Microsite Determines the Soil Nitrogen and Carbon Mineralization in Response to Nitrogen Addition in a Temperate Desert

oleh: Yingwu Chen, Haorui Li, Huilu Sun, Yuxin Guo

Format: Article
Diterbitkan: MDPI AG 2023-06-01

Deskripsi

Nitrogen deposition can change the soil in N and C cycling processes. However, a general understanding of how N deposition changes C and N mineralization has not yet been reached. Soil organic C and N mineralization beneath the dominant shrubs of <i>Haloxylon ammodendron</i> and between the shrubs in response to two levels of N addition (2.5 gN m<sup>−2</sup> and 5 gN m<sup>−2</sup> per year) were investigated in the 1st, 4th, and 9th year of N addition in a temperate desert of northern China. N addition promoted soil N mineralization (R<sub>m</sub>N), and the nitrification rate (R<sub>NN</sub>) increased C mineralization in the interplant and decreased it beneath shrubs. N addition increased soil microbial biomass C (C<sub>mic</sub>), N (N<sub>mic</sub>), and PLFAs in the interplant, and decreased it beneath shrubs. R<sub>m</sub>N and R<sub>NN</sub> were related to N<sub>mic</sub>, and R<sub>CM</sub> was related to C<sub>mic</sub> and the total PLFAs. N addition increased the fungal biomass alongside the ratio of fungal to bacterial PLFAs in the interplants while decreasing them beneath shrubs. Our results support how N addition can increase soil N mineralization and nitrification, but the effects on soil C mineralization are dependent on the amount of nitrogen addition, the soil’s available carbon content, and water. Finally, the divergent responses of microbial communities to N addition between microsites suggest that the “fertile islands” effects on nutrients and microbial biomass are important when estimating feedbacks of C and N cycling to projected N deposition in the desert ecosystem.