This process is being used by farmers near the University of Philippines at Los Baños. Fast-growing nitrogen-fixing trees such as leucaena, gliricidia or calliandra are planted ahead of time to shade out grasses. Yams are planted near the base of the tree after weeds are controlled. When the tuber begins to form, the tree bark is removed about 40 cm from the ground. This causes leaves to drop, giving full sun, mulch, fertilizer and support for the vine and eventually provides firewood. One strong sucker is left from the new tree growth below the girdled area to produce another tree.
EDN reader Peter Afekoro in Nigeria writes that a lot of farmers have developed the habit of using the growing branches of the moringa tree as a source of stake material for yam vines. The interesting aspect to him is that when you cut the young tree for the stake, it sends up 6-10 new trunks for use next year. [It tends to be weak, fast rotting wood however].
We discovered quite by accident here at ECHO that yams love to grow right up living moringa trees. The light shade does not seem to harm them at all, nor do the vines seem to harm the moringa tree.
The April 1990 issue of Agroforestry Today reports that farmers in Kenya’s eastern highlands are using a local tree, Commiphora zimmermannii, (local names: mutunguka, mururi, kitungati) as stakes for both yam and passion fruit. It is drought tolerant, easily rooted from green stakes, slow growing with few lateral roots that might compete with crops, no large, dense canopy to shade crops, and it thrives under frequent pollarding. (Pollarding is cutting back severely to a certain height, then letting new branches form near the top). “Heavy vines would kill many trees, but Kenyan farmers claim that the mururi, once established, is permanent.” A picture shows a farmer with yams on living stakes that appear to be about head high that were planted 20 years ago. “Few species could survive under these dense and heavy vines.” It is also popular as living fences and is legally recognized as boundary markers because it is so permanent.
If any of our Kenyan readers can supply us with enough seed (if it makes seed) to make up 30 or so packets to offer to our network in other countries, send details including postage costs and any insights you may have about growing the tree. We would need to send you an import permit before you shipped the seed. We will announce availability of the seed in a future EDN if we are able to find seed.
ECHO Staff 1992. Living Support Poles for Yams (Diascorea spp). ECHO Development Notes no. 38