F17 Alley cropping

  • A common method of agroforestry is called ‘alley cropping’. Closely planted lines of suitable trees are spaced about five metres apart – usually by direct seeding or transplanting from tree nurseries. The lines are placed across a slope, within areas where crops or vegetables are grown.
  • The lines of trees are planted closely together so that they grow to form a hedge. If possible, it is a good idea to mix several different species to form a hedge. Once the trees reach 1–2 metres high they are cut right back to just 20–30cm high. The leaves can either be left on the ground as a mulch to rot down and add nutrients to the soil, or alternatively they can be used to provide good animal fodder. The remaining stumps quickly regrow and the cutting back can be repeated for many years.

Discussion 

  • Only certain trees will tolerate this system of cutting back. The most useful are trees belonging to the legume family, since their roots also add plant nutrients to the soil. These include leuceana, calliandra, prosopis, acacia, sesbania and moringa. Do participants have any experience with any of these? Are seeds available?
  • Discuss how the lines can be planted along the contour on sloping land. If possible, visit a nearby farm which uses contour planting or hedges to prevent erosion.
  • How does alley cropping improve the soil and control erosion? Try to bring out in the discussion the facts that repeated mulching of the soil improves soil fertility and the ability of the soil to hold water. The lines of trees and their roots protect the soil from erosion. Legume trees also add nutrients to the soil.
  • Discuss what kind of crops could be grown with alley cropping.
  • What kind of areas would benefit most from introducing alley cropping?