دانلود گزارش کارورزی و کار آموزی

چکیده : 

Upland soils have been identified as a major CO2source induced by human activities, such as fertilizerapplications. The aim of this study is to identify the characteristics of soil CO2emission and carbon bal-ance in cropland ecosystems after continuous fertilizer applications over decades. The measurementsof soil surface CO2fluxes throughout the years of 2009 and 2010 were carried out based on a fertiliza-tion experiment (from 1990) in a double cropping system rotated with winter wheat (Triticum aestivumL.) and maize (Zea mays L.) in upland soil in southern China. Four treatments were chosen from theexperiment for this study: no-fertilizer application (SR), nitrogen–phosphorus–potassium chemical fer-tilizers (NPK), NPK plus pig manure (NPKM) and pig manure alone (M). Results showed that the meanvalue of soil CO2fluxes from 08:00 to 10:00 am could represent its daily mean value in summer period(June–August) and that from 09:00 am to 12:00 pm for the rest season of a year. Soil temperature andmoisture combined together could explain 70–83% of variations of CO2emission. Annual cumulativesoil CO2fluxes in the treatments with manure applications (8.2 ± 0.8 and 11.0 ± 1.2 t C ha−1in 2009, and7.9 ± 0.9 and 11.1 ± 1.2 t C ha−1in 2010 in NPKM and M, respectively) were significantly higher than thosein the treatments with non-manure addition (2.5 ± 0.2 and 3.4 ± 0.2 t C ha−1in 2009, and 2.1 ± 0.2 and3.7 ± 0.3 t C ha−1in 2010 in SR and NPK, respectively). However, the treatments with manure applicationsrepresented a carbon sink in the soil (carbon output/input ratio < 1.0), which demonstrated potential forcarbon sequestration.