1.2 Coordonnées des personnes-ressources et des institutions impliquées dans l'évaluation et la documentation de la Technologie

Nom du ou des institutions qui ont facilité la documentation/ l'évaluation de la Technologie (si pertinent)

ISRIC World Soil Information (ISRIC World Soil Information) - Pays-Bas

Nom du ou des institutions qui ont facilité la documentation/ l'évaluation de la Technologie (si pertinent)

Department of Resources and Environmental Science, Beijing Normal University (Department of Resources and Environmental Science, Beijing Normal University) - Chine

Nom du ou des institutions qui ont facilité la documentation/ l'évaluation de la Technologie (si pertinent)

GEF/OP12 Gansu Project (GEF/OP12 Gansu Project) - Chine

1.3 Conditions relatives à l'utilisation par WOCAT des données documentées

Quand les données ont-elles été compilées (sur le terrain)?

01/03/2006

Le compilateur et la(les) personne(s) ressource(s) acceptent les conditions relatives à l'utilisation par WOCAT des données documentées:

Oui

2.1 Courte description de la Technologie

Définition de la Technologie:

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

2.2 Description détaillée de la Technologie

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 de la Technologie

2.5 Pays/ région/ lieux où la Technologie a été appliquée et qui sont couverts par cette évaluation

2.7 Introduction de la Technologie

Spécifiez comment la Technologie a été introduite: :

• par le biais de projets/ d'interventions extérieures

3.2 Type(s) actuel(s) d'utilisation des terres, là où la Technologie est appliquée

Commentaires:

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.

3.3 Informations complémentaires sur l'utilisation des terres

Approvisionnement en eau des terres sur lesquelles est appliquée la Technologie:

• pluvial

Nombre de période de croissance par an: :

• 1

Précisez:

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

3.4 Groupe de GDT auquel appartient la Technologie

• mesures en travers de la pente

• terraces

3.5 Diffusion de la Technologie

Commentaires:

Total area covered by the SLM Technology is 1080 m2.

3.6 Mesures de GDT constituant la Technologie

Commentaires:

Main measures: structural measures

3.7 Principaux types de dégradation des terres traités par la Technologie

Commentaires:

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 Prévention, réduction de la dégradation ou réhabilitation des terres dégradées

Spécifiez l'objectif de la Technologie au regard de la dégradation des terres:

• restaurer/ réhabiliter des terres sévèrement dégradées

Commentaires:

Main goals: rehabilitation / reclamation of denuded land

4.1 Dessin technique de la Technologie

4.2 Spécification/ explications techniques du dessin technique

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%

4.3 Informations générales sur le calcul des intrants et des coûts

Spécifiez la manière dont les coûts et les intrants ont été calculés:

• par superficie de la Technologie

Indiquez la monnaie utilisée pour le calcul des coûts:

• dollars US

4.4 Activités de mise en place/ d'établissement

	Activité	Type de mesures	Calendrier
1.	Contour lines are marked out using pegs to show the location for the base of each terrace wall	Structurel	-
2.	A trench is dug out along the marked line to serve as the foundation	Structurel
3.	A trench is dug out along the marked line to serve as the foundation	Structurel	-
4.	The topsoil between the pegged lines is removed and put aside	Structurel
5.	See Annex T3: alternative ways of constructing the wall/riser, bed	Structurel
6.	The wall is raised slightly higher to form a lip to retain rainwater on the	Structurel	-

4.5 Coûts et intrants nécessaires à la mise en place

	Spécifiez les intrants	Unité	Quantité	Coûts par unité	Coût total par intrant	% du coût supporté par les exploitants des terres
Main d'œuvre	Voluntary and paid (building terraces)	ha	1,0	1200,0	1200,0	97,0
Main d'œuvre	survey of labour	ha	1,0	60,0	60,0
Equipements	tools	ha	1,0	30,0	30,0	100,0
Matériaux de construction	earth	ha	1,0
Coût total de mise en place de la Technologie					1290,0

Commentaires:

Duration of establishment phase: 4 month(s)

4.6 Activités d'entretien/ récurrentes

	Activité	Type de mesures	Calendrier/ fréquence
1.	1. Repairing any collapses in the terrace wall – often caused by heavy	Structurel
2.	2. Re-levelling of the terraces where necessary. This work is usually done by hand, using shovels and two-wheel carts.	Structurel

4.7 Coûts et intrants nécessaires aux activités d'entretien/ récurrentes (par an)

	Spécifiez les intrants	Unité	Quantité	Coûts par unité	Coût total par intrant	% du coût supporté par les exploitants des terres
Main d'œuvre	Reparing terraces	ha	1,0	25,0	25,0	97,0
Equipements	tools	ha	1,0	10,0	10,0
Matériaux de construction	earth	ha	1,0
Coût total d'entretien de la Technologie					35,0

Commentaires:

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 Climat

5.2 Topographie

Indiquez si la Technologie est spécifiquement appliquée dans des:

• non pertinent

Commentaires et précisions supplémentaires sur la topographie:

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

5.3 Sols

Si disponible, joignez une description complète du sol ou précisez les informations disponibles, par ex., type de sol, pH/ acidité du sol, capacité d'échange cationique, azote, salinité, etc.

Soil fertility: low-medium
Soil drainage / infiltration: good

5.6 Caractéristiques des exploitants des terres appliquant la Technologie

Indiquez toute autre caractéristique pertinente des exploitants des terres:

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 Superficie moyenne des terres détenues ou louées par les exploitants appliquant la Technologie

5.8 Propriété foncière, droits d’utilisation des terres et de l'eau

Propriété foncière:

• état

Droits d’utilisation des terres:

• individuel

6.1 Impacts sur site que la Technologie a montrés

Impacts socio-économiques

Production

Revenus et coûts

Autres impacts socio-économiques

Impacts socioculturels

Impacts écologiques

Sols

6.2 Impacts hors site que la Technologie a montrés

6.4 Analyse coûts-bénéfices

Quels sont les bénéfices comparativement aux coûts de mise en place (du point de vue des exploitants des terres)?

Quels sont les bénéfices comparativement aux coûts d'entretien récurrents (du point de vue des exploitants des terres)?

6.5 Adoption de la Technologie

Si disponible, quantifiez (nombre de ménages et/ou superficie couverte):

NA

Commentaires:

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 Points forts/ avantages/ possibilités de la Technologie

Points forts/ avantages/ possibilités du point de vue de l'exploitant des terres
Diversification of production: terracing makes cultivation of new cash crops possible: flax (for linseed oil), pears, apples, apricots, water melon; all these give high returns and thus make terrace construction profitable.
Benefits pay back the investments after only three to four years; approx. calculated on the basis of US$ 450 extra income per annum per hectare (for wheat) vs US$ 1,200 labour investment per hectare.

Points forts/ avantages/ possibilités du point de vue du compilateur ou d'une autre personne ressource clé
Reduced erosion, reduced loss of rainwater through runoff (increased in water use efficiency) and reduced fertility loss due to reduced slope angle and length How can they be sustained / enhanced? Maintain the quality of terrace construction.
Increased soil moisture How can they be sustained / enhanced? Construct/maintain a terrace lip to retain rainwater on the terrace
Increased crop production (before 1983 hunger and starvation in the area) How can they be sustained / enhanced? Combine with improved crop husbandry.
Easier field operations: the level terrace is easier to cultivate than the original hill slope.
Improvements of farmers’ living standard and decline in poverty stricken population.

6.8 Faiblesses/ inconvénients/ risques de la Technologie et moyens de les surmonter

Faiblesses/ inconvénients/ risques du point de vue du compilateur ou d'une autre personne ressource clé	Comment peuvent-ils être surmontés?
Terrace riser can be destroyed by storms – and, sometimes, rodent holes	Good and timely repair and maintenance: planting upper parts of the risers with grass, bushes or even trees help to stabilise the risers but can lead to competition with the crop for water.
High cost/input for construction and establishment	Given the high erodibility of the soil and the steep slopes there is no real alternatives to labour-intensive terracing.
High loss of soil moisture due to evaporation from the soil surface. Wind erosion due to tillage	Protect soil surface for example by conservation agriculture – comprising permanent cover, crop rotation, reduced tillage – could be supplementary agronomic and vegetative options.
Decrease in production in first year	Apply manure and fertilizer.

7.2 Références des publications disponibles

Titre, auteur, année, ISBN:

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

Titre, auteur, année, ISBN:

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

Titre, auteur, année, 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.

Titre, auteur, année, 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.

Titre, auteur, année, 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.

Titre, auteur, année, 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.

Titre, auteur, année, 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.