No. 78 Thank you very much! and Inga edulis
By Tiiu Miller | Newsletter No. 78 January-February 2017

We made it!

Thank you very much to all who helped to make our raffle a success. We raised £1192, which gave a profit of £1147 after paying for printing and postage. Together with donations, both extra donations in response to the appeal and regular donations over that time interval, we reached and exceeded our target. Great result! Thank you!


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The money helped to cover the costs of the very long and difficult trip that Gaston Bityo, our Cameroon partner, made to see how the people he trained as Inga promoters at Kumba in February were getting on. He also went on to Mundemba and Fabe and gave a training session to another group who had been unable to come to the training at Kumba. We will report on that in another newsletter. Suffice it to say here that a good bit of work was progressing, and more is planned.Description: Macintosh HD:Users:tiiuimbimiller:Inga Project:Website_Newsletter:January-February 2017:WebJan-Feb2017:Webclass_nursery.jpg

Training session at Fabe, and Gaston Bityo inspecting Pastor Nsandah’s Inga nursery at Nguti. Pastor Nsandah was one of the trainees at Kumba in February.

In this, and the next couple of newsletters, there will be brief accounts of what we do, how and why, particularly for these of you who have subscribed recently, or to refresh your memory if you came across us a long time ago.

Though we are supporting research into the possible use of other trees, currently our work is based on the exceptional characteristics of Inga, with Inga edulis being the best species generally used.


Inga edulis (the species most commonly used for alley cropping)

The image I used to illustrate the funding tracker was copied off a photo of a real Inga seedling. It looks top heavy, and, as you can see from the photos below, as it grows the branches tend to spread out. This is one useful feature of this remarkable tree. For alley cropping the trees are planted in rows or hedges, fairly close together, with spaces, the alleys in between. As the trees mature the branches from the rows meet across the alleys, cutting off the light, and thus killing the weeds. A big bonus for any farmer.


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A young Inga seedling, and a somewhat older tree, showing how the branches tend to spread out.


Next the tree is pruned to let the light in so that the crops can be planted in the alley. It is a legume that has root nodules formed by nitrogen fixing bacteria. This means that the prunings fertilise the soil in the alleys. Lack of available nitrogen is a serious limiting factor for plant growth.


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Nitrogen fixing (making the nitrogen from the air available for plants to use) root nodules formed by beneficial bacteria. Other beneficial fungi in the roots take up phosphorus so it gets recycled and not washed away by the rain.


After the crops are harvested the Inga trees grow back. It’s a tough tree. The trees should not be pruned too low or they may die, but even then they can sometimes survive, as in the case of the one shown below that is regrowing after severe storm damage. The cycle of pruning, sowing, harvest, regrowth of the Inga trees and then back to pruning is repeated year on year.


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Inga tree regrowing after severe storm damage.


The healthy growth of the maize in the photo below shows that the Inga has fertilised the soil. We have done a few comparisons with sowing maize on a plot adjacent to the Inga plot, but without the Inga. The best Inga plot produced 15 times more than the comparison plot. The yield from the comparison plot was very poor, showing that the Inga can indeed fertilise degraded land.




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On the left healthy maize growing in an Inga alley. On the right is the comparison plot without the Inga, sown at the same time with the same seed. The maize in the comparison plot is only barely as high as the hen, whereas it is as high as the children at the back of the Inga plot.



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A mature Inga alley, and some of the harvest from an Inga alley.


There is a short animation at

that shows how the system works.



With best wishes and thank you for your continued interest in our work,