Abstract

The growth of tree legumes in degraded areas must be preceded by assessments of nodulation ability of naturally established rhizobia populations since such information contributes to defining the species which can be planted for recovering disturbed areas. The aim of this study was to evaluate the growth and natural nodulation of “sabiá” (Mimosa caesalpiniifolia Benth.) and leucaena (Leucaena leucocephala (Lam.) de Wit.) in soils of the Brazilian semiarid area under different systems of land use: native vegetation (locally called caatinga) and areas with different agricultural systems (a monocrop system and an intercropping with various species). For each species, a greenhouse experiment in randomized block design was realized, using soils of different types (Luvisol and Ultisol), with 4 replicates. The results evidentiate significant differences in the evaluated growth characteristics (height, leaflet number and shoot diameter) of M. caesalpiniifolia, that have displayed lower plant growth when cultivated in the Luvisol under conventional system. Plant growth, nodulation and total N accumulation in both seedling tree legumes increased in Ultisol under the different systems of land use. L. leucocephala showed higher potential of biological nitrogen fixation and nodulation effectiveness promoted by indigenous rhizobia.

Key words:  Biological nitrogen fixation, indigenous rhizobia, symbiosis, sustainable agriculture.