Nutrient balance regulates soil microbial health under long-term fertilization

Area of Science:

• Agricultural Science
• Soil Microbiology
• Environmental Science

Background:

• Fertilizer application is crucial in intensive agriculture, significantly impacting soil microbial communities.
• The long-term effects of different nutrient inputs on microbial eco-evolutionary strategies and functions remain poorly understood.

Purpose of the Study:

• To investigate how 180 years of distinct fertilization regimes influence soil microbial communities, their ecological functions, and eco-evolutionary dynamics.
• To elucidate the mechanisms behind microbial responses to inorganic versus organic nutrient supplies.

Main Methods:

• Utilized a 180-year-old field fertilization experiment.
• Conducted microbial culturing and pot experiments.
• Performed comprehensive metagenomic data analysis to assess microbial community structure, function, and antibiotic resistance genes (ARGs).

Main Results:

• Exclusive inorganic fertilization led to carbon-nitrogen imbalances, intensifying microbial resource competition and elevating antibiotic resistance gene (ARG) levels.
• Viruses amplified ARG spread via a "piggyback the winner" strategy.
• Imbalanced nitrogen from chemical fertilizers disrupted ecological niches, increasing virulent viruses and reducing microbial nutrient cycling capacity.
• Balanced organic fertilization decreased microbial competition and enhanced microbial growth.

Conclusions:

• Long-term inorganic fertilization negatively impacts soil microbial health and function, increasing antibiotic resistance.
• Organic fertilization promotes a healthier soil microbiome and nutrient cycling.
• Sustainable agriculture requires careful management of soil nutrient conditions and responsible antibiotic use in livestock.