Agriculture is the major engine of Rwandese economy, accounting for about 40% of the
GDP, 85% of employment and 80% of exports. Known as “meat for the poor”, beans
constitute a predominant source of proteins in Rwandese diet since they supply 65% of
national dietary proteins compared to 4% from animal sources. However, the on-farm bean
productivity is about 0.8 – 1.0 tons/ hectare which is quite low compared to 5 tons/hectare
that is achieved under optimal management conditions. The aim of this study was therefore
to determine the effect of cattle manure, mineral fertilizer and Rhizobium inoculation on
production of climbing beans and subsequently the soil properties in Burera District. The
experimental design was a split plot in completely randomized design (CRD) with two main
plots (with and without Rhizobium inoculum); four sub-plots (Cattle Manure, DAP, Cattle
manure + DAP, untreated control) with quantities applied at single level for each treatment,
i.e. 20t/ha for Cattle manure, 50 kg/ha for DAP and 100 g of inoculum which was mixed with
15 kg of beans. The experiment involved 8 treatments which were replicated three times to
give 24 plots. The mean bean grain yields from inoculated treatments and non-inoculated
treatments showed statistically significant difference (P< 0.0001), that is 3900 kg/ha from
inoculated plots and 2946 kg/ha from non-inoculated. Statistical significant differences were
also found among treatments (P<0.0001) with the highest mean yield of 4782 kg/ha obtained
from treatment Inoculum + DAP + Cattle Manure against 2640 kg/ha from untreated
(control) plots. The mean number of nodules was significantly different (P< 0.0001) between
inoculated (60 nodules) and non-inoculated (15 nodules) plots. The highest number of
nodules (95) was recorded from plots that were treated with Inoculum + DAP + Cattle
Manure and the lowest (14) in the untreated control plots (P<0.0001). Regression analysis
between yield and nodule number showed a coefficient of determination R2
of 0.8 and a p
value of < 0.0001, which confirmed the dependence of the yield on nodules number. In terms
of cost-benefit analysis, in the highest yielding treatment (I+FYM+DAP) scenario, a farmer
is likely to earn around 1,330 USD per season per hectare; while in the middle and lowest
yielding treatment (I and UNTREATED CONTROL), the farmer is likely to lose 43.8 USD
and 388 USD per season per hectare, respectively. On the effect of treatments on soil
chemical properties, no tangible changes were observed in pH, CEC and organic matter at the
end of season. According to these results a combination of mineral fertilizer, inoculum and
cattle manure application gave the best results in terms of bean yield, nodulation and nitrogen
uptake and therefore could be better considered for recommendation to climbing bean
growers in the region.