A soybean crop experiment using samples from a sandy Dark Red Latosol was conducted in a greenhouse at the Universidade Federal de Uberlândia, Minas Gerais, Brazil from July/1996 to February/1997, to evaluate the effects of inoculation and subsoil compaction on the shoot dry matter production (ADMP), root dry matter production in the superior ring of the column, and nitrogen absorption and concentration in soybean shoots.. The treatments were set in a 2 x 3 x 4 factorial design and corresponded to sterilized and non sterilized soil (using 250 cm³ m-3 methyl bromide), three strains of Bradyrhizobium japonicum soil native, SEMIA 5079 and SEMIA 5080 inoculated in seed soybean and four levels of compaction (bulk densities of 1.15, 1.30, 1.45 and 1.60 kg dm-3) applied with a hydraulic press on the soil placed in a central ring of a column made by three 15 cm diameter PVC rings. Forty-seven days after germination, the plants were harvested, dried and weighed. The roots of the superior ring were harvested and measured. The ADMP of soybean increased in the sterilized soil and inoculation with strain SEMIA 5080 at densities 1.15 and 1.30 kg dm-3. For higher densities, the strains studied did not have any effect. The compaction caused linear reductions-either in nitrogen concentration and in shoot dry matter production of the non sterilized soil, - and parabolic reduction, with the highest production at 1.35 kg dm-3 density in the sterilized soil. Nitrogen concentration in the shoots was lower with inoculation of the strain SEMIA 5079 in sterilized soil, with no difference among treatments in non-sterilized soil. A greater root production in the surface layer (ring) occurred in non-sterilized soil with seeds inoculated with Bradyrhizobium japonicum. In sterilized soil, the greatest production occurred due to inoculation of the strain SEMIA 5079. Compaction caused an increasing linear effect in root growth in non-sterilized soil and parabolic, with greatest growth at 1.45 kg dm-3 density in sterilized soil.
compaction; bradyrhizobia; nitrogen fixation; roots system