A least-input nitrogen fertilizer reduction strategy sustains peanut yield with lower nitrogen inputs

Area of Science:

• Agricultural Science
• Nanotechnology
• Environmental Science

Background:

• Synthetic nitrogen fertilizers are crucial for food security but cause environmental issues like GHG emissions and soil degradation.
• Reducing nitrogen fertilizer use often leads to decreased crop yields and farmer income, presenting a significant challenge.
• Nanotechnology offers potential solutions to improve nitrogen use efficiency and decouple crop yield from fertilizer dependency.

Purpose of the Study:

• To develop a low-input foliar fertilization strategy using bio-derived nanocarbon (BNC) for peanut (Arachis hypogaea L.).
• To achieve a 30% reduction in synthetic nitrogen (N) input without sacrificing crop yield, nutritional quality, or economic returns.
• To elucidate the physiological and microbiological mechanisms underlying this strategy.

Main Methods:

• Field trials were conducted with peanut over two growing seasons using four treatments: conventional N, reduced N (N-30), N + BNC, and N-30 + BNC.
• Assessed photosynthetic parameters, oxidative stress markers, and 15N isotope tracing.
• Utilized transcriptomic, metabolomic, and 16S rRNA microbiome analyses, alongside GHG emissions modeling (DNDC) and economic analysis.

Main Results:

• Applying BNC with 30% reduced N maintained crop yield by enhancing photosynthetic electron transport and reducing oxidative stress.
• BNC application upregulated HY5, activating nitrate and ammonium transporters, leading to increased 15N uptake and improved root nitrogen content.
• Nitrogen use efficiency (NUE) increased by 16.0%, GHG emissions decreased by 34.8%, and net profit rose by 27.0%.

Conclusions:

• Micro-dosage of upcycled BNC effectively reduces synthetic N input by orchestrating HY5-mediated signaling and restructuring the rhizosphere microbiome.
• This strategy sustains crop productivity, offering a commercially viable, low-input framework for climate-smart agriculture.
• The approach reconciles food security needs with environmental sustainability goals.