Monday, March 25, 2019

Inga Alley Cropping

I first heard about Inga Alley Cropping in 19th Organic World Congress (OWC) held in New Delhi in November 2017. There Mike Hands was honored with the 3rd Organic Farming Innovation Award (OFIA) for the Inga Alley Cropping system he had developed. The OWC highlighted Inga alley cropping as an innovative, real-world solution to promote sustainable agricultural practices and end slash and burn. I didn't pay much attention to it at that time, recently while reading some article saw some reference about this and read more about it.


Slash and burn is a farming method where the families cut down and burn patches of forest and do farming. Since the fertility is high initially they get good yields and 2nd year it reduces and by 3rd year it normally fails and families leaves this farming area and move to the next area. Hence Slash and burn is a big threat with increasing deforestation and pollution.

Inga Alley cropping is a sustainable farming system, based on nitrogen fixing tree Inga and this is a solution to slash and burn. Inga Alley cropping maintains fertility of soil year after year, there by slash and burn becomes unnecessary.

In this system of deep mulching using pruned green leaves from the trees which are contour-planted in hedgerows. It is capable of achieving food-security in basic-grains for the family, upon a permanent plot which can be located near their dwelling. The system produces firewood for the kitchen and virtually eliminates the need for weed-control.

Weed-control is achieved, firstly, by shading as the growing trees develop a dense canopy; and secondly, by smothering under the deep, tough mulch following the first pruning of the trees.  Once the crop has grown (3 months for maize and beans), the trees are left to reform their canopy until the whole process is repeated the following year.

The trees are pruned to chest height, the branches are stripped of foliage for the mulch; the finer branches are placed on the upslope side of the trees to help prevent soil movement, and the larger stems and branches are removed as a favourite domestic firewood. This tackles another important cause of deforestation.

Plant Inga trees in rows. Trees should be planted 1.5ft apart (18 inches) along the row, and rows should be 10ft apart. The rows should be oriented in east-west direction, if possible so that crops gets more sunlight. We can grow corn, beans, pepper, squash and other crops while the Inga trees are growing. When the Inga is around 12-15ft high (which takes 2-3 years) and its canopy is shading the whole field, cut the tree trunk at around 5ft from the ground. This releases the nitrogen accumulated in the tree’s roots into the soil, making it available for crops.

It takes only two to three years to establish an Inga alley plantation, and thereafter it functions year after year. That is acceptable.

Is this applicable in Kerala climate? Not very sure, we don't have Inga tree here, so possible leguminous trees are Subabul and Glyrecedia. Also there are reports that the root competition may be there between crops and hedgerow trees and width is an important factor considering this. I am planning to try this in one area where I am planting turmeric, worst case, after a period all these trees can be cut and mulched.



A friend called Suresh wrote to Mike Hands asking his suggestions as replacement for inga trees and here is his response.

"I woud have suggested Pongamia spp. as worth a trial, but neither Gliricidia nor Sesbania.  The reason is that they have small leaves that do not persist as mulch.  One of the characters if Inga is its tough foliage which protects the soil surface layers and suppresses weed germination.  

Pithecellobium spp. might work, but you would need a species with as big and tough a foliage as possible; it is botanically related to Inga.

Another genus which looks more promising and which is also closely related to Inga is Archidendron. There are many species across SE Asia and probably N. India.  I have seen it in Borneo and it looked very like some of the Inga spp. of which I have experience.  I strongly recommend this genus.

Another promising-looking species, widely used and coppiced as shade in Malaysia is Pterocarpus indica.  I have no experience of managing any of these"

I wrote an article about Inga alley cropping in a Kerala magazine called 'Ore bhoomi Ore jeevan'.


AndriusMan said...

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Unknown said...

I guess Sesbania grandiflora can be used:

Nandakumar said...

Not sure if Sesbania Grandiflora can be used, it is leguminous, but leaves are small and hence may not provide enough shade. Mike Hands had suggested to Pongamia tree, I am also trying if Asoka (Saraca Asoca) tree can be used.