氮磷添加对草甸草原土壤氮磷转化功能基因丰度的影响

氮添加是提高退化草地生产力的主要养分管理措施，而过量的氮输入会导致土壤酸化、增加硝酸盐淋溶损失和温室气体排放。旨在明确草原割草利用下土壤氮、磷转化功能基因丰度对氮磷添加的响应规律，为定向调控打草场土壤氮、磷转化过程，提高养分利用效率，减少温室气体N₂O排放提供科学依据。2018—2020年在呼伦贝尔草甸草原打草场设置了5个施氮水平(0、1.55、4.65、13.95、27.9 g N m^-2 a^-1)和3个磷水平(0、5.24、10.48 g P m^-2 a^-1),裂区试验设计，在植物不同生长时期测定土壤氨氧化(amoA-AOA和amoA-AOB)、反硝化(narG、nirK、nirS和nosZ)和磷转化(phoD)基因丰度。结果表明，土壤氮转化基因丰度受到氮、磷添加的调控，而氮、磷添加对土壤磷转化功能基因丰度无显著影响(P>0.05)。氮添加可提高amoA-AOB基因丰度，增加氨氧化细菌调控土壤总硝化速率的相对重要性，因此能增加硝酸盐淋溶损失潜势。高氮处理下添加磷可降低...

Responses of soil nitrogen and phosphorus transformation functional genes abundances to nitrogen and/or phosphorus additions in a meadow steppe

Nitrogen (N) addition is a primary nutrient management practice to improve the productivity of degraded grasslands. Excessive N input leads to soil acidification, the increase of nitrate leaching loss and greenhouse gas emissions. This study aims to understand the response characteristics of the abundances of soil N and phosphorus (P) transformation functional genes to nitrogen and phosphorus additions, and provide reference for directionally regulating the transformation process of soil nitrogen and phosphorus, improving nutrient utilization efficiency, and reducing greenhouse gas N₂O emissions in grassland which is used mostly for haymaking. We conducted a spit-plot experiment of nutrient additions that included five N levels (0, 1.55, 4.65, 13.95, 27.9 g N m^-2 a^-1) and three P levels (0, 5.24, 10.48 g P m^-2 a^-1) and their interactions in Hulunber meadow steppe for three years (2018-2020). The abundance of genes involved in soil ammonium oxidation (amoA-AOA and amoA-AOB), denitrification (narG, nirK, nirS and nosZ) and organophosphate transformation (phoD) processes at different growth stages of plants were determined. The abundances of soil N-cycle genes were regulated by N and P additions, while the abundances of soil organophosphate transformation gene maintained constant in response to N and P additions. N addition increased the abundance of amoA-AOB and increased the relative importance of ammonia oxidizing bacteria in regulating soil nitrification rate, resulting in increasing the potential of nitrate leaching loss. P addition reduced the abundance of amoA-AOB under high N treatments, thereby decreased the potential of nitrate leaching loss. The abundance of denitrification genes (nirK and nosZ) in response to N addition varied with plant growth seasons. N addition significantly promoted the abundance of nirK and nosZ in August, thereby increasing gaseous N loss potential. Excessive N input might promote the process of soil ammonia oxidation and denitrification, and increase the potential of nitrate leaching loss and gaseous N loss. P addition may reduce the potential of nitrate leaching loss and play a potential role in improving N utilization efficiency.