Lixiviação de nitrato e carbono orgânico dissolvido em solos arenosos com biocarvões e resíduos in natura

Abstract

The intensity of agroindustrialization in the state of Mato Grosso, as the country's largest producer of grains and fiber, generated a demand for sustainability and reduction of environmental impacts in the agricultural production chain. To reduce the impacts of agroindustry residues, biochar is cited as a promising alternative. The objective of this work was to evaluate and characterize the residues of agro-industries in its in natura and biochar form, capacity to release and retain nitrate and dissolved organic carbon in sandy soils (Oxisol and Arenosol). Biochar was produced from cotton shell and pig solid waste, submitted to a slow pyrolysis (550 °C for 2 h). The experiment was analyzed using a randomized block design. The experiment was carried out in 20 cm columns, where only the 0-5 cm layer were mixed with the biochars, in a single dose of 10 Mg.ha-1 , the in natura residues were mixed according to their gravimetric yield of biochar production in the doses: 35.71 and 19 Mg.ha-1 , cotton shell and swine manure, respectively. The columns were saturated with 250 ml of distilled water and the first reading was carried out. For the following weeks, 50 ml of water were added to collect the leachate for 9 flushes. The concentrations of COD and nitrate were analyzed by UV-Vis spectroscopy, to interpret the characteristics of the COD. In natura materials tend to release nitrate in greater amounts compared to their respective biochars, while they present higher total N in the soil, as for the release of COD, plant material biochar tends to increase, while manure biochar does not differ from in natura material, while total C values do not differ between soil and material condition.