Participatory Experiments with Green Manure

Backgrounder

Have you heard…? From Guatemala The Boca Costa of Sololá, Guatemala is located at the base of the Santo Tomas volcano. The main crops in the region are coffee and bananas (800 to 1400 metres), corn, and beans. The corn growing land is sloping, and soil erosion is a major problem.

Maize yields in the area are low due to poor soil fertility. Farm plots are far from the highway, so the use of chemical fertilizer is not practical or cost effective. However, it is possible to plant green manure crops with corn to protect the soil from erosion, and to add nitrogen and organic matter to the soil to increase soil fertility and maize production.

ADERSO is a non profit organization in Guatemala which is doing green manure trials in this region with farmers’ participation. ADERSO works with farmers’ groups who choose two to three members of their group to be Local Agricultural Technicians. These technicians receive training courses at ADERSO and return to their communities to share their knowledge with the groups of farmers. In this way many people can be trained with few staff.

In 1992, groups of farmers from ten communities seeded trials of five kinds of green manures to determine which types grow well in the region. They planted velvet bean(Mucuna pruriens), alfalfa (Medicago sativa), kudzu (Pueraria phaseoloides), jack bean (Canavalia ensiformis) and sunnhemp (Crotalaria juncea). They took information about germination dates, growth rate, soil cover, nitrogen contribution, and the amount of vegetation produced. The best results were reached with sunnhemp, velvet bean, and jack bean, which established themselves well, grew quickly, and gave better soil cover than other crops.

From Costa Rica
Living fences in Costa Rica Using live trees or shrubs can be a cheap and effective way of keeping livestock within bounds. There are great possibilities for extending this practice where wood for posts is scarce and alternative materials are costly. Dr. Gerardo Budowski, working in Costa Rica, has made a study of live fencing and encourages farmers to plant trees for this purpose.

One way of making a living fence is to grow trees in lines and then fix barbed wire to them. The trees or shrubs can be grown so close together that they form an obstacle to cattle. This is how farmers in Costa Rica and other countries do it.

Living fences are very popular in Costa Rica and there are thousands of kilometres of them all over the country. The fences are easy to propagate. Two year old branches can be cut and sold to other farmers to plant. The living fences can also be used as fuelwood or for livestock fodder. Some bear fruit and others are medicinal plants. Dr. Budowski has identified 98 different species of fence trees and shrubs in Costa Rica. There is a fence for every purpose!

The living fences can be grown in most of the ecological zones in Costa Rica, except the highest one, where there are frosts. In the lowlands there are 20 or 30 different species which are being used and can be easily grown from large stakes.

The most commonly used species is Gliricidia. But Dr. Budowski’s favourite species for fencing is the genus Yucca. It is attractive and ornamental and it produces an edible flower every year, which can be sold. Yucca can also be planted in areas where there are landslides, because its roots bind the soil. Yucca is easily propagated, it is ornamental and prevents soil erosion. What more can you ask from a tree?

From Vietnam
“VAC” yard horticulture in Vietnam Farmers in Vietnam are increasing the productivity and sustainability of their backyard farms with help from the Vietnamese Gardeners’ Association. The Association is promoting the “VAC” system a method of mixed cropping that nourishes the soil and provides cash crops. In Vietnamese VAC stands for garden pond livestock pen. VAC is sponsored by UNICEF and promotes integrated vegetable, pig, and fish farming.

For example, a farmer in Xuan Phuong, outside Hanoi, is growing vegetables in his 720 square metre front yard to sell in Hanoi. He grows grapefruit, oranges, bananas, papayas, sapodilla, mint, squash, onions, amaranth, protein rich sauropus, and sweet potatoes. The plants grow at different levels and heights, providing shelter, shade, and nutrients for each other. The leaves of some plants are fed to pigs while other parts, such as sweet potato roots, are for human consumption. The yard is fertilized with pig manure and human waste.

The yard farm includes a small fishpond that has about 1500 fish. Species are carefully chosen to live well together. A kind of fish called tench feed near the top of the pond, carp in the middle, and tilapia at the bottom. The carp feed on the waste of the fish species living above. The pond is covered with water hyacinth that provides oxygen for the fish, protects them from the sun, and is fed to the pigs.

The yard also has a pigsty with a sow that produces up to 20 piglets a year. Yard greens and fish laced meal are served to the sow.

In 1992 the farmer made about US $450 from his yard. (The average Vietnamese annual income is $240). UNICEF estimates incomes of VAC farmers to be from three to 10 times higher than rice farmers. VAC gardens are also established by schools, churches, orphanages, old age centres and factories in Vietnam, to provide free or subsidized nutritious food.

The Gardeners’ Association has a corps of extension workers who are experts in the various farming systems. They provide regular advice to the VAC farmers.