[Study on regularity of greenhouse gas emissions from black soil with different reclamation years]

Regularity of greenhouse gas emissions from black soil with different reclamation years in northern China was investigated by an incubation experiment. Soil samples cultivated for 2 years, 30 years, 100 years and uncultivated were collected and incubated at 2 degrees C and a soil moisture of 60% of the water hold capacity (WHC) for 7 days. The results indicated that the physical and chemical properties of black soil changed significantly after reclamation, which had significant influence on the greenhouse gas emissions. N2O emission was stimulated after soil was reclaimed, the longer time of reclamation, the higher N2O emitted from soil, and the N2O emissions from soil cultivated for 30 and 100 years were significantly higher than that from uncultivated soil. There were significant positive correlations between N2O emission and the content of water organic nitrogen and silt in soil, whereas significant negative correlations were found between pH, sand content and N2O emission. CO2 emission decreased after the soil was cultivated, and CO2 emission from soil cultivated for 30 and 100 years were significantly lower than that of uncultivated soil. There were significant positive correlations between organic carbon, water organic carbon and CO2 emission. All of the soils behaved as weak sources of CH4 emission during the first 4 days of incubation, and then behaved as weak sink of atmospheric CH4, the CH4 cumulative emission increased with reclamation years. The difference of CO2 and CH4 emissions from black soil with different reclamation years may be attributed to the difference of soil pH, organic carbon, soluble organic carbon and the contents of sand and silt.