Inoculant reduces nitrogen use in corn

An experiment carried out at Embrapa Amazônia Oeste(AM) demonstrated that the inoculation of the bacteria Azospirillum brasiliense in corn seeds for cultivation on dry land, allowed savings of 20 kg of nitrogen per hectare and a yield that was 104% higher than the average for the crop in the state of Amazonas.

In experimental crops in Amazonas in which treatment with the inoculant was used on the seeds, the average yield was 5.359 kg per hectare, while the average productivity of corn crops in Amazonas is 2.626 kg per hectare, according to the Brazilian Institute of Geography and Statistics (IBGE).

Inoculation technology with azospirillum in corn was developed by Embrapa and is already used in several regions in Brazil, contributing to increased productivity and reduced crop costs. “This is the first time that this product has been evaluated in research with corn in Amazonas”, says Embrapa researcher, Inocêncio Oliveira, who carried out experiments in an area of ​​terra firma, in a yellow latosol, in Amazonas with the cultivation of the corn variety BRS Caimbé and the hybrid AG 1051, under a direct planting system, with evaluation of two harvests. Embrapa researchers, Aleksander Muniz and José Roberto Fontes, and the professor at the Federal University of Amazonas (Ufam), Bruno Pereira, also participated in the work.

In the research, it was found that the inoculation of seeds with Azospirillum brasiliense increased corn yield, both in plants not fertilized with nitrogen fertilizer and in those that received nitrogen in top dressing. “The beneficial effect of inoculation with diazotropic bacteria is due to the production of growth-promoting substances, solubilization of phosphates, increased plant resistance to stress and the biological fixation of nitrogen itself", explains Oliveira.

The researcher says that, in the case of corn, the fixation process can partially meet the plant's demand for the nutrient, which is why it is necessary to supplement it with top dressing to achieve better yield, as verified in the experiments. Top dressing on corn is carried out approximately 20 and 40 days after planting.

In the experiment carried out in Amazonas, when only the inoculation of seeds with Azospirillum brasiliense, without subsequently using top dressing, there was a productivity gain of 1.000 kg/ha in relation to the plantings carried out, under the conditions of the region, which represents 38% greater than in crops without nitrogen. In another situation, in which inoculation was carried out with the bacteria Azospirillum brasilienseat sowing and if the recommended doses of nitrogen were used in top dressing, the gain in productivity was more than doubled (127%) compared to cultivation without nitrogen fertilization.

According to Oliveira, the inoculation of seeds with Azospirillum brasiliense associated with nitrogen fertilization in top dressing, the corn yield increased by around three thousand kilos per hectare in the experiment. Comparing the performance of the cultivars used in the research, the results of the hybrid were 47% superior to BRS Caimbé in all evaluations carried out.

R$1,2 million in Amazon savings

The scientist highlights that even using top dressing, inoculation with the bacteria allows savings of 20 kg of nitrogen per hectare, when sowing. “Considering the cultivation of 8.100 hectares of corn in the state of Amazonas in 2018, according to Conab, and the saving of 20 kg of nitrogen per hectare from the use of the inoculant during sowing, there is a reduction of 162 tons of nitrogen or 360 tons of urea”, he exemplifies. This saving would represent approximately 1,2 million reais annually, considering the cost of nitrogen fertilizer in Manaus (AM), according to the researcher's estimate.

“Inoculation with Azospirillum brasiliense it can be a sustainable alternative for supplying nitrogen to corn crops in tropical regions, in addition to saving costs in corn production, especially with chemical nitrogen fertilizers”, highlights Oliveira.