Researchers from the State University of São Paulo (Unesp) study the application of organic fertilizers, produced from the composting of sludge from sewage treatment, in order to determine the best practices of soil management in crops. Among the investigations performed, there were positive results in the use of fertilizer as an organic source of nutrients for cerrado soil in corn and soybean crops.

The studies, developed by the Study Group on Nutrition, Fertilization and Soil Fertility (Genafert) of the Ilha Solteira da Unesp campus and led by Professor Thiago Nogueira, involve variables such as the search for the most appropriate dose for fertilizer application in plantations, the periodicity and the most effective way of this application, in addition to identifying the crops that present the best returns after the application of the compound.

In one of the stages of the research, developed during the master's project of Adrielle Rodrigues Prates, the data showed that the application of the compound from sewage treatment increased the concentration of micronutrients in soil and leaves, in addition to increasing soybean yield by 67%, compared to the Brazilian average.

"The cerrado soil is a region where fertility is usually low, where the limits and nutrients are low, and what occurs is a limitation in crop production. So [at this stage of the study] the focus was to use this compound as a source of micronutrients, towed with conventional mineral fertilization, and also studying the form of application – in total area or between rows of crops – which would be the best form of application and the best dose", explained Adrielle.

After the application of the compound and sowing of soybean, the researchers sown corn to study the residual effect of fertilizer in this second crop, which also resulted in the benefit of productivity. Corn increased yield by more than 100% compared to the Brazilian average, as Adrielle pointed out.

The researcher explained that the increase in the concentration of micronutrients in the soil, resulting from the use of the compound from sewage treatment sludge, is important because the soil behaves as a reserve of nutrients for the plant.

"If you increase these nutrients to adequate levels, the soil will provide them to the plant. And when the plant is well nourished, with the right levels, it can properly develop its entire cycle and can increase its production, so that it has no limiting, has no nutrient [missing] that is limiting its development, its production", he said.

It assesses the need for a long-term study of this application of the compound, to monitor how the soil will behave and to avoid toxicity events in crops. "It is important, in addition to researching for the best dose and the best way of application, this long-term study, to see how the health of this soil is, how it will get the increase in [nutrient] levels."

In addition to the benefit for plantations, the use of this fertilizer resulting from sewage treatment can mitigate environmental pollution and the volume of organic matter that ends up in landfills. "This whole process brings, in addition to the benefit for agriculture, an environmental benefit. For all the care in the composting process, which eliminates pathogenic microorganisms and makes plant heavy metals unavailable, makes the risk to the environment much lower."

"In addition, sewage sludge is usually disposed of in landfill. It can be dumped into water courses occurring pollution. So, this proper use of the compound [originating] from the stem, through the composting process, applying at the correct dose, it brings a benefit for both agriculture and the environment, because this waste is not being thrown in landfills, in water courses or incinerated, it has an appropriate final destination", explained the researcher.

Source: Canal Rural