The lablab bean as green manure
The Lablab Bean (Dolichos lablab or Lablab purpureus) is a legume very similar in appearance to the velvet bean, but even faster growing where soils are fairly fertile. It has not been as valuable to us because of its need for somewhat more fertile soils and occasional insect problems, but may well be important to us later on when the other green manures have raised fertility sufficiently. The lablab bean is almost as drought-resistant as the jack bean, is very shade- tolerant, and is among the most palatable of legumes for animals (definitely preferred over velvet bean or jack bean). Lablab beans grow well from sea level up to about 1500 meters. They require well-drained soils. Lablab beans start flowering after 3 months and continue most of the first year, producing seed as well as remaining green. If soils are deep enough and other conditions permit, it will grow right through the dry season. I have seen plants that survived 3 years in droughty areas of the central plateau of Haiti. [Ed: in the sandy soils at ECHO lablab beans get nematodes so badly that it is difficult to keep them alive an entire year]. It nodulates profusely, producing mostly white nodules. Whereas the velvet bean growth is reduced if it has nothing to climb, plants in thick stands of lablab beans will begin to climb up each other. Another difference from the velvet or jack bean is that the lablab bean can be cut off nearly at ground level and will grow again, although with somewhat less vigor. Lablab beans are traditionally planted toward the end of the agricultural cycle in come villages in Honduras to provide dry-season pasture for animals. It is also edible, and in some places, such as Haiti and West Africa, is widely appreciated as a regular food. Young pods or immature beans can be eaten green (beans taste similar to a sweet pea - a white seeded variety is best for this). Dry lablab beans can be substituted for dry beans in most recipes. Where it grows well, the lablab bean has produced a phenomenal 11 kg per square meter (110 T/Ha) of above ground organic matter (wet weight). Though we have had problems with insect attacks, its growth is so vigorous that it still usually grows as fast as the velvet bean. Because animals prefer it to almost anything else, lablab beans cannot be grown where animals run free. In pure stands, lablab beans should be planted about 10/square meter. We have not found a good system yet for planting in corn fields because of its rapid growth, but it should be possible with heavy pruning (which it withstands well). The lablab bean requires either a recently cultivated or a sandy soil. Continuing research needs. If you have been experimenting with green manures, please send me whatever information you have put together [Ed: Please send a copy to ECHO too]. I think the most important subjects we need to learn more about are:
• (1) What legumes will work above 1,800 meters?
• (2) What additional plants will work at any elevation?
• (3) What green manures will work best under wet tropical conditions?
• (4) In what ways must these recommendations be modified for areasoutside of the caribbean basin area from which they have come?
Martin speaking now ... Thanks a million Rolland. ECHO will send a small packet of any seed mentioned in this article. If you want to buy larger quantities we will try to find a source. We also have the "90" day " velvet bean that was grown in the southeastern part of the USA 50 years ago. At the time of the last corn cultivation farmers would plant this velvet bean. Both corn and beans were left in the field. Cattle were allowed to feed in the fields a couple of hours each day in the fall and winter, reportedly getting very fat. This variety is not sensitive to day length so produces 3 months after planting. The tropical kind only produces when days are short (flowering starts in November at ECHO). The 90 day kind has some of the itch-producing hairs Rolland refers to, but not nearly as many as I have seen on the wild "pica-pica" in Honduras.
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