Agricultural ecosystems rather than fertilization strategies drives structure and composition of the ureolytic microbial functional guilds.

Abstract

Ureolytic microorganisms are significant in the transformation of soil nitrogen as they secrete urease to hydrolyze urea. This study aimed to investigate the effects of different fertilization regimes on ureolytic microbial functional guilds (bacteria, fungi, and archaea) in various agricultural ecosystems. Soil samples were collected from a long-term agricultural field experiment involving paddy and dryland soils. The experiment consisted of four fertilization treatments: nitrogen fertilizer (N), nitrogen fertilizer combined with composite urease/nitrification inhibitor (NI), nitrogen fertilizer combined with straw (NS), and nitrogen fertilizer combined with manure (NO). A metagenomic sequencing technique was used to assess the composition of ureolytic microbial functional guilds using the target ureC gene, along with the evaluation of soil physicochemical properties, the abundance of ureC genes from different microbial guilds, and the urease activity. The results showed that the NI treatment significantly increased the abundance of ureC genes from different microbial guilds in the two agricultural ecosystems compared with other fertilization treatments. In dryland soil, the abundance of ureC genes was positively correlated with urease activity. The ureolytic bacterial functional guild exhibits greater dominance at all taxonomic levels compared to the ureolytic fungal and archaeal functional guilds. The alpha diversity of ureolytic microbial functional guilds was greater in dryland soil than in paddy soil. Principal coordinate analysis showed that the structure of the ureolytic microbial functional guilds could be separated into two groups based on agricultural ecosystems. Phosphorus is a key environmental factor affecting the ureolytic microbial functional guilds in two agricultural ecosystems, and the structure of the ureolytic bacteria functional guild is more susceptible to pH. The results suggest that the structure of ureolytic microbial functional guilds is primarily determined by agricultural ecosystems rather than by fertilization treatments. Additionally, fertilization treatments across different agricultural ecosystems significantly impacted the community composition of ureolytic bacteria, fungi, and archaea microorganism.