The title of the N2Africa project is ‘Putting nitrogen fixation to work for smallholder farmers in Africa’. The internship took place in northern Rwanda and focuses on climbing bean (type of common bean Phaseolus vulgaris). The length and density of bean stakes are important factors in the production of climbing bean, which is the reason to focus on their use. The aim of this work is to increase the knowledge on the use of bean stakes in northern Rwanda. The objective was addressed through interviews with twenty farmers from four wealth categories and five sites, as well as through the collection of quantitative data in several bean fields of the interviewed farmers.
The average stake length was around 2m and generally increased with each wealth category. Stake length was consequently higher in Muko, which might be related to the fact that most farmers in Muko used tripods as staking method. The stake length was surprisingly equal for the different fields of the same farmer (with one exception). All farmers used both pennisetum and wood as staking material and the highest contribution always came from either of them. Focusing on the separate contributions of the different types, the majority of stakes were wood (29 times wood vs. 11 times pennisetum). Also stake density increased substantially with each wealth category, while the distance between stakes decreased. Stake density ranged between 1.95-3.72 stakes m-2. In general, the differences between fields of the same farmer are small.
For the cultivation of climbing beans two systems were in use; the traditional system with random seed distribution and the modern system, in which seeds are sown in lines. The main difference in the use of bean stakes found between the sites is the staking method; mainly tripods at Muko and individual stakes at the other sites. Generally, tripods were used on the hillsides, because the soil is less deep, while lines of individual stakes were more frequently used in the valleys. Most farmers added stakes directly on the day of sowing, but this could also happen four weeks later, depending mostly on the availability of stakes. A large variety of plant species was used as staking material to support climbing beans. The most important stake types were Pennisetum and wood, most frequently Eucalyptus. The preferred stake species of a farmer seemed to depend on which factor he/she focused; pennisetum when a farmer focused on availability and price and wooden when the focus was on strength or a long life length. The majority of the farmers purchased at least part of their staking material. The total annual investment ranged between 1,000 and 100,000 Rwf (equal to 1.67-167 USD). The price for wooden stakes (10-60 Rwf) was always higher than the price paid for pennisetum stakes (5-30 Rwf). The life length of a pennisetum stake in northern Rwanda is 2-4 seasons, while for a wooden stake this is 4-6 seasons. All farmers stored stakes in bundles, close to the house or at least within the compound and if possible sheltered from rain. The most important reasons to replace stakes were insect damage and weather conditions. Therefore, the most desired improvements were fertilizer, a higher quantity of high-quality stakes and insecticides. According to the farmers the three most important constraints to bean production are poor soils, availability and quality of bean stakes and unfavorable weather conditions. Fifty percent of the farmers thought it would be possible to produce their own stakes, without purchasing any. The other farmers saw land scarcity as an insurmountable problem. Most of those farmers first needed to invest in changes. Farmers were asked to describe a perfect bean field. The result is a field with tripods of wooden stakes with a length of at least 3m and a distance of 30-60 cm between stakes and the number of plants being 3-6 per stake.