Yield and economic benefits of common bean (Phaseolus vulgaris) and soybean (Glycine max) inoculation in northern Tanzania uri icon

abstract

  • On-farm experiments were conducted in farmers' fields at 12 different sites in the 2 districts of Moshi and Rombo in northern Tanzania during the 2000-01 cropping season to study the effects of (brady) rhizobial inoculation in combination with P supply on growth and grain yields of soybean and common bean, and to assess the economic returns of these different technologies to farmers. A low level of N was included as an indicator of endogenous soil N status. The treatments included ( brady) rhizobial inoculation, N fertilisation ( 30 kg N/ha as urea), P application [ 26 kg P/ha as triple super phosphate (TSP)], ( brady) rhizobial inoculation + P fertilisation ( 26 kg/ha as TSP) and unfertilised uninoculated control. The study was conducted as a randomised complete block design with each of the 12 farmers' fields as a replicate. At harvest, plant growth of soybean and common bean was significantly (P <= 0.05) greater with ( brady) rhizobial inoculation compared with N and P supply or uninoculated control in the 2 districts. Relative to uninoculated unfertilised plots, grain yields of common bean were markedly (P <= 0.05) increased by 60 - 78% from inoculation alone, and 82 - 95% from inoculation + 26 kg P/ha; with soybean there was 127 - 139% increase in grain yield from inoculation alone, and 207 - 231% from inoculation + P. Thus, the combined application of bacterial inoculants and P fertiliser to field plants of soybean and common bean significantly (P <= 0.05) increased biomass production and grain yield compared with the single use of N and P or ( brady) rhizobial strains. From economic analysis, the increase in grain yield with inoculation translated into a significantly (P <= 0.05) higher marginal rate of return and dollar profit for soybean and common bean farmers in northern Tanzania. With common bean, there was a 66 and 92% increase, respectively, in dollar profit with inoculation at Moshi and Rombo districts respectively relative to control; these profit margins rose to 84 and 102% with provision of supplemental P ( 26 kg P/ha). With soybean, however, the increase in profit with inoculation was much larger, about 140 and 153% at Rombo and Moshi, respectively, and these rose to 224 and 250% with P supply.

publication date

  • 2006
  • 2006
  • 2006