Linkages of Nitrogen-Cycling Microbial Resistance and Resilience to Soil Nutrient Stoichiometry Under Dry-Rewetting Cycles with Different Fertilizations and Temperatures in a Vegetable Field

Multiple dry-rewetting (DRW) cycles occur in intensively managed vegetable fields due to frequent tillage and irrigation. Soil nitrogen (N) cycling depends on the resistance and resilience of related microbial populations to DRW cycles, which could be closely related to soil nutrient status. However, the linkage of N-cycling microbial resistance and resilience and soil nutrient stoichiometry remains unknown in vegetable field. Here, we established four fertilization treatments in a four-year greenhouse vegetable field: no N fertilization (CK), chemical N fertilization (CN), substituting 50% of chemical N with organic fertilizer (1M1N) or biofertilizer (1BM1N). Then, we set up an 85-day DRW-cycling incubation compared with constant moisture at 15, 25 and 35 ℃. The results showed that the resistance indices of N-cycling microbes ranged from 0.87 to 0.99, while the resilience indices ranged from -0.36 to 0.76. Microbial resistance was significantly higher, while microbial resilience was significantly lower in the 1M1N treatment than in the CN treatment. There was no significant difference in microbial resistance and resilience between the CN and 1BM1N treatments. The N-cycling microbes showed slightly higher resistance but lower resilience at 15 ℃ than at 25 and 35 ℃. Thus, N-cycling microbes showed an important trade-off between their resistance and resilience to DRW cycles. Furthermore, most treatments showed microbial carbon limitation and N abundance during DRW cycles and recovered gradually to the undisturbed state. Microbial resistance was significantly related to the soil nutrient stoichiometry of carbon, N and phosphorus, while microbial resilience was mainly correlated with carbon-related indicators. In conclusion, N-cycling microbes presented good stability to frequent DRW cycles, which was linked to not only the classic "historical legacy effects" but also soil nutrient stoichiometry in the vegetable field.