Inga alley cropping is a sustainable alternative  to  slash and burn farming. The Inga are legumes that fix nitrogen and recycle phosphorus. Inga trees are planted in rows with spaces (alleys) between them. Once grown, the trees cut off light in the alleys which suppresses weeds. The farmer can then prune the trees. Larger branches make firewood or are turned into biochar, while smaller branches and leaves are left to rot on the ground to form a fertile mulch. Crops are then planted. After harvest the trees regrow and the cycle is repeated.

Slash and burn farming is a form of shifting agriculture where the natural vegetation is cut down and burned to make way for crops. The land is fertile the first year or two, but then it becomes infertile as heavy rain washes the nutrients out of it. The farmer then has to clear a new plot of rainforest.

The Inga method keeps farm plots fertile, with high crop yields, long term. They do not need any chemicals – only Inga seeds – so the system is inexpensive, the produce is 100% organic and it is easy to increase plot sizes. The Inga is even capable of fertilizing degraded land, enabling farmers to cultivate previously over-used land near their homes instead of having to seek new plots farther away. They also benefit from preserving the forest.

By protecting the forest we can: 

• Save biodiversity (including sources of food and medicine)
• Keep the carbon in the rainforest, which keeps absorbing more
• Maintain rainfall
• Generate oxygen from the forests
• Reduce flooding and erosion
• Protect rivers and watersheds
• Preserve the homes of many indigenous people
• Absorb carbon from the Inga system itself

The closest comparable system is Forest Gardens. While Forest Gardens is a good system, in comparison Inga:

• Is less expensive
• Is simpler
• Requires fewer resources

The Inga system is easier to propagate, deploy at scale and spread from farmer to farmer.

According to recent research, slash and burn farming accounts for a quarter of rainforest loss globally. In Africa it may be as much as 90%.