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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

Cover crops

Cover crops are grown to protect the soil from erosion and to improve it through green manuring (the plowing-under of a green crop or other fresh organic materials). These are usually short-term crops (less than two years), planted in fields or under trees during fallow periods. Cover crops are also interplanted or relay-planted with grain crops such as maize, or planted once in a cropping cycle. Cover cropping is practiced in the Philippines and other Asian countries to suppress weeds under rubber and coconut plantations and to provide forage for animals. Cover crops can also be used in fallow systems to improve soil fertility quickly and shorten the fallow period.

Most of the plants used as cover and green manure belong to the legume family. Examples are:

Desmanthus virgatus
Phaseolus atropurpureus
Centrocema pubescens
Clitoria ternatea
(butterfly pea)
Sesbania rostrata
Vigna radiata (mungbean)
Pueraria phaseoloides (kudzu)
Cajanus cajan (pigeon pea)
Desmodium heterophylla
Tephrosia candida

Advantages

· Improves soil fertility and physical and chemical properties.

· Reduces soil erosion and water loss.

· Suppresses weeds.

· Reduces need for fertilizer and herbicides.

· Provides human food and animal forage.

· Increases soil organic matter.

· Helps retain moisture in the soil and prevent soil from drying.

· Some cover crops can provide good cash income through sale of products (e.g., pods, seeds).

Limitations

· May compete for soil moisture and nutrients with the perennial crops.
· Involves additional farm labor and inputs.
· May result in weed problems.
· May be alternate host for pests.
· Some cover crop species may contain chemicals which inhibit subsequent crop growth.
· Rats or snakes may hide in dense cover crop foliage.


Cover crops in long - term fallow system


Cover crops in long - term fallow system

Factors affecting adoption

Biophysical

Not applicable on steep slopes.

Contributes to improved soil fertility.

Some cover crops are prolific seeders and difficult to control, while other species do not seed well under some climatic conditions.

Socioeconomic

Reduces the need for herbicides and labor required for weed control.

May not appeal to farmers with short-term tenure.

Can require additional labor.

Cover crop generates lower short-term income.

Cover crops often do not yield a product which has tangible benefits (i.e., food, seed, etc.)

Many cover crop species are palatable to livestock. They can produce good fodder but be difficult to establish if livestock are allowed to graze.