This page is for sharing practical lessons that we are learning as we go along, which are relevant to all aspects of Inga alley cropping, how to implement it and how best to promote the Inga system to the farmers.
The Inga trees seem to grow faster in Cameroon and Ecuador than in Honduras. This is an impression rather than accurate measurement. This could be due to Cameroon and Ecuador being closer to the equator. Fast growth can cause the Inga to overgrow a crop which is still growing, leading to no or reduced harvest. The remedy is of course to prune the Inga again while the crop is growing. Farmers need to be made aware of this. The system is very new to them and they don’t necessarily think of that themselves.
It seems too that rather than leave an interval of 6 weeks between pruning and sowing a shorter interval of maybe 4 weeks or even less may be appropriate. However, for the very first pruning this might not allow enough prunings to rot down. If there has been good leaf fall beforehand that might not matter.
Possibly wider alleys, say 5 or 6m rather than 4m, would also help.
The Inga have grown too fast and are badly shading the struggling maize.
We have had success with many different crops: maize, cassava, pineapples, cocoyams, beans, peppers, ground nuts, and more.
The farmers have a tendency to plant maize in the alleys while the Inga is still young and has not yet been pruned. It is therefore necessary to emphasise that they must not plant a tall crop that will shade the Inga.
When the farmers put their Inga into cocoa farms rather than for alley cropping, this will help their cocoa production a lot, and give Inga seeds for later planting of more Inga, hopefully in alley structure as well.
The Inga mulch is good at maintaining moisture so that crops can thrive even in some drought. But crops should nonetheless be sown when there is some rain. We have had crops fail because they were planted too late in the planting season. The Inga mulch cannot hold moisture when there is none to begin with.
What is best will depend on the exact conditions. The initial advice was to plant into polybags. These would be filled with forest soil that would contain the necessary micro-organisms (nitrogen fixing bacteria and mycorrhizal fungi that take up the phosphorus). If the farmer is supplied with Inga seedlings in bags (for example grown initially in bags by a project) these are more robust than seeds, which have to be kept moist and planted out within days. So if the farmer does not plant them out quickly they will still survive. Also they will survive some lack of water better than very young just germinated seeds.
The disadvantage is that the bags cost money and tend to be left lying around as litter.
Planting directly in the ground (bareroot method) has been found to be successful in some of the planting done in our Ecuador project, and the local project manager claims that these trees grew better than those first grown in bags and then planted out.
We have done some experimentation with planting bareroot in a nursery but do not at present have results to report.
Inga has also been successfully propagated by cuttings. This has the disadvantage that there will then be no genetic variability.
Comments from one of our Cameroon partners, Atanga Wilson.
‘You have now planted Inga seeds in three ways: polybags, bareroot and direct into the ground. Which method do you think is the best? Polybags and bareroots,.
This will depend on how far the nursery is to the farm where the Inga will be planted. It will also depend on the regularity of rain fall. But Inga seedlings raised with biodegradable poly bags will be the best option.
You say some of the bareroot seedlings died after they were transplanted. Why do you think they died?
Long distances walking on foot from the nursery to the farm. Transplanting when the sun is overhead or hot as from 1: 00pm. Did more of them die than when you grew them first in polybags? Yes, especially those planted in the afternoon and when rain does not fall 3 day after transplanting. But no difference with those from polybags planted in the morning and evening (5: 00pm) hours and rain falls.
How does planting the seeds directly into the ground compare with these other methods?
Seeds planted directly grow very slowly because there is no care on the farm as in the nursery and face more shock when there a dry spelt/absence of rain for a week or two.
I recommend biodegradable poly bags for Inga nurseries. If no biodegradable poly bags are available then go for bareroots Inga nurseries and treck for very short distances to plant the bareroot seedlings.
NB Established bareroot nursery near farm sites’
We have some results from Ecuador. Ecuador is right on the equator, so it is likely that for countries further away from the equator the Inga would not thrive as high as it would there.
We now have Inga plots at 800m altitude on the edge of La Bonita forest in Ecuador. We also planted Inga higher at 1800m and demonstrated conclusively that it will not grow at that height – the seeds germinated but hardly grew.
Add manure to the seed bags, or the holes in the ground for direct planting in the ground. To date we have no data as to whether this is worth doing.
Rock phosphate is recommended by Mike Hands, the original researcher. However we have had good results in both Cameroon and Ecuador without using it, and do not therefore recommend it, at least to begin with. Maybe it will be necessary in some very poor soils.
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