Fertilizante biológico e resíduo orgânico na disponibilização de nutrientes no cultivo de banana e atributos químicos e biológicos do solo

Abstract

Banana farming is an agribusiness with great potential within the scope of Brazilian fruit growing, and requires large quantities of fertilizers to maintain adequate levels of macronutrients and achieve satisfactory yields. The use of biological fertilizers and organic waste is an efficient option in large agricultural production and a sustainable alternative. Therefore, the objective of this study was to evaluate the use of a biological fertilizer based on phosphate and potassium rocks combined with sewage sludge in a program for making nutrients available in the cultivation of Pacovan bananas. The field experiment was implemented at the UFRPE Sugarcane Experimental Station, located in the municipality of Carpina - PE. The test was conducted in a randomized block design in a subdivided plot scheme, where the plot was considered: collections (time); subplot: treatments and subplot: waste. Four fertilizer treatments (two doses of biological fertilizer; soluble fertilizer - NPK and the control - humus), with and without application of waste - sewage sludge. The experiment was carried out for 2 years, and in this period, three collections of soil and two collections of plant material were made, chemical analyzes of the soil (pH, P, K, Na, Ca, Mg, COT and MO) and of plant (N, P, K, Ca and Mg), and microbiological (BMS, RBS, qCO2 and qMIC) and biochemical analyzes of the soil (soil enzymatic activity). The concentrations of P, K, Ca and Mg in the soil and in the plant were influenced both by the presence of fertilizer treatments and by the applied residue, showing significant differences in all evaluated collections. The biological fertilizer based on rocks increased the concentration of macronutrients in the soil, mainly the contents of P, standing out from the conventional soluble fertilizer. The sewage sludge stimulated the BMS reflecting positively on the enzymatic activity and the values of RBS, qCO2, and qMIC, however, the high Ca concentration caused an imbalance of exchangeable bases in the soil solution. The highest concentration of macronutrients in the soil and in the plant was achieved by applying biological fertilizer next to the sewage sludge. In view of the results found, the recommendation of biological fertilizer in interaction with sewage sludge can be an efficient and sustainable alternative to conventional soluble fertilizers for the cultivation of Pacovan bananas, requiring a previous chemical characterization of the sludge since it can present a high concentration of Ca if treated with CaO, taking care that the applied amount does not cause the imbalance of exchangeable bases in the soil solution.