Nitrogen Application Under Integrated Water-Fertilizer Management Regulates Rhizosphere Nitrogen Dynamics, Microbial...

Area of Science:

• Agricultural Science
• Soil Science
• Microbiology

Background:

• Nitrogen management is crucial for maize productivity in fertigation systems.
• Understanding nitrogen's impact on rhizosphere processes and microbial stability is essential.

Purpose of the Study:

• To investigate how varying nitrogen inputs affect rhizosphere nitrogen dynamics, microbial community assembly, and maize yield.
• To clarify the mechanisms linking nitrogen application gradients to microbial community stability and nitrogen transformations.

Main Methods:

• Field experiment with four nitrogen levels (0, 100, 140, 180 kg·hm⁻²).
• Analysis of rhizosphere nitrogen forms (nitrate-N, DON) across key growth stages.
• Assessment of microbial community composition, core/transient taxa, network analysis, and functional predictions.
• Maize grain yield measurement.

Main Results:

• Moderate nitrogen (140 kg·hm⁻²) significantly increased soil nitrate-N and dissolved organic nitrogen (DON), enhancing maize yield by 25.7%.
• Excessive nitrogen (180 kg·hm⁻²) did not further improve nitrogen fractions and potentially reduced nitrogen-use efficiency.
• Nitrogen application altered microbial community structure, reduced chemoheterotrophy and nitrogen-cycling functions, but decreased pathogenic fungi.
• Bacterial networks became more cohesive, while fungal networks showed reduced connectivity.

Conclusions:

• Moderate nitrogen fertilization optimizes rhizosphere nitrogen availability and maize productivity in semi-arid fertigation systems.
• Nitrogen management influences soil microbial community structure, function, and ecological interactions.
• Findings provide insights into microbiological responses to nitrogen application for sustainable agriculture.