ECHO Technical Notes

TN #44 Methane Digester - 2001-01-01

When organic material decomposes under anaerobic conditions, it produces biogas which is a mixture of methane (CH4) and carbon dioxide (CO2) with small quantities of hydrogen, nitrogen, carbon monoxide and other compounds. Biogas can be used as a fuel source for cooking, heating, producing light or even fueling a generator. A methane digester is a device used to produce and capture this biogas. There are many designs for methane digesters ranging from large and complex to small and simple. This document will cover 2 main types of digesters: batch digesters and flow-thru digesters; and 2 main types of gas collectors: tube collectors and floating collectors.

Cite this article as:

Doerr, B. and N. Lemkuhl 2001. Methane Digester. ECHO Technical Note no. 44.

TN #43 BioSand Water Filter - 2001-01-01

Access to clean drinking water remains one of the greatest challenges in the world. The BioSand Filter is one method that can be used for purifying water at the household level. With this filter, contaminated water is filtered through a natural biological layer and then layers of sand, pebbles and stones. The BioSand Filter can be made using local materials and is a low-cost system that removes suspended sediments and other impurities from water in order to make it safer for human consumption. 

What’s Inside:

• Household Water Treatment
• Filter Details Materials for Construction Filter
• Construction Filter Assembly
• Filter Use Filter
• Maintenance Additional Resources 

Cite this article as:

Doerr, B. and N. Lemkuhl 2001. Biosand Water Filter. ECHO Technical Note no. 43.

TN #42 Haybaler - 2001-01-01

This simple device provides a method of manually producing bales of hay. Small-scale farmers may be interested in this technology because hay is both easier to store and easier to transport when it has been baled. Also, baled hay retains a higher nutrient content than hay that has been cut and left exposed to the sun.

Cite this article as:

Dahlman, J. and C. Forst 2001. Haybaler. ECHO Technical Note no. 42.

TN #41 Solar Dehydrator - 2001-01-01

Often the biggest challenge faced by a tropical farmer is not in the production of a crop but rather in the preservation of the crop. Farmers may want to preserve a crop for future consumption or for sale at a time when the market will offer a higher price.

Using a solar dehydrator is a simple, cost-effective way to preserve a variety of different crops. Dehydrating removes the moisture from food so that bacteria, yeast and mold cannot grow and spoil it. 

Cite this article as:

Dahlman, J. and C. Forst 2001. Solar Dehydrator. ECHO Technical Note no. 41.

TN #40 Sawdust Cookstove - 2001-01-01

There are many variations of sawdust cookstoves that have been used for many years both in North America and around the world. This sawdust cookstove model provides a low-cost, low-input method for producing a high intensity flame that will burn for up to five hours. The flame burns fairly clean with little smoke. This stove brings one gallon of water to a boil in approximately 12 to 15 minutes and maintains an intense temperature for two to five hours, depending on the fuel used and the compression of the fuel (fine, highly compressed sawdust burns longer than coarse or loose material). In addition to sawdust, fibrous plant waste such as rice hulls, chaff, coffee bean hulls and straw can be used as fuel. A mix of sawdust and coarser material works well.

Cite this article as:

Dahlman, J. and C. Forst 2001. Sawdust Cookstove. ECHO Technical Note no. 40.

TN #39 Introducing New Seeds Overseas - 2000-01-21

ECHO is frequently asked, by groups or individuals from North America, to suggest vegetable seeds to take with them on short trips overseas. Often the group is a “work team” that is being sent by a church. Someone with the group they are going to visit has asked them to bring vegetable seeds. Or perhaps the group has just decided that it would be a nice thing to do.

What's Inside:

• Gardening Differs in the Tropics
• Questions to Consider When Selecting Seeds
• Recommendations for Selecting Seeds for Use Overseas
• Pitfalls to Avoid and Some Positive Suggestions
• Considerations Before Sending Free Seeds
• Seed Sources

Cite this article as:

Price, M.L. 2000. Introducing New Seeds Overseas. ECHO Technical Note no. 39.

TN #38 Cashew - 1999-01-01

The cashew, Anacardium occidentale, is a resilient and fast-growing evergreen tree that can grow to a height of 20 m (60 ft). It belongs to the family Anacardiaceae, which also contains poison ivy and the mango. Native to arid northeastern Brazil, the cashew was taken around the world by the Portuguese and Spanish who planted the trees in their colonies. The English name "cashew" is derived from the Portuguese "cajú" which came from the Tupi Indian "acaju" (Rosengarten, 1984). In Spanish it is known as "marañón" or "anacardo."

Cashew is an important nut crop that provides food, employment and hard currency to many in developing nations. Of all nuts, cashew is second only to the almond in commercial importance (Rosengarten, 1984). India, Mozambique, and Tanzania are the three biggest exporters of cashew nuts today. Although there are large commercial plantings of cashew, wild trees or those owned by small farmers account for 97% of cashew production (Rosengarten, 1984).

The plant produces not only the well-known nut, but also a pseudofruit known as the cashew "apple" and cashew nut shell liquid (CNSL) which is used for industrial and medicinal purposes.

The cashew tree has other uses as well. It is used for reforestation, in preventing desertification and as a roadside buffer tree. Cashew was planted in India in order to prevent erosion on the coast (Morton, 1960). The wood from the tree is used for carpentry, firewood, and charcoal. The tree exudes a gum called cashawa that can be used in varnishes or in place of gum arabic. Cashew bark is about 9% tannin, which is used in tanning leather.

Cite this article as:

Davis, K. 1999. Cashew. ECHO Technical Note no. 38.

TN #37 Egusi Recipes - 1998-11-01

In West Africa, the name Egusi is applied to members of the gourd family having seeds of high oil content. Egusi Melon plants closely resemble watermelon plants; both have a non climbing creeping habit and deeply cut lobed leaves. The pulp of the watermelon fruit, however, is sweet and edible while the Egusi Melon has bitter and inedible fruit pulp. Egusi Melon seeds are larger than watermelon seeds, and they are light colored. Egusi Melon is cultivated in portions of West Africa, especially in Western Nigeria, for the food in the seed and as a crop interplanted with maize, cassava, or other crops.

Cite article as:

Welch, R. and K. Smith 1998. Egusi Recipes. ECHO Technical Note no. 37.

TN #36 Jicama - 1998-10-01

Jicama (Pachyrhizus erosus) of the fabaceae or leguminosae family is a short-lived perennial, often grown as an annual leguminous climbing vine, which during short days will flower, produce long, inedible pods, and develop tuberous roots. These are few in number per plant, usually spherical, but often lobed, and weighing several kilos per plant. The flesh of the root is white and crisp, even after cooking, and is covered with a tan skin or cortex, which is easily removed by peeling.

Jicama, (pronounced, HEE-kah-mah) also known as yam bean, originates in Meso-America and is naturalized in agricultural areas throughout the tropics. It is excellent for commercialization where markets exist, a useful home-grown crop for varying the diet, and a novelty vegetable for special uses due to its taste and crisp texture.

Cite this article as:

Price, M.L. 1998. Jicama. ECHO Technical Note no. 36.

TN #35 Quail: An Egg & Meat Production System - 1998-09-01

Many families in the tropics must assume a major role in production of their own foodstuffs. Incomes are so low that purchase of food competes with purchase of necessary items that cannot be hand-made. Most governments in the tropics do not have the resources to guarantee even minimum food to all of their citizens. Families in rural and urban situations often live in a minimum of space without soil that can be cultivated, or even a backyard in which a few animal cages can be placed. Such persons sorely need small scale systems that are in harmony with resources available.

Unfortunately, not enough study has been given to small-scale production systems. The small animals typically encountered on almost every small farm, chickens, ducks, geese, and rabbits, are still too large for many households. A small animal for a minimum sized system should produce food in units that can be eaten at one meal so that refrigeration is not necessary. Furthermore, such systems should use resources available to most families, including feeds that can be grown or purchased, cages that are home made, and systems of sanitation that
protect the health of the animals and the residents of the household. The development of such systems has not attracted serious investigators.

The system described here, based on the Japanese quail, Coturnix japonica, is based on sound published information on this species and its requirements, and on three years of experimentation with quail at the household level. All apparatuses described were built and used, and actual costs and yields are reported.

Cite this article as:

Martin, F.W., A. Martin-Davis, and A. Maffioli 1998. Quail: An Egg & Meat Production System. ECHO Technical Note no. 35.