Shelterbelt influence on soil microbial carbon and phosphorus limitation in farmland: Implications for soil health

Soil microbial metabolism and nutrient limitation status are crucial for nutrient cycling and terrestrial ecosystem stability, yet they are not fully studied in farmland shelterbelt systems. In this study, we assumed that microbial nutrient limitation responses to soil nutrient dynamics in farmland are regulated by the distance from the shelterbelts and the presence of ditches. We measured the activities of carbon (C)-, nitrogen (N)-, and phosphorus (P)-acquiring enzymes, alongside soil total and available nutrient content, and microbial properties in farmland with shelterbelts in Northeast China. Results indicated that soil microbial communities were predominantly co-limited by C and P, with marked shifts towards increased nutrient limitation in the ditched conditions, especially near the shelterbelt area. These shifts correlate strongly with soil nutrient availability and its stoichiometry, suggesting that the balance of nutrient stoichiometry is pivotal in maintaining microbial metabolic stability and elemental homeostasis. Further insights from structural equation modeling and random forest analyses revealed that soil organic C, microbial biomass N, and bacterial phospholipid fatty acids were the key drivers of microbial C limitation. Available nutrients primarily influenced microbial P limitation, underscoring the complex interplay between soil management practices and the status of microbial nutrient limitation. The findings highlighted the optimized management, such as enhancing organic matter and available nutrients through practices like crop residue return and fertilization based on ditch presence and distance, could alleviate microbial nutrient limitation, maintaining soil health and sustain ecosystem sustainability in farmland shelterbelt systems.