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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

Crop rotation

Considering its widespread adoption, crop rotation is arguably the most important crop management practice in Southeast Asia. Various crop species are grown in sequence, one after another, in the same part of the farm or field. These cropping patterns can vary from year to year; but they are designed to achieve a common result: better soil physical and nutrient composition.

Each crop places a different demand on the soil in which it is grown. Likewise, each crop leaves some amount of beneficial residue or performs some action on the physical structure of the soil. A good crop rotation takes into account each crop's characteristics-what it takes and gives back to the soil-so that the net effect is improved soil.

In agroforestry systems, the perennial crop component can be changed after a number of years. This would be considered one rotation. The agricultural crop component can follow a shorter rotation period, usually less than one year. Agroforestry requires a longer-term approach to rotations, involving a wider variety of crops, each with a unique production cycle.

A typical crop rotation is rice-mungbean-corn-cowpea. Since legume crops increase soil nitrogen, mungbean (Vigna sinensis) is planted after rice (Oryza sativa), to replenish some of the nitrogen and other nutrients taken by the rice. Likewise, cowpea (Vigna radiata), with its nitrogen-fixing ability and positive effects on soil, can be grown after corn (Zea mays), which places relatively high demands on the soil.


Peanut

Advantages

Very effective in improving soil fertility.
Reduces nutrient drain.
Helps sustain crop production.
Diversifies crop production.
Helps controls pests and diseases.

Limitations

May be difficult where input supplies are poor.
Less applicable for long-term crops.
May require a farmer to plant a crop which is not the highest priority.
Demands more skills of the farmers.

Factors affecting adoption

Biophysical

While nutrient supplements are still required, crop rotation lends itself to sustained crop production.
Crop rotation can be designed to work well in poor soil conditions.

Socioeconomic

Can produce increased income in the long run, but may yield lower income in the short run.
Can supply a varied diet.
Short-term tenure discourages conservation objectives.
Can have a high labor demand-a problem especially in areas with seasonal migrations.
Precludes intensive crop production in the offseason.