CO2 emissions in calcareous soil under various manure additions and water availability levels

Document Type: Original Article


1 Agricultural Research Directorate, Ministry of Science and Technology, Baghdad, Iraq

2 Department of Soil Sciences and Water Resources, University of Diyala, Iraq


Carbon mineralization is the phenomenon where organic carbon forms are converted to carbon dioxide (CO2) which is then released to the surrounding environment. Many factors can affect carbon mineralization such as drought conditions and organic material compositing stage. This experiment aims to investigate the effect of different manure application levels in addition to different water availability levels on CO2 mineralization in calcareous soil over time. For this purpose, different mixed manure inputs of (0%, 5%, and 10%) were added to airily dried calcareous soil samples and different water availability levels (40%, 50%, and 60%) were applied. CO2 emissions were then monitored during an incubation period of 65 days 30 ±2 C.The results showed that by increasing organic matter input, CO2 fluxes were increased during the incubation period to reach 198.55 mg/100g soil in 10% organic matter treatments after 50 days of incubation. Water availability appeared to have little to no influence over CO2 emissions within the chosen experimental ranges. Furthermore, response surface model contours and fitted means factorial interaction plots of CO2 emissions showed that the added organic matter underwent a severe mineralization activity since the first day of incubation. These results refer to the high carbon mineralization rates in calcareous soils under dry conditions, and the increased CO2 emissions by increasing manure inputs refer to the importance of using more stable composted material rather than higher organic material inputs in this type of soil.


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