Figures & data
Figure 1 Location of six soil sampling sites: 100-year farmland (100), 80-year farmland (80), 30-year farmland (30), 15-year farmland (15), 10-year farmland (10) and natural land (0).
Figure 2 Depth distribution of (a) soil organic carbon (SOC) concentration, (b) total nitrogen (TN) concentration, (c) carbon:nitrogen (C:N) ratio and (d) bulk density in different cultivated farmlands. Corresponding data for 10- and 80-year farmlands were similar to these of 15- and 100-year farmlands, respectively, and they are not displayed in the line charts in order to display the SOC and TN dynamics clearly. Bars show the standard errors of means.
Figure 3 Changes of (a) soil organic carbon and (b) total nitrogen stocks at different depths after conversion of desert soil to irrigation farmlands. Different letters for each depth interval indicate significant differences between farmlands cultivated in different years (P < 0.05). Bars show the standard errors of means.
Table 1 Basic conditions of the sample plots