Biological N₂ Fixation and Mineral N in Common Bean–maize Intercropping or Sole Cropping in Southeastern Brazil

The aim of this work was to assess the effects of N levels and intercropping of two common bean ( Phaseolus vulgaris ) varieties (Carioca and Rio Tibagi) with maize ( Zea mays ) on accumulated N, grain yield and biomass of both crops, and nodulation of common bean inoculated or not with Rhizobium . Two field experiments were conducted simultaneously: common bean–maize intercropping and common bean in sole cropping. Intercropping increased common bean nodulation and biomass, mainly with Rhizobium , but mineral N was deleterious to nodulation. Inoculation also increased the Carioca cultivar yield most in sole cropping (+72%), but N levels did not affect common bean yield in either cultivar. Although intercropping reduced maize grain yield by 17%, the equivalent yield increased by 31%, whilst Rhizobium increased it by 11%. Despite the reduction of maize yield in intercropping, this system was shown to be more economically viable, in particular when common bean was inoculated with Rhizobium .