DOSES E FORMAS DE APLICAÇÃO DE REJEITO FINO DA MINERAÇÃO DE ESMERALDAS EM CARACTERÍSTICAS DO SOLO E PRODUÇÃO DE CAPIM MARANDU

Abstract

The use of rock dust, or rock remineralization, can improve the productivity and quality of pastures by enhancing soil fertility and, consequently, animal performance, representing an alternative to the use of soluble mineral fertilizers. This study aimed to evaluate doses of talc-schist mining tailings on soil chemical properties and on morphometric and productive variables of Marandu grass, under irrigation during the dry season. The experiment was arranged in a randomized block design with split plots, where the plots represented the application methods (incorporated or surface-applied) and the subplots consisted of four doses (0, 20, 40, and 60 m³ ha⁻¹) of the tailings, with four replications. The attributes evaluated were: average tiller length (TL), tiller density (TD), number of leaves per tiller (LPT), leaf-to-stem ratio (LSR), dry matter content (DMC), fresh mass yield (FMY), dry mass yield (DMY), neutral detergent fiber (NDF), acid detergent fiber (ADF), soil pH, soil organic matter (SOM), aluminum (Al³⁺), calcium (Ca²⁺), magnesium (Mg²⁺), potassium (K⁺), phosphorus (P), potential acidity (H⁺+Al), total cation exchange capacity (CEC), base saturation (V%), and aluminum saturation (m%). Grass growth and production were evaluated from January 2024 to January 2025, with three assessment periods: May 2024, October 2024, and January 2025, representing the end of the rainy season, the end of the dry season, and the beginning of the rainy season, respectively. Soil properties were assessed at the end of the experiment. In the first evaluation, TD showed a significant interaction between application method and dose (p<0.05), while both TD and DMY differed significantly (p<0.05) for the isolated factor “dose.” TD fitted a quadratic model for incorporated applications and a linear model for surface applications. DMY fitted a quadratic model, initially decreasing up to the dose of 25.79 m³ ha⁻¹, then increasing up to the maximum tested dose (60 m³ ha⁻¹), with a 16.5% increase compared to the control. In the second evaluation, no treatment effects were observed. In the third evaluation, tiller length was influenced by the application method, with higher values observed for incorporated tailings. Ca²⁺ and V% fitted quadratic and linear models, respectively, for the dose factor, with maximum responses at 41 and 60 m³ ha⁻¹. Aluminum saturation (m%) differed significantly for incorporated tailings, showing a 358.53% reduction at the dose of 49.16 m³ ha⁻¹. The use of talc-schist tailings showed promising responses under the conditions of this study and should continue to be investigated.