Cover crops in Central America farmers show other farmers

Velvetbeans are aggressive annual vining legumes of the genus Mucuna. They originated in Asia and were introduced into Florida via the Caribbean in the 1870s for use as a cover crop in citrus groves. [See Buckles (1993, 1994) for more details on the rise and fall of Mucuna in the USA and Central America.] From 1900 to 1920 nearly 1500000 ha were planted with Mucuna spp. as green manure and animal feed in the southern USA. Numerous studies and extension bulletins were also completed on velvetbean in this period. By the 1940s velvetbean had disappeared in the southern USA due to the availability of cheap nitrogen fertilizers and the spread of soybean.

In the 1920s banana companies introduced velvetbean into Central America. They promoted its use in association with maize that was cultivated by banana workers on company lands. After maize harvest, mules used for banana transport grazed these fields.

When mules were replaced with tractors, the use of velvetbean declined on banana plantations, but spread to peasant fields. From the late 1930s onwards, the use of velvetbean for weed control and as a green manure has spread among communities of Guatemala, Belize, southern Mexico, and Honduras. In Atlantida, Honduras, from the 1970s to the early 1990s the number of maize producers using velvetbean increased from 10% to over 60%, largely based on farmer-to-farmer communication (Buckles, 1994). The different regions where velvetbean is used vary greatly in length of dry season and rainfall, factors that farmers have taken into account when adapting their systems for velvetbean use (CIDICCO, 1995).

Many nongovernmental development organizations (NGOs) throughout Central America over the past 10 years have begun to promote the use of leguminous annual cover crops with small farmers. Velvetbean and other cover crops are viewed not only as valuable for improving soil fertility and reducing weed control costs, but also as a way to motivate farmers to experiment with solutions to their problems with their own resources (Bunch, 1982). Farmers who have learned to manage velvetbean through experiments on their own farms play a key role in the farmer-to-farmer approach. These farmers, who are known as promoters, often begin by asking a group of farmers why they think their yields have declined. Promoters speak of similar problems in their home region and describe the use ofleguminous cover crops. The group may visit other farmers already working with cover crops. Promoters offer small amounts of seed for multiplication and testing. As farmers observe results and harvest seed, they encourage other farmers to try cover crops. Regional and national farmers' meetings are often organized to promote the exchange of results (e.g., Buckles & Arteaga, 1993; Lopez, 1993).

Does the dramatic spread of velvetbean in recent years represent improved farmer capacity for managing crop production and weed control or the fortuitous, but temporary, solution to a special combination of production problems? Will the farmer experimentation and farmer-to-farmer communication promoted by NGOs lead to improved farmer capacity or simply more efficient technology transfer? How will farmers who learned to use velvetbean from other farmers for weed control in maize respond to changing maize prices or new pest problems? A collapse in maize prices in the Atlantida region of Honduras would jeopardize the velvetbean-maize rotation, since velvetbean does not intercrop easily with annual crops other than maize. Recently, severe infestations of Rottboellia cochinchinensis have been reported in velvetbean fallows in Honduras, leading to land abandonment (Triomphe, 1996). These examples suggest that while farmer-to-farmer networks can be low cost and effective, there is a role for strategic, on-going links between farmer networks and research and extension systems. Scientists and extension staff may lack immediate solutions to problems like maize prices or the invasion of R. cochin-chinensis. Nevertheless, a process of co-learning for improved weed management can achieve several objectives: scientists focused more clearly on integrated approaches to field problems; extensionists directed toward increased farmer capacity for decision-making rather than on technology transfer; and farmers communicating ecological knowledge rather than technological novelties with other farmers.

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