Abstract:
Decline in soil fertility has become a serious problem in Sub Saharan Africa (SSA) region. It
affects all spheres of social and economic life in the region. Among the countries in SSA,
Ethiopia has the highest rates of nutrient (N and P) depletions mainly due to the low nutrient
input and high biomass removal. An experiment was conducted to determine the effects of
selected grain legumes (faba bean and soybean) on soil fertility improvement. Soil samples were
collected in a transect walk from Dedo and Tiro-Afeta districts of south western Oromia
Regional States, Ethiopia. Six composite soil samples from each transect (based on elevation)
were collected at the depth of (0-30cm). The soil samples were collected from fields that are
known to grow continuous cereal-cereal at least for the last three years. A pot experiment was
therefore conducted under greenhouse conditions in RCBD with three replication on soils
obtained from Dedo and Tiro-Afeta transects. Soil physic-chemical properties were studied
before and after sowing. All plant related data from crops were recorded at 75% flowering
stage. The effect of different elevation levels showed that soil properties before planting were
significantly (P<0.05) for all studied parameters. The effect was observed by measuring plant
Ht, DMP, NN, ANF, Ndfa, soil N and P contents, pH after planting and N and P contents of
plant dry matter for each faba bean and soya bean. The study showed a significant (P<0.05)
difference and positive correlation between all treatments with soil available P before planting
except Ndfa for both crops. Faba beans recorded the highest value for the studied parameters
under Dedo soils than soybean for the same parameters. Similarly, soybean recorded the
highest value under Tiro-Afeta soils than fababean for the studied parameters. Thus, this study
concludes that firstly growing fababean crop on the Dedo soils and soya bean crop on the TiroAfeta soils would improve soil fertility quickly and inexpensively thereby crop productivity can
be enhanced.
