Mucuna has become a byword in the Republic of Benin among farmers and agricultural extension workers, as an example of a soil management technology that is solving a major weed problem as well as helping to restore soil fertility.
It all began in 1986, when IITA and Beninois scientists started on-farm research in Benin on methods to restore soil fertility and --at the same time-- to encourage farmers to participate in the experimentation process, as a means to develop practical, adoptable technologies. One such technology, the cultivation of a ground cover or live mulch, Mucuna pruriens var. utilis enriches the soil with nitrogen. As mucuna spreads over the ground, it also has the welcome effect of smothering young shoots of u speargrass", the noxious weed Imperata cylindrica, which widely infested the impoverished soils of the region.
The popularity of mucuna has led to its adoption by the national extension agency for countrywide application, and to selection by the Global 2000 project for demonstration trials by 500 Beninois farmers. This success is due in large part to the enthusiastic efforts of the participating farmers to develop the technology.
Farmers accepted mucuna after seeing how effective it was in combating two of their main farming problems: restoring soil fertility so that maize yields improved, and halting the rampant speargrass by covering the ground and preventing the weed from receiving adequate sunlight. The farmers' contributions over four years of mucuna research gave them a stake in the results, motivating them to encourage others to use it as a result of their experience.
Evolving project
Concern about declining soil fertility led IITA, early in 1986, to join with the Direction de Recherche Agronomique of the Benin government and the Royal Tropical Institute (KIT) of the Netherlands in a project on "Recherche appliquČe en milieu rČel". The objective was to develop alternative methods to restore fertility by enlisting farmers' participation in a series of on-farm research trials.
Soil fertility had been declining in the Adja Plateau in Mono Province, southern Benin, under growing population pressure. Traditionally, to prevent loss of fertility, farmers in that area had planted 12-to- 15-year fallows with oil palm, which is economically attractive because of the palm wine produced from the trees when the fallows were cleared. However, the increasing demand for food had lengthened the periods of cultivation and shortened the fallows, with the result that soils had become impoverished.
The initial round of experiments involved a set of maize trials planted in farmers' fields, and several researcher-controlled demonstrations of new soil-enriching technologies such as alley cropping, various cover crops, and live mulch. The experiments began in 1986, to be implemented over the 1986 and 1987 cropping seasons. As it turned out, these demonstration fields were to have the greatest impact on farmers' decision-making.
Farmers met periodically with project scientists and technicians, to discuss their experiences in the series of experiments and to participate in selecting new treatments for the coming season. Group discussions were very lively and farmers became well informed even about results from experiences with options which they had not selected.
Their curiosity to hear the impressions of others about the different options seemed to stimulate attendance at meetings. The group became so large that it had to be divided into two, each of which included the full range of options in its scope.
Impressed
In the demonstration plots, the way that mucuna had smothered the ubiquitous speargrass impressed many farmers. Hence, in 1988 and 1989, a number of farmers elected to grow mucuna as a planted fallow crop during the "short season" (so called because it is the shorter of two rainy seasons which are characteristic of the climate in this part of Africa). Some farmers elected to grow pigeon pea (Cajanus cajan) in their planted fallow. The pigeon pea barely grew where soils were very depleted, but mucuna seemed to perform better in similarly poor soils.
The trials confirmed mucuna's value as a weapon against speargrass. Even more important, the trials proved mucuna's capacity to restore fertility to the soil, resulting in greatly improved yields of maize during the following season. The accompanying chart of 1989 results shows that maize yields on plots earlier planted to mucuna were, on average, 80% greater than on continuously cropped land. Far smaller gains were recorded for maize on plots planted earlier to pigeon pea.
For 1990, the scientists and farmers next planned optional treatments for two types of soil conditions which existed: (1) completely depleted fields, and (2) fields still reasonably fertile. Two options for the completely exhausted fields were mucuna and acacia trees, a fast-growing legume which would produce a substantial amount of slowly decomposing litter and high-quality fuelwood.
The mucuna was to be planted one month after sowing maize during the first rainy season, and would grow to a dense cover during the second rainy season. Subsequently, during the dry season, the mucuna would die and forma dry mulch, which would fertilize the next year's first-season maize crop. Mucuna would once again be "relay planted" in this manner, one month after that crop.
The aim was to regenerate soil fertility to an adequate degree after several years of either mucuna cover crops or acacia fallow. Once the fertility of their fields had been restored, the farmers could decide whether to go on to one of the second set of options, in order to maintain soil fertility.
The results for farmers who had chosen mucuna were dramatic. They recorded, on average, a tenfold increase in maize yield (from 200 to 2,000 kilograms per hectare).
Even before those results had become evident, others had begun joining the ranks of the mucuna planters, attesting to its growing word-of-mouth popularity as a soil improver as well as a weapon against Imperata. As a consequence of the demonstrated yield increase, 20 additional farmers with infertile fields chose the mucuna option in 1991, they obtained a threefold increase over the previous year's recruits.
National extension authorities were so impressed with the results that they decided to apply the technology from 1991 in all the agroecological zones of the country where soils are depleted and imperata is a problem. The results of adoption in the current nationwide phase will be studied from 1992, with documentation of the extent of adoption, characterization of areas where it has been successful, and a comparison between areas with characteristics favoring adoption and areas where the technology was actually successful.
Ingredients of success
Behind the success in promoting adoption of mucuna to date, a number of elements can be singled out as being major contributory factors.
Farmers were an integral part of the decision-making process, first of all, and they participated in groups which had been divided according to the types of problems under investigation. Those in the same groups shared similar problems--farmers in the 1990-1991 set of trials had joined discussion groups for either completely depleted fields or reasonably fertile fields. Consequently the groups enjoyed a unity of purpose.
Each group was offered a range of technologies to choose from. Every farmer could accommodate his particular problems among the options, or could discuss with his peers and the scientists how to tailor the technologies to them.
Moreover, farmers had a chance to see demonstration plots showing the effects of mucuna and other technologies before they made a selection. They were not simply told about hypothetical benefits and asked to make a blind choice.
Finally, the dual impact of mucuna in restoring soil fertility and combating imperata appealed greatly to farmers, particularly those with few labor resources. Mucuna's bonus of imperata control had a decisive impact in the widespread adoption of this technology.
For the future, scientists with an interest in on-farm experimentation can draw on a fund of useful experience from the Benin mucuna trials. The farmers showed, in their contribution to refinements in the technologies, the fruitfulness of their participation in experiments which had been so designed as to bring out the benefits they had to offer.
Click on logo to return to the home page