Mineralização do carbono e do nitrogênio de resíduos da indústria fumageira no solo e fornecimento de nitrogênio ao capim sudão

Abstract

The use of agricultural and industrial residues as agricultural fertilizer besides to reduce environmental problems, allows the crop production with lower demand for mineral fertilizers. The tobacco processing in industries produces large amount of residues, called tobacco powder. This powder has potential to use in agriculture, however due the brazilian legislation that restrict its incorporation directaly in soils and excessive dust generation and bad odors it is transformed in compost for agricultural use through solid state fermentation (SSF). The SSF to treat tobacco residues is a recent process therefor are necesary studies about for nutrients supply to crops. The objective of this study was to evaluate the efect of soil type and application mode of tobacco powder and compost on carbon (C) and nitrogen (N) mineralization under laboratory conditions and under field conditions the fertilizer potential of the compost for sudan grass. Was performed a incubation during 100 days, in two contrasting soils to evaluate the efect of the location (incorporated or surface applied) about the C and N mineralization of the powder and compost. The C and N mineralization was greater in the powder than in the compost regardless of the soil type and residue location. In average, 44% C and 20% N of the tobacco powder were mineralized in 100 days and 36% C and 12% N of the compost. The soil type affected of the C and N mineralization only in the initial stage of decomposition and was higher in sandy soil. The mineralization of N from organic residues was not affected by residue location in sandy soil, but in clay soil the N mineralization was higher when the residues were placement on surface. In the field, different doses of compost were applied in soil to evaluate the effect on dry matter (DM) production, on N accumulation by plants and nitrogen use efficiency by plants of sudan grass. Were tested the doses: 0, 11, 22 and 44 Mg ha-1 of compost besides a treatment with mineral adubation, incorporated or applied on soil surface. The aplication on surface resulted in higher productivity and N accumulated when comparated the incorporated of composto on soil. Higher doses resulted in higher DM and N acumulated, however lower efficiency of the use of N. In treatment whit mineral fertilizer the DM production and N acumulatted were similar to the treatment with 11 Mg ha-1 of compost.