DOI:https://doi.org/10.1016/j.jenvman.2025.126349
发表期刊：Journal of Environmental Management
链接：https://www.sciencedirect.com/science/article/pii/S0301479725023254
作者：Fei Yan1, Qian Huang1, Dongming Chen, Xin Zheng, Rui Yin, Kangqi Zhang, Yan Lu, Yanfu Bai, Feida Sun, Jiqiong Zhou, Zhouwen Ma, Geng Sun, Christopher W.N. Anderson, Ran Xue*, Lin Liu*
Abstract:Organic acids can enhance inorganic nitrogen transformation in rhizosphere soil, however the specific influence of long-chain organic acids on thecommunity and functional structureof soilmicroorganismsthat control nitrogen cycling is poorly understood.Organic acids have shown potential to increase the resilience of alpineecosystems against desertification. To address this knowledge gap, we conducted a controlled experiment in a microcosm rhizosphere system.Using artificial roots (7.85 cm² surface area), we amended Qinghai-Tibet Plateau soil with palmitic acid for 45 days at three secretion rates (½×, 1×, and 2× thein siturate of 3.20 μg C d⁻¹ cm⁻²), corresponding to 12.56, 25.12, and 50.24 μg C d⁻¹ root⁻¹ respectively, with a control group receiving only osmoregulation solution.The results revealed a remarkable 81% increase in soil NH4+-N concentrationat the highest addition rate of palmitic acid. Moreover,bothmicrobial biomass and the abundance of nitrogen-fixing genesnifK(12.25 times),nifH(7.63 times), andnifD(27.33 times) increasedsignificantly, alongside a substantial rise in therelativeabundance ofAzospirillum(12.9-fold). Notably, 82% of biomarkers in the high-rate palmitic acid treatment were linked to nitrogen fixation. The structural equation model indicated a direct impact of nitrogen fixation on NH4+-N concentration. Our findings suggest that palmitic acid primarily enhances microbial biomass and drives nitrogen fixation processes through its decline to pH, rather than serving as a direct carbon source.Consequently, within the range of our experimental setup,the preferential selection of plant specieswith a highroot exudationrate ofpalmitic acid can optimize NH₄⁺-N retention in rhizosphere soil, thereby promoting plant growth and facilitating vegetation restorationacross the desertification alpine grasslands in the Qinghai-Tibet Plateau.
Keywords:root exudate,nitrogen cycle, alpine grassland, microbial functional taxa, desertification
