Potencial de aquecimento global em solo adubado com dejeto líquido de suínos

Abstract

The objective was to evaluate the emission of greenhouse gases (CO2, CH4 and N2O) to the atmosphere after the application of pig slurry (PS) and mineral fertilization in soil cultivated with Tifton-85 grass. The experiment was carried out at the experimental station of the Rio Verde Foundation, in the municipality of Lucas do Rio Verde-MT. The experimental design was randomized blocks, containing five treatments and four replicates. The treatments consisted of four doses of pig slurry (PS) applied to each cutting cycle of the tifton-85 grass (approximately 30 days) and a treatment without application of PS and with mineral fertilization. Automated CO2 efflux measurements were performed using a high-precision infrared gas analyzer (model LI8100A) after PS applications in the control and PS applications in the period from 09/27/2014 to 2/21/2015. Continuous monitoring of soil temperature (ºC) and soil volumetric moisture (cm3 cm-3 ) was also performed. GHG emissions (CO2, CH4 and N2O) were evaluated through static chambers, with the GHG concentrations determined by gas chromatography, being performed in two periods, 1st period between 03/18/2015 and 04/20/2015 and the 2nd season between 06/22/2015 and 07/23/2015. The application of PS increases by approximately 1/5 the cumulative emissions of carbon dioxide (CO2) into the atmosphere. Moisture and soil temperature influence and correlate positively with the emission of CO2 into the atmosphere C in soil with application of PS. In the first 24 hours after application of PS there is an increase in the CO2-C, CH4-C and N2O-N emission of approximately 156%, 14251% and 3076%, respectively, in relation to control. The application of PS in the dry season, accumulated emissions increases of CO2-C, compared with mineral fertilization. During the rainy season, there is an increase in emissions of CH4-C and N2O-N. The PAG and C equivalent duplicate when applying 90 m3 ha-1 of PS in the rainy season. However, when considering the accumulated biomass, there is a decrease of 12% from the C equivalent to 1 kg of C.