Effects of Temporal Variation in Long-Term Cultivation on Organic Carbon Sequestration in Calcareous Soils: Nile Delta, Egypt

摘要: Soil carbon sequestration is a riskier long-term strategy for climate mitigation than direct emissions reduction, but it plays main role in closing emission gaps. Effects of cultivation on soil were studied at the western edge Nile Delta near Alexandria, Egypt. Seven agricultural fields different ages (0–50 years use) selected and compared with surrounding desert (virgin soil) shrub-land. Samples taken three horizons, 0–30, 30–60, 60–90 cm, tested differences physical chemical properties. The results reveal that European Commission (EC) value was 11.77 dS/m virgin soil, while EC values decreased to 5.82, 4.23, 3.74, 2.40, 2.26 after 5, 10, 20, 30, 50 cultivation, respectively. calcareous rock fraction smaller μm size revealed another phenomenon, where active calcium carbonate content increased practices from 1.15% 5.42%, 6.47%, 8.38%, 10.13% 30 respectively, shrub-land also showed low amount CaCO3 1.38%. In fifty bulk density significantly 1.67 1.11 g/cm3, 1.65, 1.44, 1.40, 1.25 g/cm3 years, These increase stock upper 90 cm amounted 41.02 t C/ha five 13.47 C/ha. levels steeply during an average rate 8.20 per year cm. After first slowed, reaching 4.68, 3.77, 2.58, 1.93 resulting sequestration-potential 46.78, 75.63, 77.43, 96.45 indicate potential resembles logarithmic curve until equilibrium state between application decomposition by microorganisms reached.