John Howieson

The use of rhizobiumRhizobium inoculants for improvement in nitrogen-fixationNitrogen and productivity of grainGrainlegumesLegume has been well established in developed countries. However, the practice is still under-utilized in NigeriaNigeria. NitrogenNitrogen (N) is the most frequently deficient nutrient for crop production, while nitrogenNitrogenfertilizersFertilizers are costly, inadequate, and may not be timely in supply. These make rhizobia inoculants a cheaper, easier and safer option to improve the N2-fixation and productivity of grainGrainlegumesLegume. Inoculant use in NigeriaNigeria was initiated in the 1970s, but still remains very limited. Studies conducted on inoculant use were initially on “US type” SoybeanSoybean (Glycine max (L.) Merrill), which has been found to require specific inoculation with Bradyrhizobim japonicum for optimum productivity. Studies were also conducted on inoculation of cowpeaCowpea (Vigna unguiculata (L.) Walp), but rarely on bambara groundnutGroundnut (Vigna subterranea (L.) Verdc.) and groundnutGroundnut or peanutPeanut (Arachis hypogaea L.). In the 1980s, the International Institute of TropicalTropicalAgricultureAgriculture (IITA) Ibadan, NigeriaNigeria, introduced promiscuous soybeanSoybeancultivarsCultivars; TropicalTropical Glycine Cross (TGx). These genotypesGenes nodulate freely with the indigenous rhizobiumRhizobium population, fix large amount of atmosphericAtmospherenitrogenNitrogen and produce higher grainGrainyieldsYields than the localLocal genotypes. However, some experiments indicated up to 40–45% increases in yieldYields by some of the genotypesGenes on inoculation. Hence, the ultimate solution remains the development of inoculants using highly effective indigenous rhizobia strains for particular crops. The recent efforts of the project “Putting NitrogenNitrogenfixationNitrogen fixation to work for smallholder farmersFarmers in Africa (N2Africa)Africa” towards the promotion of inoculants technology are highly welcomed in the country.