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Book Reviews

Pigeon Pea and Chickpea Release Phosphates

Living Support Poles for Yams (Diascorea spp)

Toxicity and Food Security: A review of health effects of cyanide exposure from cassava and of ways to prevent these effects

Storing Cooked Eggs

Nutritive Value of Nuñas (Popping Beans)


Articles in this Issue


Pigeon Pea and Chickpea Release Phosphates

We all know that legumes such as these two plants add nitrogen to the soil. Now scientists at ICRISAT in India have shown that they make available more phosphates. They do not add phosphate to the soil, but rather break up phosphate compounds in such a manner that phosphate that was already present but unusable by plants is now available. If you work where phosphate is one of the most limiting nutrients (a common situation in tropical soils), you might want to work these crops into your rotation.

Echos from Our Network

Cheru Tessema in Ethiopia asked local farmers how they keep monkeys out of their fields

Neem disease in West Africa. While there are still many neem trees (particularly in plantations) that continue to suffer from decline, many other neems (in villages, along roadsides and in the Majjia Valley windbreaks) have leafed out and gone through a period of unusually heavy flowering. In some cases the same trees have flowered twice in the last several months

Book Reviews

INTRODUCING THE CAMEL, by Peter Grill. Lamar Witmer in Kenya sent us a copy of this unique book. He wrote, “I’ve read a number of books about camels. The one I am sending you is the one I believe to be the most useful as a single guide for development workers among pastoralists who herd camels. It emphasizes practical concerns rather than purely scientific ones. It was written from the perspective of eastern Africa, which may limit its usefulness in other regions.

TREES AND SHRUBS FOR THE SAHEL. Someone in our network in Mali (I lost track of who it was sorry!) brought this book to our attention. This beautiful 525 page book is still relatively compact (15x21 cm) for ease of carrying with you into the field.

A TOOL KIT FOR FOLKS INVOLVED IN AGROFORESTRY. (Reviewed by Scott Sherman).

Toxicity and Food Security: A review of health effects of cyanide exposure from cassava and of ways to prevent these effects

Martin L. Price

Dr. Rosling does not like the statement “cassava contains cyanide.” A food that contained pure hydrogen cyanide could be easily detoxified (it would be driven off as a gas by cooking). If any free cyanide is present in cassava, it can easily be driven off into the air by temperatures over 28°C (82°F )

The “cyanide” in cassava is actually a complex and very stable molecule called linamarin, one part of which is a cyanide molecule. If that part of the molecule is broken off it will become cyanide. Compounds such as this that produce cyanide when broken down are called “cyanogenic” compounds. Some cyanogenic compounds are broken down by boiling. For example, although chaya leaves contain a cyanogenic compound, the cyanide is driven off by boiling for 5 minutes.

Unfortunately the cyanogenic compound in cassava is largely unaffected by boiling. Boiling whole pieces of cassava does little to reduce the danger of cyanide poisoning.

Storing Cooked Eggs

Just because eggs can be stored for some time without refrigeration does not mean the same is true of cooked eggs. In its raw state, the egg has several antimicrobial defenses. The cuticle, or outside portion of the shell, protects the eggs from bacterial invasion as long as this layer remains intact. The shell membrane may be an even more resistant barrier for bacteria. Furthermore an enzyme called lysozyme in the shell membrane and in the egg white destroys many bacteria. Cooking not only inactivates the egg’s lysozyme, but also enlarges the shell’s pores. But the most important breakdown in defenses may occur when boiled eggs are cooled in water. The contraction of the egg during cooling creates an air pocket which produces a vacuum which can draw in bacteria present in the cooling water.

Grow Small Fruit Trees in Circles

A novel idea has been to grow some fruit trees, like bananas and coconuts, in circles about 3 meters in diameter.

Nutritive Value of Nuñas (Popping Beans)

Martin L. Price

Nuñas are varieties of common beans, Phaseolus vulgaris, which burst when toasted. In spite of the common name “popping beans,” they do not actually pop. Rather, when heated in hot oil or on a hot dry pan, they expand and split open. This is all the cooking they require. “The resulting product has a powdery texture with a taste between that of popcorn and roasted peanuts.” Most of our staff very much enjoyed the very few beans that we could spare for eating as a snack.

Nuñas are cultivated in the highlands of Ecuador and Bolivia between 2,000 and 3,000 meters. In regions where firewood is scarce, the benefit of these beans obviously extends much beyond their unique taste. Most beans must normally be boiled for a long time to be adequately softened. This time is even longer in the mountains where the boiling point of water is well below 100°C. Nuñas require only 34 minutes of cooking.

Another Use of Buckwheat: Eat the Leaves

 The newsletter HortIdeas quotes from an Indian journal that the leaves of this “broadleaved 'grain’ with remarkable soilbuilding abilities are edible. In fact, they are eaten regularly by people living in the higher ranges of the Himalayas. They are simply cooked with seasonings in boiling water for a short time. The leaves contain 4.5% protein on a fresh weight basis and are reasonably high in calcium and iron.”

Living Support Poles for Yams (Diascorea spp)

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.