Crescimento de forrageiras em substrato remanescente da mineração de bauxita em Poços de Caldas

Abstract

The recovery of soils degraded by mining activities, aiming for productive and environmental sustainability, often involves the replenishment of organic matter. Therefore, the use of organic waste in fertilizer management in these areas can combine organic matter replenishment with the reduction of the impact generated by the improper deposition of organic waste in the environment. The use of high-yield forage grasses may represent a viable alternative for productive diversification in these areas; however, it requires special attention to their nutritional management, especially during the establishment phase. Thus, the objective of this work, presented in two subsequent chapters, was to evaluate the establishment of forage grasses considered to have medium to high yield in the remaining substrate of bauxite mining, with the application of conventional chemical fertilizer and organic fertilizer obtained from vermicomposting of shimeji mushroom production residues. In the first chapter, the morphogenic and productive rates of the Urochloa brizantha cv. Marandu species were evaluated. In the second chapter, the morphogenic and productive characteristics and physiological responses of Megathyrsus maximus cv. Mombaça, as well as soil microbiological parameters, were assessed. In Chapter I, the application of vermicompost led to an increase in levels of potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg), zinc (Zn), and pH in the studied substrate. Fertilization based solely on chemical fertilizers did not promote increases in morphogenic and productive rates up to 90 days of initial growth. In Chapter II, vermicompost fertilization resulted in increases in morphogenic rates and production in the first 90 days of growth. Doses of 20 and 40 t ha-1 of vermicompost, along with conventional fertilizer and micronutrient treatment, showed the best physiological response in Mombaça grass. However, high initial doses of vermicompost (60 t ha-1 ) may cause a reduction in soil carbon and microbial activity, indicating potential long-term sustainability loss. The results emphasize that the establishment of high-yield pasture in these areas is severely compromised if fertilizer management is limited to liming and/or conventional chemical fertilization. In addition, they indicate the potential use of vermicompost derived from shimeji mushroom production residues in building soil fertility in the process of recovering areas degraded by bauxite mining in the municipality of Poços de Caldas-MG.