General considerations regarding the practical application of Inga alley cropping
Where is it appropriate to use this technology?
Inga alley cropping was developed as an effective, sustainable alternative to slash and burn agriculture in the rainforests and former rainforest lands of Central and South America. Here the soils are frequently degraded and acid. It can also be used anywhere else where the Inga is native where the conditions are suitable for it to be grown. Not all the Inga species are suitable. Caution needs to be exercised in parts of the world where the Inga tree is not native.
It takes about two years to get Inga alleys established. However, the yield can be as much as four times higher than without the Inga, while the costs are minimal. And of course the same plot can be used over and over. We know of plots that are now over 10 years old and still providing as much yield as at the start.
How well has it been tried and tested?
There have been over two decades of meticulous research followed by field trials. The farmers who have taken it up have been able to stay on the same plot for many years and are very happy with it. At the end of field trials the plots had lasted six years with just one initial application of rock phosphate, but they have continued since. Even if, as is likely, some further rock phosphate is eventually needed, it is expected that this would ensure a further long fertile period and be very affordable for the farmers.
Do the farmers like it?
Yes, very much. The best proof of that is that when they have tried it on a small scale they want to expand their Inga plantings. But to convince them to try it in the first place they usually need to see it in operation. However, after a field worker from Guatemala had visited the Inga demo facility at CURLA and described and illustrated his visit with photographs of the Inga alleys he reported that over 5,000 families in the Maya heartland wished to try it. Nonetheless seeing demo farms is the best way.
Victor Coronado, one of the first Honduran farmers to try Inga alley cropping, Now demonstrating it to other farmers. Photo by Antony Melville 2007.
Moreover it is not a quick fix. From sowing the Inga seed to pruning and sowing the first crop takes generally two years, and if the soil or climatic conditions are very poor it can be three years, though in very favourable conditions less than two years may suffice. During that time the farmers are likely to need some support, both in the form of reassurance that it will work, technical advice, and maybe financial help such as some form of micro credit until they get the benefits of the first crop. They will also need seed and bags to grow the seed in, and fencing to protect the field, and probably rock phosphate to start off the system. Possibly the farmer would only put a small amount of his land under Inga to begin with and expand later.
The system has appealed particularly to farmers who have had to farm in the most difficult conditions, like on acid soil or on steep slopes. Inga alley cropping has been effective in preventing or reducing soil erosion on hillsides, even in very adverse weather conditions. This is clearly of great benefit to such marginalised farmers. It has also been very effective in reclaiming previously very degraded and useless land.
What does it cost the farmer in both time and money?
They need seed and bags to grow the seed in, and fencing to protect the field, and rock phosphate to start off the system and tools for planting and pruning.
Initially getting the system under way takes a good bit of hard work, but once the Inga is well established the farmer saves time
In the first year to establish the system the farmer has to preslash the site to keep down the weeds, then he has to plant the Inga, and then to slash the weeds again round the young trees till they are fully established, keeping an area of about a metre across clear round the base of each tree. This might come to over 100 man-days for a hectare. However most farmers would want to start much smaller than that, for example with a tenth of a hectare, and this would make the work quite manageable. More land could then be put under Inga alley cropping in subsequent years.
However from the second year on the alley cropping system requires very much less work than slash and burn, about only half the man hours as there is very little weeding to be done. Moreover for slash and burn there is often additional time, which can be as much as 2 or 3 hours a day, in walking to the latest cleared plot. As the alley produces for many years the farmer saves a considerable amount of time in the long run.
Amilcar's plot with well-grown Inga, La Hidaka, Honduras. Photo by Antony Melville 2007.
The only input that the system has needed is a bit of rock phosphate at the start. One application has lasted for six years in the field trials, and appears to be lasting much longer, as the Inga recycles what the crops do not use. Eventually other inputs may come to be needed, but again one would expect that these would be recycled and so used more economically in the Inga system than in many others.
One problem with adopting this system is that there is a delay of usually about two years before the Inga plot becomes productive. It may however be possible to plant beans sooner if the soil and climate are favourable. Also in addition to the good crops obtained later with the Inga system it produces firewood, which has been much valued by the farmers.
The trees are pruned before they flower. So if it is intended to produce Inga seed, for example to increase the area planted as Inga alleys later, or to supply neighbouring farmers with seed, a tree needs to be left unpruned, maybe at the end of a row, to flower and make seeds. Funders might stipulate that in return for seed, etc. the farmer grows one such tree to supply the neighbours with seeds later when they have seen how well the system works.
Inga seeds in a bucket of water. Photo by Antony Melville 2007.
For references, further reading and more detailed discussion see the next section Advice for Farmers