Resumo

PADRON, Learsy et al. Isolation of nitrogen-fixing and phosporus-solubilizing strains in alfisol soils of Venezuela. Rev. Mex. Cienc. Agríc [online]. 2012, vol.3, n.2, pp.285-297. ISSN 2007-0934.

In order to evaluate the potential of soils in the Middle Valley of Yaracuy River in Venezuela for the production of biofertilizers, nitrogen fixed strains (FBN) and phosphorus-solubilizing strains (SF) were isolated in soils subjected to different management conditions. For this, rizhosferic samples in six different land uses were taken in April, 2010. Sugarcane (Sacharum officinarum), maize (Zea mayz L.), pawpaw (Carica papaya), grass (Brachiaria decumbens) and a forest area were sampled. Bacteria FNVL and SF were isolated using Ashby and Pikoskaya, respectively. Chemical and physical properties were evaluated in all soils to determine the relationship between them and the development of the strains. Results showed that Fn developed better in grass and sugarcane, with 20 and 10 strains respectively, indicating that FNVL strains developed better in uses with low amounts of organic matter or intensive management. The greatest number of SF bacteria was found in land uses with a higher amount of phosphorous (papaya), with 13 colonies, or in uses with adequate physical conditions for the growth of microorganisms (natural forest), with 10 colonies.

Palavras-chave : biofertilizers; fertility; sustainability.