Adubação mineral e organomineral: incubação em solos contrastantes e respostas do cafeeiro

Abstract

This thesis comprises a review and two experimental studies on nutrient management in Coffea arabica L., relating soil processes, plant growth, enzymatic activity, and yield. The review addresses nutrient functions, constraints imposed by acidity, texture, and cation exchange capacity, and redox markers, with emphasis on hydrogen peroxide (H₂O₂), lipid peroxidation (PL), and antioxidant enzymes. In the incubation assay, one powdered mineral fertilizer (M.f.) and two poultry-litter organominerals, one powdered (OM.f.) and one pelletized (OM.p.), were applied to sandy and clayey soils and evaluated at 15, 90, and 150 days. In the initial phase, soil type was the main factor affecting pH, exchangeable bases, and acidity. In the final phase, the interaction between source and texture became more evident, with greater P and K persistence in the sandy soil under organominerals and improvement of acidity-related attributes in the clayey soil, mainly under the powdered formulation. In the field experiment, three sources, one conventional mineral fertilizer, one poultry-manure organomineral (OMef), and one filter-cake organomineral (OMtf), were combined with four rates of an organic compound based on poultry waste. These sources altered soil chemical attributes, modified plant growth, adjusted the antioxidant system, and increased first-harvest yield. OMef promoted greater initial availability of P and exchangeable bases, whereas OMtf increased stem diameter and the emission of plagiotropic branches. Rates between 4 and 6 t ha⁻¹ strengthened antioxidant activity, and yield increased linearly, with an estimated gain of 308.3 kg ha⁻¹ of coffee beans per ton applied. Overall, the results show that soil texture, organic matrix, and fertilizer physical form control nutrient persistence, redox adjustment, and early crop performance.