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Agroforestry

12 min read

What is agroforestry?

Agroforestry is a land-use system in which trees and shrubs are grown together with crops and/or livestock on the same land. The trees and crops interact, giving environmental and economic benefits.

SystemDescriptionExample
Alley croppingCrops grown between rows of treesMaize between Gliricidia rows
Boundary plantingTrees along field edgesTrees as fences or windbreaks
WoodlotsTrees planted for timber and fuelEucalyptus, pine
Home gardensMixed trees, crops and animals near the houseBanana, avocado, vegetables
SilvopastoralTrees with pasture and livestockFodder trees, shade for cattle
Improved fallowFast-growing legume trees planted to restore the soilSesbania, Tephrosia
TaungyaFood crops planted among young forest treesMaize among young pines
Alley cropping, a kind of agroforestryRows of fast-growing leguminous trees such as Gliricidia or Leucaena are planted with food crops growing in the alleys between them. The trees give shade, firewood and fodder, fix nitrogen, hold the soil and drop leaves that act as mulch.nitrogen-fixing tree rowsfood crops in the alleyleaf mulchshade + fodderroots hold the soil

Benefits and limits

BenefitsPossible problems
Leaf litter adds humus and nitrogen (legume trees)Trees may compete with crops for light, water and nutrients
Roots and cover prevent soil erosionSlow to give a return
Shade, windbreaks, fodder, fuelwood, timber, fruit and medicineNeeds knowledge and care
Extra income and a variety of foodPests may live in the trees
Carbon storage and habitat for wildlifeLand tenure may be unclear
Illustrative values: alley cropping with Gliricidia can raise maize yields.

Spacing and planning

The number of trees per hectare depends on the spacing: for example, rows of trees 4 m apart with trees 0.5 m apart in the row (alley cropping) give 5 000 trees per hectare. For woodlots, 3 × 3 m spacing gives about 1 100 trees per hectare.

The same formula as for crops.
Try itTrees per hectare

Choose the spacing of the trees.

Check yourself Alley cropping is growing
Check yourself Which tree adds nitrogen to the soil?
Check yourself A disadvantage of agroforestry can be

Key terms

Agroforestry
Growing trees together with crops or animals.
Windbreak
A row of trees that protects crops from the wind.
Woodlot
A plot of trees grown for wood.
Fodder
Feed for livestock.

Summary

  • Agroforestry combines trees with crops or livestock.
  • Systems include alley cropping, boundary planting, woodlots, home gardens and improved fallow.
  • It improves soil, gives wood and fodder and protects the land.
  • Trees per hectare = 10 000 ÷ (row spacing × tree spacing).
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