Skip to main content
  • Weighing Pruned Inga Leaves

    Measuring and tracking results for research

  • Crop Fertilisation

    Dr Valle calculating the amount of nitrogen produced by one Inga tree in Ecuador

How To and the Science

General Considerations

Inga alley cropping is a tried and tested agroforestry technique designed to replace slash and burn farming  in tropical rainforest areas. It can maintain soil fertility long term and even refertilise badly degraded land. It is cheap to implement and once the farmers have seen it in action it is accepted well by them. However it is not a quick fix, as it takes between a 18 months and three years to establish an Inga plot.

Advice for Farmers

Inga alley cropping is suitable for tropical areas with good rainfall. Inga edulis is the most widely used species. It can grow on degraded, acidic soils and refertilises them. 

Lessons Learned

We share the feedback we get from the farmers and our overseas partners. You will find practical tips on Inga alley cropping that we have learned in this section. If you are engaged in doing Inga alley cropping we would love you to share any tips or experiences that you have that we can add to this section.

The Science

Inga alley cropping is based on substantial research and field trials. Inga trees are legumes. Legumes have nitrogen fixing bacteria in their roots in the white nodules. They also have mycorrhizae (friendly fungi) in their roots which recycle phosphorus and, we believe, other minerals as well. Loss of phosphorus from the soil was found to be an important reason why slash and burn plots lost their fertility so quickly. Several tree species, particularly several from the genus Inga, have been tried and the edulis and oerstediana varieties performed best in the demanding conditions of alley cropping with annual pruning.

Characteristics of Inga Edulis

  • It grows fast enough to be pruned annually
  • It withstands the annual pruning well
  • Its canopies close tightly over the alleys, shutting out the light and killing the weeds
  • The leaves are large and tough so that they cover and protect the ground
  • It can grow on the acid soils typical of rainforest areas
  • It is not poisonous

Resources to Download

  • Step by Step guide on how to do Inga alley cropping
  • An 8-page dissertation that is both a manual and source of further information
  • A two-sided A4 summary of the process in pictures, designed to be laminated and given to farmers
  • More leaflets and posters
Last updated: April 15, 2023