After four days travelling in Laos, including two along the MeKhong upstream from LuangPaBang to Chiang Khong ,and seeing NO good farm land management, numerous landslides taking croplands down into the red streams and swidden farming the whole way along the MeKhong except for occasional forest patches, this very pertinent email arrived. The sender is bird-watcher Khun Iain, formerly a tree planter with Gum Hak Doi Suthep, now living in the Shetland Islands.
I have just been watching a documentary called “Up in Smoke” on the UK Channel 4 network – possibly available on-line. It tells the story of a British scientist, Mike Hands who has been working in Central America, mostly Honduras, for some years trying to reduce the negative effects of “slash & burn” cultivation. Apparently besides destroying the rain forests, slash& burn puts much more carbon into the atmosphere each year than all forms of carbon-emitting transport put together. He found that by planting a tree called Inga he could hold the nutrients in the soil.
The method of crop planting is called “alley cropping” as the crops (mostly maize & beans) are planted in “alleyways” through the Inga. Unlike traditional slash and burn where you get one good crop after the burn then the soil fertility drops off so you have to cut a new patch, with Inga the fertility remains pretty constant enabling multiple crops and the the subsistence farmers can remain in one place.
For whatever reason he has been unable to convince the world that this system works, though he has had considerable success with farmers in Honduras who once they saw the system in action were quick to adopt it as it provides them with sustainable crops, involves much less work than slash and burn every year and also enables them to stay put on one bit of land rather than moving on every few years. I understand that Inga species are all native to South & Central America and belong to the Mimosa family. Your mission, if you choose to accept it, is to find a native S. E. Asian tree that would do the same thing!
The above is a very short précis of a much more complicated story but with half of Borneo, Indonesia, Thailand & Lao going up in smoke every year this approach must be worth investigating.
Let me know when you’ve cracked it!
Well Iain, there have been attempts at cracking the problem here e.g. promising trials of Peltophorum dasyrrhachis, a native of these parts but to the traveller’s eye no implementation of alley cropping.
Perhaps some of our farming readers can bring us up-to-date?