| 英文摘要： |
Soil organic carbon (SOC) is a critical mass of global terrestrial carbon store that can be altered by land use and land management practices. As an important grain production area in the Yellow River basin, there have been intensive agricultural activities in the Guanzhong Plain for over 1000 years. The conversion of cropland into orchard and changes in land management practices could have altered the distribution and amount of SOC stores in the region. To determine spatial variations in SOC and its response to changes in land use and land management practices in the thousand-year cultivated region, SOC content was measured at 127 sites, including 117 sites in the 0-100 cm soil layer and 10 sites in the 0-1000 cm soil layer. The results showed a pronounced decline in SOC content with increasing depth in the upper 100 cm soil layer, whereas it was relatively low and stable in deeper soil layers. SOC stock in the 0-100 and 100-1000 cm soil layers accounted for 16.9% and 83.1%, respectively, of the total SOC stock in the 0-1000 cm soil profile. Compared with the 1980s, mean SOC stock in the 0-100 cm soil layer significantly increased (by 0.69 kg m-2) over the 40-year period. Furthermore, no significant difference was observed in SOC content between cropland and orchard land soils for both the 0-100 and 100-1000 cm soil layers. Land management practices (irrigation and fertilization), climatic variables (precipitation and temperature), and soil properties (pH and clay content) together influenced the spatial variations in SOC in the 0-60 cm soil depth. However, variations were dominantly driven by soil properties at depths below 60 cm. Therefore, while SOC in layers below 100 cm was critical for carbon budget estimations, SOC was not altered by changes in agricultural land use in both the shallow and deep soils of the study area. Agricultural management practices, soil properties, and organic carbon storage in deep soils need to be considered in future carbon budget studies in cultivated lands, especially in regions with deep soils. |
在线留言
联系我们
所长信箱