Influence of carbonized crop residue on soil carbon storage in red pepper field

Background: Because of climate change, interest in the development of carbon pools has increased. In agricultural ecosystems, which can be more intensively managed than forests, measures to control carbon dioxide (CO2) emission and absorption levels can be applied relatively easily. However, crop residues may be released into the atmosphere by decomposition or combustion. If we can develop scientific management techniques that enable these residues to be stocked on farmland, then it would be possible to convert farmlands from carbon emission sources to carbon pools. We analyzed and investigated soil respiration (Rs) rate characteristics according to input of carbonized residue of red peppers (Capsicum annuum L.), a widely grown crop in Korea, as a technique for increasing farmland carbon stock. Results: Rs rate in the carbonized biomass (CB) section was 226.7 mg CO2 m−² h−¹ , which was 18.1% lower than the 276.9 mg CO2 m−² h−¹ from the red pepper residue biomass (RB) section. The Rs rate of the control was 184.1 mg CO2 m−² h−¹ . In the following year, Rs in the CB section was 204.0 mg CO2 m−² h−¹ , which was 38.2% lower than the 330. 1 mg CO2 m−² h−¹ from the RB section; the control emitted 198.6 mg CO2 m−² h−¹ . Correlation between Rs and soil temperature ((Ts) at a depth of 5 cm) was R2 = 0.51 in the RB section, which was higher than the other experimental sections. A comparison of annual decomposition rates between RB and CB showed a large difference, 41.4 and 9.7%, respectively. The results showed that carbonization of red pepper residues reduced the rates of decomposition and Rs. Conclusions: The present study confirmed that the Rs rate can be reduced by carbonization of residue biomass and putting it in the soil and that the Rs rate and Ts (5 cm) were positively correlated. Based on the results, it was determined that approximately 1.2 t C ha−¹ were sequestered in the soil in the first year and 3.0 t C ha−¹ were stored the following year. Therefore, approximately 1.5 t C ha−¹ year−¹ are expected to be stocked in the soil, making it possible to develop farmlands into carbon pools.