Effect of type and quality of two contrasting plant residues on CO2 emission potential of Ultisol soil: Implications for indirect influence of temperature and moisture

• Amendments e.g. addition of plant residues are major CO2 emission governing factors.
• Residues with low decomposition can be successfully used to control CO2 emission.
• Residues with slow decomposition convert the soils from CO2-C sources to sinks.
• Other abiotic factors e.g. temperature and moisture are indirect regulator of CO2.

The emission of CO2 from soil to the atmosphere is a major challenge throughout the world in both developed and developing countries, due to its critical role in the intensification of global warming. An incubation experiment was conducted to investigate CO2 emission potentials of Ultisol soils under residues of peanut (green manure) and rice (rice straw) and moisture regimes 60% (W1) and 120% (W2) of water holding capacity at different temperature ranges i.e. low to medium 5–20 °C (T1 to T4), medium to high 25–30 °C (T5 to T6) and very high 35–45 °C (T7 to T9). Comparing two contrasting plant residues, we found that the incorporation of GM (green manure) residue significantly (P < 0.05) increased the CO2 emission potential of Ultisol soils at both moisture regimes and all temperature ranges, and this increase tended to improve with the increase of temperature ranges. Conversely, RS residue mixed treatments showed significantly low production and emission of CO2, at all temperature ranges and both water regimes. This indicated that type and quality of plant residues have significant impact on the CO2 production and emission capacity of soils and plant residues with low decomposition, high stability and high lignin, cellulose and hemicelluloses compounds can be successfully used as an organic amendment to control the emission and production of CO2 from soil to atmosphere, by converting soils from CO2–C sources to sinks. We revealed that moisture and temperature also had a significant (P < 0.05) effect on the CO2 production and emission potential of Ultisol soils, but this effect was indirect through influencing the rate of decomposition of the organic inputs. Our results suggested that applied amendments e.g. addition or incorporation of plant residues are in fact major factors which control the CO2 emission potential of soils by converting soils from CO2–C sources to sinks. On the other hand, other abiotic factors like temperature and moisture are indirect regulator of CO2 production and emission by influencing decomposition of these incorporated organic inputs.