Figure 5.

Effects of water and nitrogen regulation on soil carbon fractions. Note: Different lowercase letters indicate that there is a significant difference between different nitrogen application rates under the same irrigation amount, and different uppercase letters indicate that there is a significant difference between different irrigation amounts (p < 0.05). In the analysis of variance, * and ** indicated that the correlation reached a significant level (p < 0.05) and a very significant level (p < 0.01), respectively, and ns indicated that the correlation was not significant (p > 0.05).