FERTIGATION WITH ENRICHED VINASSE: A STUDY OF THE IMPACT ON PRODUCTIVE SOIL IN THE SHORT TERM

TORRES MARIELA ANALÍA; LACOSEGLIAZ, MARIANO JOSÉ; RAIMONDO, ENZO EMANUEL; ANGELICOLA, MARÍA VIRGINIA; PAJOT, HIPÓLITO F.; CARLOS G. NIETO PEÑALVER

Los Cocos, Córdoba

Congreso; XVII Congreso Argentino de Microbiología General; 2022

Vinasse, a byproduct from the sugar-alcohol industry, is a brown effluent with an acid pH, high chemical and biological oxygen demand and a high content of mineral salts. 13 liters ofpolluting vinasse are generated from every liter of ethanol. Legislation allows the use of vinasse to irrigate sugarcane crops or non-productive soils. This activity, known as fertigation, can enrich the soil providing minerals, organic matter and important elements including nitrogen and phosphorus. However, uncontrolled fertigation has detrimental effects: salinization, acidification and alteration of the soil microbiota. According to the circular economy, it is important to consider new strategies to increase agricultural production, to diversify industrial production and to reduce the environmental impact. Considering this model, we propose the use vinasse as culture medium for the growth of microorganisms of agricultural relevance. The objective of this work was to determine the impact in short term in the soil of fertigation with spent vinasse used as a medium for culturing bioinoculants. 55% vinasse was used for the growth of Trichoderma harzianum MT2 (T-MT2) alone and in co-culture with Pseudomonas capeferrum WCS358 (P-WCS358) or Rhizobium sp. N21.2 (R-N21.2). Subsequently, the cultures were gauze-filtered and the residual vinasses were used to irrigate soil not previously fertigated. Irrigation was repeated twice in the amount and frequency recommended by EEAOC. After 21 days, the physical-chemical and microbiological characteristics of the treated soil were determined. The results showed pH and toxicity identical when irrigated with water, control vinasse and residual vinasse. Increases in conductivity and salinity were observed when irrigated with control and residual vinasse. Catalase activity and FDAhydrolysis showed no variations, while urease showed large differences between water and vinasse; treatment with residual vinasse showed intermediate values. Total heterotrophic counts with water showed the lowest values. In the case of vinasse and residual vinasse, slight increases were observed, though only significant with residual vinasse from the T-MT2+R-N21.2 culture. Finally, the average metabolic diversity (BIOLOG EcoPlates) with control and residual vinasse from T-MT2+R-N21.2 presented the highest values. In opposite, the soil irrigated with water produced the lowest values. In general, the soils irrigated with residual vinasses enriched with microorganisms showed similar physico-chemical characteristics to the vinasse irrigation and better microbiological characteristics than the water irrigation. These results indicate that fertigation with vinasse utilized for the culture of agronomically important microorganisms does not damage the soil properties in short terms. At the same time, they give added value to a problematic effluent obtaining at the same time a new product that could be applied to the soil in an environmentally friendly way.