​Researcher discovers technique that increases soybean productivity

The Unesp master's procedure is the first information from the scientific community

09.06.2017 | 20:59 (UTC -3)
Fabiana Manfrim

Researcher Luiz Gustavo Moretti, from the Faculty of Agricultural Sciences (FCA) at Unesp, in Botucatu, discovered through his master's degree a new way to increase the profitability and production of soybeans. The technique consists of using, in two stages, biological nitrogen fixation through bacteria Bradyrhizobium japonicum. At first, when soybeans are sown, and then, after 50 to 70 days, when the plant is already developing.

The master's degree: “Optimization of Biological Nitrogen Fixation in soybeans as a function of re-inoculation in coverage under direct planting” was supervised by professor Edson Lazarini, from Unesp in Ilha Solteira, with the support of undergraduate and postgraduate students, and co-supervised by researcher Mariangela Virgínia, from the National Soy Research Center (Londrina/PR), from Embrapa. The project received a grant from the Sustainable Agriculture Foundation - AGRISUS.

“Topping inoculation, that is, spraying on something, is a possible new practice to be used by rural producers (soybean farmers), which is the adoption of a second inoculation of the bacteria during the soybean cycle. The first inoculation is already an established and consolidated practice, what we call “inoculation via seed” during planting, carried out in the treatment of the seeds to be used. Cover inoculation, which is what I researched, is a practice added to the previous one, which consists of a new inoculation at a determined phenological stage. We sprayed the bacteria again, with a jet directed/localized to the soil, during the plant's development, and thus tried to increase its population, with the expectation that a second population of active bacteria could result in a greater amount of nitrogen available to the plant” , explains Moretti.

Also according to the researcher, the bacteria benefits from staying in the soybean roots (the lifespan of each nodule is around 40 days) and also benefits the soybean by making nitrogen available. “The bacteria does not cause any harm to it and makes soybeans favored by the availability of this nutrient, which is required in greater quantities during its cycle”, he adds.

He explains that the technique will establish a new population of bacteria in the soil and will make the soybean plant respond successfully to it. “However, the soil must have high humidity for this bacteria to be incorporated. This new nodulation will be active in the grain filling phase, where a large amount of nitrogen is required, and can result in increased grain productivity”, he warns.

Soybeans, which take around 120 days to develop, are cultivated on a larger scale in Brazil and the United States. In the USA it is produced through nitrogen fertilizer. In Brazil, the technique used is that of bacteria, as it is specific to tropical soils.

For the researcher, the economic potential of this technology is excellent, because the cost of the inoculant (bacteria) is minimal, compared to its return on crops. “It is necessary for each producer to make their adjustment, each one in their production system, remembering that most of the time, soybeans are produced in a rainfed system (without irrigation), so it must monitor soil humidity and rain forecast for this practice to be efficient. For inoculant producing companies, it is a new window on the market.” “Your economic return is very viable, as you will be working with the culture’s greater potential. Per hectare, nitrogen fertilizer costs are around 1.100 reais. Inoculation costs around 20 reais”, he concludes.

He points out that the bacteria is very sensitive to temperature and light, which is why the soil needs to have high humidity, or rain forecast for the next few hours, or even have an irrigation system. This way the bacteria will not remain on the surface of the soil where it could die due to possible adverse weather conditions.

Moretti concludes that the choice of theme has to do with the importance of the area: “It is an area in full expansion. We believe that microorganisms will guarantee new horizons for agriculture. And later, due to the size of the soybean production chain in Brazil, being the first World Exporter, and second Grain Producer. It is the crop with the largest area sown annually in the country, over 32 million hectares, and as it is a commodity, has great importance in the trade balance”.

Fabiana Manfrim

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