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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

Shifting cultivation

This form of low-input agriculture and fallow management is common in Southeast Asia, particularly in rice, taro and cassava-based systems. It is also commonly referred to as swidden cultivation. If managed properly, it can be considered a sustainable practice, particularly in sparsely populated areas. In this system, the underbrush is cut, then most of the trees are felled. Certain tree species are left to stand and branches are pruned. In most places, underbrush is burned; but in parts of Papua New Guinea, no-burn practices are used. The branches and leaves are slashed and may be laid along the contour. Food crops are then planted using minimum tillage practices, such as dibble or digging sticks.


Slah and no burn


Slah and burn

Advantages

Slowly releases nutrients from the forest biomass to the soil (no-burn practice in Papua New Guinea).

Helps control weeds in the first three months, enabling crops to grow quickly (burn and no burn).

Retains soil moisture.

Easy method of clearing rainforest for permanent agriculture.

Minimizes direct impact of raindrops on soil surface (no burn).

Suitable for root crops and banana-based cropping systems.

Limitations

· Increases soil and nutrient loss.
· Soil nitrogen is lost by burning.
· Only simple land preparation (i.e., minimum or zero tillage) is possible.

Factors affecting adoption

Biophysical

Optimal planting density cannot be obtained on sloping land due to difficulty of planting.

Socioeconomic

· High labor input for clearing, especially under tropical forest conditions.

· Not suitable for fallow under 10 years due to existence of undesirable weedy species. (Papua New Guinea)

· Suitable only in areas with low population density.

· Many farmers believe that burning improves soil fertility. (Thailand)