Biocarvão, biomassa e composto do subproduto da indústria cítrica nos atributos químicos e biológicos do solo e no crescimento de alface.

Abstract

Brazil is one of the main orange juice exporting countries in the world. The processing of the orange to obtain the juice, generates a large amount of solid residues, these residues can cause environmental, social and economic problems, their easy fermentation and decomposition, exhale odor and contribute to the proliferation of pathogens and leaching of nutrients such as P. The use of agribusiness residues as a nutrient-rich bioproduct can make a significant contribution to the environment and the sustainability of production. The objective was to produce and characterize the biochar, biomass and orange pomace compound and to evaluate their potential in supplying phosphorus. The characterization of biochar, biomass, composed of orange bagasse, and fractionation of the phosphorus of these products was carried out, as well as the potential as a source of P of the bioproducts, using lettuce as an indicator plant. Biochar (BBL) was produced at 300; 500 and 700 ºC, biomass (BMBL) and orange bagasse compound (CBL), analyzed and tested by adding them to the soil. The BBL yield was higher at the pyrolysis temperature of 300 ºC and lower at 700 ºC. BBLs showed alkaline pH values at all pyrolysis temperatures (9.5 to 11.5). The total content of macronutrients in all products of the orange pomace was in the following order: K> Ca> P> Mg, with K in BBL, produced at 700 ºC, being the highest. For micronutrients the order was: Fe> B> Mn> Zn> Cu> Mo, with the highest Fe value in CBL. The fractionation of the orange pomace in all forms of use showed high levels of P, varying the forms depending on the treatments. Total phosphorus (PT), phosphorus associated with minerals (PAM) and residual phosphorus (PR) were found in higher concentrations in the treatment under application of BBL 700 °C, soluble phosphorus (PS) in soil+CBL, and labile phosphorus (PLAB), adsorbed phosphorus (PAD) in soil + SFS. The application of CBL in the soil positively influenced the development of lettuce plants, with the treatment with the highest averages for all phytometric variables, except for the MVR variable, whose highest average was obtained in the soil + BMBL treatment, however without statistical difference for soil treatment+CBL. Pyrolysis of orange bagasse at 500 °C and CBL produced promising chemical characteristics, showing the potential to be used to improve soil quality. CBL can be used as a more readily available source of P, different from BBL 300 and 500 °C, which presented different fractions and possibly a slower release of P into the soil. Soil+CBL provided a higher concentration of soluble P in the soil. The phytometric variables of the lettuce plants were positively influenced by the treatments soil+BBL 300 °C, soil + CBL, soil+BMBL, when compared to the other treatments. All treatments increased the levels of P in the leaf tissues of lettuce plants, when compared to soil+SFS.