They demonstrate the benefits of using pig wastewater for soy fertilization

In Córdoba, research by INTA and the Chamber of Pork Producers of Córdoba (Cappcor) showed that pig wastewater used as a bio-supplement promoted productive improvements in soybeans. According to the trials carried out in eight consecutive campaigns, it increased from 2,646 to 4,574 kilos per hectare, an increase of almost 1,900 additional kilos.

The results were consistent: Compared to the control plot that never received wastewater, the treatments recorded an increase in organic matter content of almost a point after eight years. Significant differences were also observed in phosphorus – with almost 35 additional parts per million – and a relevant contribution from zinc, considered a key element among micronutrients.

“I highlight these three elements because they allow us to summarize what has been observed: positive changes in macronutrients and also in micronutrients,” said Nicolás Sosa, expert at INTA Manfredi, who is carrying out the studies together with Diego Mathier and Marcos Bragachini.

Improvements in soil physical parameters were also observed. The determination of apparent density, aggregate stability and penetration resistance showed a favorable development in the plots with wastewater application compared to the control.

In this way, the research showed that the pig wastewater acted as an organic additive that could comprehensively improve the soil. “More than a fertilizer that provides one, two or more nutrients, it is a more comprehensive fertilization practice,” Sosa explained.

The main evaluation point is located in the city of Despeñaderos and is installed in the Porcal plant of the Dos Ríos company, which has 1,600 mothers in production. The management system involves treating the slurry in three waterproof stabilization ponds, filtering it via a self-cleaning screen and then spreading it using a central pivot during fallow.

In addition to changes in soil properties, the tests allowed the impact on crop production to be assessed. During the eight campaigns, three for corn and five for soybeans alternated. The results showed positive reactions in both cultures, although with different behavior.

For soybeans, the last campaign showed a significant increase: control yielded 2,646 kilos per hectare, while the application of 25 millimeters of wastewater without mineral fertilization reached 3,830 kilos per hectare. In the treatments combining wastewater with triple superphosphate, yields reached 3949 and 4574 kilos per hectare.

“We observed that there is an additional effect in soybeans when they are supplemented with mineral phosphorus, even if the soil already has high levels of this nutrient,” explains Mathier.

However, the reaction was different for corn: dosing 25 millimeters of wastewater without mineral fertilization was established as the most economically efficient option. So while mineral fertilization increases the reaction with soybeans, the optimal approach for corn was simply the application of wastewater.

Regarding management recommendations, Sosa emphasized that applications should always be based on balanced nutrient distribution. The nutrient supply of the soil – determined through laboratory analyzes -, the composition of the wastewater and the requirements of the respective crop are taken into account. “A balance makes it possible to adjust the application dose and avoid problems because the demand for wheat, barley, corn or soybeans is not the same,” he noted.

Marcos Torres, member of the CAPPCOR board – which brings together 30 companies and concentrates 50% of the provincial production – pointed to the good results obtained by INTA Manfredi in Villa María del Río Seco, in the north of Córdoba, with the same line of research.

“In our farm in Villa María de Río Seco, we have obtained 7,000 kilos more corn per hectare in four campaigns thanks to the addition of pig waste. These additional kilos correspond to a complete production campaign,” he said. “For phosphorus, we initially had levels of 40 parts per million. After five years of manure application, this level increased to almost 65 parts per million,” he added.

The producer emphasized the value of public-private coordination: “If we had not had the connection with INTA, our studies would lack scientific rigor. INTA Manfredi gives us seriousness and objectivity. It is a reference for livestock waste and irrigation systems that we also use to direct wastewater to the plot.”

“These studies allow us to lead a line of research on a topic with high demand and great potential for study,” Sosa said. “Providing information is crucial to enable producers to make decisions in their own operations and avoid management errors by adapting their practices based on the experience gained in the trials,” he concluded.