Emission of carbon dioxide influenced by nitrogen and water levels from soil incubated straw

Abstract

An incubation study was carried out to investigate the influence of nitrogen rates to determine optimum C/N ratio under various moisture levels for straw decomposition and sequester carbon (C) in the soil. The aim was to observe straw carbon mineralization through measuring the amount of CO2 evolution. A clay loam topsoil mixed with maize straw was supplied with four nitrogen rates (0.04, 0.08, 0.16, 0.32 g N/kg) using (NH4)2SO4 to adjust C/N ratios at 82, 42, 20, and 10. Soil moisture was maintained at 55%, 70%, 85%, and 100% of field capacity incubated at 25°C for 53 days. The experiment was set up with 16 treatments arranged in complete randomized design. Results showed that mixing of straw with soil increased 50% cumulative CO2-C compared to controls. Averagely, about 44% of added maize straw C was mineralized to CO2-C. Straw addition along with nitrogen and moisture had significant relationships (P < 0.05) to cumulative CO2-C, soil organic C and microbial biomass C. There was a highly significant relationship (R2 = 0.99) between CO2-C emission and incubation time.