dimensions in order to apply for subsidies.

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

Land use mixed within the same land unit:

Yes

Specify mixed land use (crops/ grazing/ trees):

• Agroforestry

Cropland

• Annual cropping
• Tree and shrub cropping

Tree and shrub cropping - Specify crops:

• tree nuts (brazil nuts, pistachio, walnuts, almonds, etc.)

Number of growing seasons per year:

• 1

Specify:

Longest growing period in days: 220Longest growing period from month to month: November to June

Grazing land

Forest/ woodlands

• (Semi-)natural forests/ woodlands

Comments:

Major land use problems (compiler’s opinion): A lack of water availability seriously limits the production potential of the soil and results in a low vegetation/crop cover. The relatively high soil erosion rates cause various off-site related problems (i.e. flooding, reservoir siltation) and on-site problems (i.e. gully formation and loss of soil depth).

Major land use problems (land users’ perception): Lack of water for irrigation of crops limiting the crop types that can be planted as well as the crop yield of dryland farming.

Number of growing seasons per year:

1

Specify:

Longest growing period in days: 220Longest growing period from month to month: November to June

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

• V1: Tree and shrub cover
• V2: Grasses and perennial herbaceous plants

structural measures

• S1: Terraces

Comments:

Main measures: vegetative measures, structural measures

Type of vegetative measures: aligned: -contour

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
• Wo: offsite degradation effects

water degradation

• Ha: aridification

Comments:

Main type of degradation addressed: Wt: loss of topsoil / surface erosion, Wg: gully erosion / gullying, Wo: offsite degradation effects

Secondary types of degradation addressed: Ha: aridification

Main causes of degradation: crop management (annual, perennial, tree/shrub) (Almond and cereal fields often have a relatively low surface cover by vegetation during long periods of the year, leaving the soil unprotected against raindrop impact and rill or gully formation), disturbance of water cycle (infiltration / runoff) (Reduced infiltration capacity causing runoff and soil erosion), other human induced causes (specify) (Cropping of relatively steep slopes sensitive to erosion because of slope gradient), governance / institutional (spatial planning of land use results in formation of too large fields without field boundaries)

Secondary causes of degradation: Heavy / extreme rainfall (intensity/amounts) (High intensity erosive rainfall is common), droughts (Dry periods and dry years require higher water availability)

3.8 Prevention, reduction, or restoration of land degradation

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

• prevent land degradation
• reduce land degradation

Comments:

Main goals: prevention of land degradation, mitigation / reduction of land degradation

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Quickbird satellite image showing the concentration of terraces along natural drainage lines (thalwegs) where runoff concentrates. Drainage lines are indicated with dotted lines.

Location: Torrealvillla. Murcia

Date: Satellite image 2003

Technical knowledge required for field staff / advisors: moderate (Design of the terraces and selection of the location requires some technical knowledge.)

Technical knowledge required for land users: low (Practical implementation of the terraces does not require a high level of knowledge)

Main technical functions: control of dispersed runoff: retain / trap, control of dispersed runoff: impede / retard, control of concentrated runoff: retain / trap, control of concentrated runoff: impede / retard, reduction of slope angle, increase of infiltration, increase / maintain water stored in soil

Secondary technical functions: reduction of slope length, improvement of ground cover, stabilisation of soil (eg by tree roots against land slides), increase in organic matter, water harvesting / increase water supply, sediment retention / trapping, sediment harvesting, spatial arrangement and diversification of land use

Aligned: -contour
Vegetative material: F : fruit trees / shrubs
Number of plants per (ha): 42
Vertical interval between rows / strips / blocks (m): 1
Spacing between rows / strips / blocks (m): 30-100
Vertical interval within rows / strips / blocks (m): 0.5-7
Width within rows / strips / blocks (m): 2

Vegetative measure: alligned: contour
Vegetative material: G : grass
Number of plants per (ha): >30% cover
Vertical interval between rows / strips / blocks (m): 1
Spacing between rows / strips / blocks (m): 30-100
Vertical interval within rows / strips / blocks (m): 0.5
Width within rows / strips / blocks (m): 2

Vegetative measure: Vegetative material: G : grass

Vegetative measure: Vegetative material: G : grass

Vegetative measure: Vegetative material: G : grass

Fruit trees / shrubs species: natural regeneration of shrubs with possible additional plantation of almond trees and/or woody shru

Grass species: Natural regeneration assisted by seeding of legiminous species and cereals

Slope (which determines the spacing indicated above): 10.00%

Terrace: forward sloping
Vertical interval between structures (m): 1
Spacing between structures (m): 30-100
Height of bunds/banks/others (m): 0.5-1.5
Width of bunds/banks/others (m): 2
Length of bunds/banks/others (m): 50-200

Construction material (stone): Only when many stones are present in the fields

Slope (which determines the spacing indicated above): 5-15%

If the original slope has changed as a result of the Technology, the slope today is: <3%

Lateral gradient along the structure: 0%

Vegetation is used for stabilisation of structures.

Author:

Joris de Vente

4.2 General information regarding the calculation of inputs and costs

other/ national currency (specify):

EURO

If relevant, indicate exchange rate from USD to local currency (e.g. 1 USD = 79.9 Brazilian Real): 1 USD =:

0.63

4.3 Establishment activities

4.4 Costs and inputs needed for establishment

Comments:

Duration of establishment phase: 12 month(s)

4.5 Maintenance/ recurrent activities

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

Comments:

Machinery/ tools: For initial construction a large tractor or small bulldozer is required. For maintanance a normal tractor can be used.

The costs were indicated assuming a distance between terraces of 50 meter, meaning two terraces of 100 meter long per hectare. Prices are for spring 2008. Subsidies are foreseen for the installation of the vegetated terraces and for maintenance during at least 4 years if all requirements are fullfilled that are described in the regional development programme.

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Price of fuel and labour are the most important determinants of the costs.

5.1 Climate

5.2 Topography

Indicate if the Technology is specifically applied in:

• concave situations

Comments and further specifications on topography:

Landforms: Hill slopes-footslopes (mostly on concave slope segments)

5.3 Soils

5.4 Water availability and quality

Comments and further specifications on water quality and quantity:

Ground water table: >50m (There is a lowering of groundwater table due to overexploitation for irrigation purposes)
Availability of surface water: Poor/none (excess: sporadically there are flash floods during extreme rainfall events)
Water quality (untreated): For agricultural use only (irrigation) (groundwater)

5.5 Biodiversity

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Land users applying the Technology are mainly common / average land users

Difference in the involvement of women and men: Traditionally most agriculture is done by men in this region.

Population density: 10-50 persons/km2

Annual population growth: < 0.5%

15% of the land users are rich and own 20% of the land.
80% of the land users are average wealthy and own 75% of the land.
5% of the land users are poor and own 5% of the land.

Off-farm income specification: There is no difference in the ones who apply the technology and those who don’t. Most farmers do have an off-farm income for example from hunting, work in a factory, or office.

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, titled

Land use rights:

• individual

Water use rights:

• individual

Comments:

All cropland is privately owned. Some shrubland or forest is state property. Water use is organised by permits to water extraction from aquifers on individual basis. Water rights are provided and controlled by the Water authority of the Segura river basin (CHS).

5.9 Access to services and infrastructure

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

Biodiversity: vegetation, animals

6.2 Off-site impacts the Technology has shown

6.3 Exposure and sensitivity of the Technology to gradual climate change and climate-related extremes/ disasters (as perceived by land users)

Gradual climate change

Gradual climate change

Comments:

The crop type is sensitive to changes in water availability under the semi arid conditions

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)?

Comments:

Implementation of the terraces is relatively expensive. Additionally planting of shrubs is also relatively expensive and requires a subsidy. Once installed, maintenance is not expensive and pays off because of less damage to fields and infrastructure.

6.5 Adoption of the Technology

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

• 11-50%

Comments:

80% of land user families have adopted the Technology with external material support

Comments on acceptance with external material support: Terraces are traditionally widespread in the region. Most of them were installed without external support. Nowadays there are subsidies for construction and maintenance of vegetated strips and terraces.

20% of land user families have adopted the Technology without any external material support

There is no trend towards spontaneous adoption of the Technology

Comments on adoption trend: There is acceptance, but it is not growing. In some parts terraces are removed to make larger fields, and some new ones are also constructed. Recently installed subsidies may change this

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

7.2 References to available publications

Title, author, year, ISBN:

Garcia-Fayos, P. and Gasque, M., 2002. Consequences of a severe drought on spatial patterns of woody plants in a two-phase mosaic steppe of Stipa tenacissima L. Journal of Arid Environments, 52(2): 199-208.

Available from where? Costs?

internet

Title, author, year, ISBN:

Hooke, J.M., 2006. Human impacts on fluvial systems in the Mediterranean region. Geomorphology, 79(3-4): 311-335.

Available from where? Costs?

internet

Title, author, year, ISBN:

Kirkby, M.J., Bracken, L.J. and Shannon, J., 2005. The influence of rainfall distribution and morphological factors on runoff delivery from dryland catchments in SE Spain. CATENA, 62(2-3): 136-156.

Available from where? Costs?

internet

7.3 Links to relevant online information

Title/ description:

CARM 2008. Programa de Desarrollo Rural de la Región de Murcia 2007-2013 Tomo I. 508pp

URL:

http://www.carm.es/neweb2/servlet/integra.servlets.ControlPublico?IDCONTENIDO=4689&IDTIPO=100&RASTRO=c431$m1219