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close this bookResource Management for Upland Areas in Southeast Asia - An Information Kit (IIRR, 1995, 207 p.)
close this folder3. Soil and water conservation approaches
View the documentIntroduction to soil and water conservation approaches
View the documentBench terraces
View the documentComposting
View the documentContour tillage/planting
View the documentCover crops
View the documentCrop rotation
View the documentDiversion ditches
View the documentDrop structures
View the documentGrass strips
View the documentHedgerows
View the documentMinimum tilIage/zero tillage
View the documentMulching
View the documentRidge terraces
View the documentShifting cultivation
View the documentSoil barriers
View the documentSoil traps
View the documentWater harvesting

Bench terraces

Bench terraces are a soil and water conservation measure used on sloping land with relatively deep soils to retain water and control erosion. They are normally constructed by cutting and filling to produce a series of level steps or benches. This allows water to infiltrate slowly into the soil. Bench terraces are reinforced by retaining banks of soil or stone on the forward edges. This practice is typical for rice-based cropping systems.

In China, a modification of bench terraces includes an interval slope planted with perennials and grasses between individual terraces. This system is suitable where soil erosion is critical, rainfall is low and labor and farm manure are not typically available. Shrubs or herbs can also be grown on the edges of the terraces.


Typical bench terrace


Modified bench terrace with Interval slope (China)

Advantages

Effectively controls soil and water runoff and erosion.

Traps sediment in the drainage ditches built along the terrace.

Reduces slope length. Every 2-3 meters of slope length is levelled to terraces. The velocity of water running down the slope is greatly reduced.

Improves soil fertility over the long run.

Limitations

Initially disturbs the soil, reducing productivity in the first 2-3 years.
Needs intensive labor and investment for construction and maintenance.
Needs skills for proper construction.
Terraced fields with an interval slope consume much land.

Factors affecting adoption

Biophysical

Not suitable for shallow and slipping upland soils.
Not suitable for potato-growing since the terrace tends to become waterlogged.
Terraces with interval slopes can be used in regions with little rainfall.

Socioeconomic

Labor shortages and low incomes make bench terraces difficult for farmers to adopt in some areas.

Lack of secure land tenure serves as a disincentive to long-term construction measures, such as terraces.

In areas with poor soils, the terraces have a low return on investment.