Tephrosia Fallow Management in Cameroon

[Editor: In Amaranth to Zai Holes: ideas for growing food under difficult conditions page 203 we described how tephrosia (Tephrosia vogelii), a plant used on contour barriers in southern and eastern Africa for erosion control, was also being used to make an insecticide. Stefan Cherry, who just received his masters from Cornell University, shares additional insights from a community in Cameroon where it is an integral part of the farming system.]

Oral, painted, and written accounts tell how the first of the Kom people to settle in the Northwest Province of Cameroon followed a large snake up through the winding valleys, along the mountain sides to the top of Laikom, a mystical, mountain-perch. There the chief’s palace was built and has sat for approximately two centuries. Today, the Kom ethnic group has a population well over 150,000 people and covers an area of about 650 to 800 square kilometers.

With this rich cultural tradition comes a similarly interesting agricultural history. This includes the development of a widely used but little studied indigenous fallow management system using the biannual, woody legume, Tephrosia vogelii. As part of a global initiative studying indigenous upland fallow management systems, I returned to this spectacular part of Central Africa, where I had previously worked as an agroforestry extension agent with the Peace Corps. I spent five days working with a number of women’s farming groups, farmers, government extension agents, and field staff from an integrated conservation and development project (ICDP), called the Ijim Mountain Forest Project, conducting an initial characterization of the tephrosia fallow system. Using a number of participatory rural appraisal (PRA) techniques (including community mapping, transects, matrix ranking, farm/fallow inventories and others) we looked at five communities ranging in elevation from 1,000 to 2,500+ meters above sea level.

Before the women of Kom started managing the current species of Tephrosia vogelii (known locally as Tekoin-nya) within their rotational fallow system, they used a stunted species of tephrosia that did not provide as much leafy and woody biomass. Before that, an even smaller legume locally known as Alang (Crassocephalum mannii) was used. These other legumes, as well as a local variety of Sesbania spp., are still found in the region. However, since the early to mid 1950s when Tephrosia vogelii was introduced from the neighboring Nso region, it is estimated that more than 70 percent of Kom farmers have been actively managing this useful legume as an integral part of their farming system.

Farmers say that the primary benefit from tephrosia is its use as a green manure for improved soil health. Secondary benefits of the leaves include fish poison, traditional medicine, crop protection against aphids, and treatment of diarrhea in chickens. The woody stems are used as bean poles and stakes for yam production. More importantly, the stems provide a major source of cooking fuel.

Farmers felt strongly that the fuelwood acquired from the fallow system significantly reduced pressure on the montane forest above their communities. Tephrosia also serves to create shade on the farm to protect infants from the sun and is sometimes planted to create a temporary live fence around compounds and gardens. When asked about using tephrosia as a green manure and its effects on soil, the women not only discussed its importance in fertility replenishment for sustainable maize yields; they also alluded to improved soil physics with its impact on soil structure and tilth, particularly noticed during land preparation. They praised tephrosia for its ability to reduce erosion on steep, hillside farms and to suppress noxious weeds like spear grass (Imperata cylindrica).

When asked about the major drawbacks of tephrosia, the women mentioned that goats eat it when it is planted near compounds; it is susceptible to weevils and, in some cases, there is not enough seed when the plant is not allowed to reach maturity due to increasing land pressure.

The fallow system works most effectively on a three-field rotation. Farmers typically interplant tephrosia on one field in March with the first cycle of corn, beans and potatoes; they thin the young plants during weeding and allow the tephrosia to dominate the field after harvesting the maize in August. In a second field, the tephrosia planted in the previous year has established a thick canopy of leaves, covering the soil and serves to suppress weeds. In June, the farmers clear a third field of tephrosia, planted two years previously, harvest the fuelwood, incorporate the green manure, and cultivate crops in the second cycle of the eight month rainy season.

This allows for two cycles of crops each year, with one field always in fallow, one coming out of fallow, and one going into fallow. A small number of farmers are starting to experience the pressures of increasing population and decreasing land availability. However, most women interviewed are planning to continue practicing this indigenous method of fallow management and to pass the knowledge to their daughters. The few who do not have sufficient land to fully take advantage of the tephrosia system have expressed interest in experimenting with incorporating perennial legumes into their farming systems. While in the region, I linked these farmers with conservation and development field staff to facilitate this experimentation.