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)

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:

Ja

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

Terrace approach [China]

Highly organised campaign to assist land users in creating terraces: support and planning from national down to local level.

• Compiler: Yaolin Wang
• 01/28/2009 middernag

2.1 Short description of the Technology

Definition of the Technology:

Level bench terraces on the Loess Plateau, converting eroded and degraded sloping land into a series of steps suitable for cultivation.

2.2 Detailed description of the Technology

Description:

The Loess Plateau in north-central China is characterised by very deep loess parent material (up to 200 m), that is highly erodible and the source of most of the sediment in the lower reaches of the Yellow River.
The plateau is highly dissected by deep gullied valleys and gorges. The steep slopes, occupying 30-40% of the plateau area, have been heavily degraded by severe top soil and gully erosion. Over the whole Loess Plateau approximately 73,350 km2 of these erosion prone slopes have been conserved by terraces.
In the case study area (Zhuanglang County) the land that is suitable for terracing has been completely covered. The total terraced area is 1,088 km2, accounting for 90% of the hillsides. The terraces were constructed manually, starting at the bottom of the slopes and proceeding from valley to the ridge. The terraces comprise a riser of earth, with vertical or steeply sloping sides and an approximately flat bed (level bench). Depending on farmers preference some terrace beds are edged by a raised lip (a small earth ridge) which retains rainwater, others remain without lip. The semi-arid climate does not require a drainage system. For typical hillside terraces on slopes of 25-35% the bed width is about 3.5-5 metres with a 1-2 metre riser, involving moving about 2,000-2,500 cubic metres of soil (see table of technical specifications). Generally the risers are not specifically protected, but there may be some natural grasses growing on the upper part. The lower part of the riser is cut vertically into the original soil surface, and has no grass cover, being dry and compact. However it is not erosion-prone since it has a stable structure.
Over most of the Loess Plateau, the soil is very deep and therefore well suited to terrace construction. In addition to downstream benefits, the purpose is to create a better environment for crop production through improved moisture conservation, and improved ease of farming operations. In an average rainfall year, crop yields on terraced land are more than three times higher than they used to be on unterraced, sloping land. The implication is that terrace construction - though labour intensive - pays back in only three to four years when combined with agronomic improvements (such as applying farm yard manure and planting green manure). Some farmers try to make the best use of the upper part of terrace risers by planting cash trees or forage crops - including Hippophae rhamnoides (seabuckthorn), Caragana korshinskii (peashrub) and some leguminous grass. This is locally termed ‘terrace bund economy’. The plants stabilise the risers and at the same time provides extra benefits.

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:

China

Region/ State/ Province:

Gansu Province (Loess Plateau Region)

Further specification of location:

Zhuanglang County

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):

1080.0

Comments:

Total area covered by the SLM Technology is 1080 km2.

Map

×

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• through projects/ external interventions

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

Land use mixed within the same land unit:

Ja

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

• Agroforestry

Cropland

• Annual cropping
• Tree and shrub cropping

Annual cropping - Specify crops:

• cereals - maize
• cereals - millet
• cereals - sorghum
• legumes and pulses - peas
• root/tuber crops - potatoes

• wheat

Tree and shrub cropping - Specify crops:

• pome fruits (apples, pears, quinces, etc.)
• stone fruits (peach, apricot, cherry, plum, etc)
• tree nuts (brazil nuts, pistachio, walnuts, almonds, etc.)

Number of growing seasons per year:

• 1

Specify:

Longest growing period in days: 160Longest growing period from month to month: May to September

Comments:

major cash crops: peas
major food crops: wheat, maize, potato, millet, sorghum
perrenial tree and shrub cropping: apple, pear and peach; walnut

Major land use problems (compiler’s opinion): Cultivation of unterraced hillside slopes leads to serious soil erosion and problems of downstream sedimentation.
Loss of topsoil and rainwater in uncontrolled runoff has contributed to declining crop yields.

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

• cross-slope measure

• terraces

3.6 SLM measures comprising the Technology

structural measures

• S1: Terraces

Comments:

Main measures: structural measures

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

chemical soil deterioration

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

water degradation

• Ha: aridification

Comments:

Main type of degradation addressed: Wt: loss of topsoil / surface erosion, Wg: gully erosion / gullying, Wo: offsite degradation effects, Cn: fertility decline and reduced organic matter content, Ha: aridification

Main causes of degradation: soil management (Absence or bad maintenance of erosion control measures), other human induced causes (specify), poverty / wealth (Lack of captial), education, access to knowledge and support services (Lack of knowledge)

Secondary causes of degradation: labour availability (Lack of labour)

3.8 Prevention, reduction, or restoration of land degradation

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

• restore/ rehabilitate severely degraded land

Comments:

Main goals: rehabilitation / reclamation of denuded land

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Layout of level bench terraces on the Loess Plateau: the lower, vertical section is cut into the compacted soil. Natural grasses -
or planted grass/ shrub species - protect the more erodible and less steep upper part of the riser. The low ‘lip’ is optional.

Technical knowledge required for field staff / advisors: high

Technical knowledge required for land users: low

Main technical functions: reduction of slope angle, reduction of slope length, increase of infiltration, increase / maintain water stored in soil, water harvesting / increase water supply, retains runoff in-situ, reduces downstream flooding, reduces sediment deposition (a national/regional concern)

Structural measure: level bench terraces
Height of bunds/banks/others (m): 1-2
Width of bunds/banks/others (m): 3.5-5

Construction material (earth): loess parent material

Slope (which determines the spacing indicated above): 30%

Author:

Mats Gurtner

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: 4 month(s)

4.5 Maintenance/ recurrent activities

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

Comments:

Calculations above are based on the following situation: slopes of about 25-35%, bed width of 3.5-6 m, and a 1-2 m high riser, involving moving about 2,000-2,500 cubic metres of soil. Note: these calculations are based on several years experience in Zhuanglang: that is why they differ in some respects from the standardised table in 2.4.1.

5.1 Climate

5.2 Topography

Indicate if the Technology is specifically applied in:

• not relevant

Comments and further specifications on topography:

Slopes on average: also rolling
Altitudinal zone: 501- 2000 m a.s.l.
Landforms: Also ridges

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 fertility: low-medium
Soil drainage / infiltration: good

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Off-farm income specification: working in construction, temporary employments
Market orientation mixed (subsistence and commercial): ash crop (peas) and food crops (potatoes, wheat, maize, millet, sorghum)

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:

• state

Land use rights:

• individual

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Income and costs

Other socio-economic impacts

Socio-cultural impacts

Ecological impacts

Soil

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

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

NA

Comments:

There is no trend towards spontaneous adoption of the Technology

Comments on adoption trend: - The technology was implemented on a large scale through government initiated mass campaigns.
- The technology has generally not spontaneously spread beyond the areas developed through government intervention: the area that is suitable for terracing has been covered.
- Uncertainty over future land use rights limits the willingness of households to meet the costs of terrace construction.

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:

Terraces In China. Published By Ministry Of Water Resources Beijing, PRC.. 1989.

Title, author, year, ISBN:

Conservancy engineering budgetary estimateration. Issued by Ministry of water resources of PRC, Published by Yellow-river water conservancy publishing company, Zhengzhou, PRC. 2003.

Title, author, year, ISBN:

A Great Cause for Centuries – 50 Years in Water and Soil Conservation in China. Published by Department of Soil and Water Conservation, Ministry ofWater Resources Beijing, PRC. 2000.

Title, author, year, ISBN:

Dongyinglin, Changpiguang, Wangzhihua: Discussion on several questions onincreasing production of the terrace with two banks; Soil and Water Conservation Science and Technology in Shanxi. No. 1, p 36–37. 1990.

Title, author, year, ISBN:

Liumingquan, Zhangaiqin, Liyouhua:Pattern engineering of reconstruction the slope cropland; Soil and Water Conservation Science and Technology in Shanxi,No. 3, p 18–21. 1992.

Title, author, year, ISBN:

Liangqichun, Changfushuang, Liming: A study on drawing up budgetary estimate quota of terraced field; Bulletin of Soil andWater Conservation, Vol. 21, No. 5, p 41–44. 2001.

Title, author, year, ISBN:

Lixuelian, Qiaojiping: Synthetic technology of fertilizing and improving production on the newterrace. Terraces in China. Soil and Water Conservation Science and Technology in Shanxi, No. 3, p 13–14. 1998.