Additional Nitrogen Fertilization on Soybean via Soil and Leaf at the Reproductive Stage

Abstract

The ability of organic nitrogen fixation (BNF) to supply all the nutrient N in soybeans, considering high productivity, is questioned about the possible need to complement of this nutrient to the culture through other means of supplemental conventional fertilization. In this work the aim was to check the response of soybeans inoculated with bacteria of the genus Rhizobium and Bradyrhizobium, conditioned to supplementary nitrogen fertilization in the reproductive phase, in soil and in leaf. The treatments were the witness (without application of N), 30 and 60 kg of N ha-1, via soil and 2% solution of N, R1 and R 5.3 phases, in a randomized block design with 4 replications, using the soybean cv. Desafio, with the seeds inoculated with bacteria of the species Bradyrhizobium japonicum and Bradyrhizobium elkanii (strains Semia 587 and Semia 5019). The late application of N into R1 and R 5.3 provided increase in grain productivity of 478.6 kg ha-1 and 472.8 kg ha-1, respectively. The application, via soil, N in R1 features better harvest index, when compared to R 5.3. The late application of 2% solution of N, via foliar, provided no increase in productivity of soybean culture.