Alley cropping is the growing of crops in the spaces between rows of trees. The spaces are the alleys. Inga alley cropping is the growing of crops in the spaces between rows of Inga trees.
For Inga alley cropping the trees are planted in rows (hedges) close together, with a gap, the alley, of say 4m between the rows.
When the trees have grown, usually in about two years, the canopies close over the alley and cut off the light and so smother the weeds.
The trees are then carefully pruned. The larger branches are used for firewood. The smaller branches and leaves are left on the ground in the alleys. These rot down into a good mulch (compost). If any weeds haven't been killed off by lack of light the mulch smothers them.
The farmer then pokes holes into the mulch and plants his crops into the holes.
The crops grow, fed by the mulch. The crops feed on the lower layers while the latest prunings form a protective layer over the soil and roots, shielding them from both the hot sun and heavy rain. This makes it possible for the roots of both the crops and the trees to stay to a considerable extent in the top layer of soil and the mulch, thus benefiting from the food in the mulch, and escaping soil pests and toxic minerals lower down. Pruning the Inga also makes its roots die back, thus reducing competition with the crops.
After the crops are harvested the Inga regrows and the cycle of pruning, sowing and harvest is repeated year after year.
This system increases yields and maintains the plot’s fertility long term, thus eliminating the need for the continual burning of the rainforest to get new fertile plots (slash and burn or shifting cultivation).
Rainforest Saver is at present supporting Inga projects in Honduras, Cameroon and Ecuador.
The Inga tree is native to many parts of Central and South America, but has been found to grow well in other parts of the world in the tropical rainforest belt. It makes a good shade tree for coffee and cocoa and has therefore been taken to many tropical countries.