Impacts of sugarcane vinasse and zeolite loaded with vinasse nutrients on a typical tropical soil properties

Abstract

The intensive use of vinasse in fertigation can cause adverse environmental impacts due to its high organic matter content and acidic pH, despite its nutrient content, including potassium, nitrogen, and phosphorus. In this context, strategies that promote the recovery of nutrients from vinasse and its more controlled application, such as the use of zeolite enriched with vinasse-derived nutrients (ZV), are promising alternatives. This study comparatively evaluated the effects of applying sugarcane vinasse and zeolite with nutrients recovered from vinasse on the fertility of a typical tropical soil, such as an Oxisol. Natural zeolite samples (1 to 4 mm) adsorbed nutrients from vinasse by column percolation until saturation, recovering 44.22 mg g^-1 of K⁺ and 3.06 mg g^-1 of NH₄⁺. Column tests were then conducted to evaluate the application of raw vinasse and nutrient-loaded zeolite (ZV) in soil. When added to the soil, vinasse increased K⁺ and Ca²⁺ concentrations by 20x and 1.5x, respectively, whereas ZV increased them by 7x and 6.2x. The Ca²⁺ ions released by ZV displaced H⁺ from the colloidal exchange sites of the soil, raising its pH from 4.1 to 5.6, whereas the addition of vinasse increased the pH of the soil only to 4.7 due to the high level of organic acids. Consequently, base saturation (V) of ZV and vinasse soils increased from 10% to 79% and 41%, respectively. ZV improved soil fertility more than vinasse since V>50%, without increasing organic matter. The direct use of vinasse, although beneficial in the short term, poses environmental risks from nutrient leaching and soil acidification. In contrast, the use of ZV can increase soil nutrient availability and promote their gradual release, making this process a more sustainable alternative for agricultural management.