Biochar effects on crop yields and nitrogen loss depending on fertilization

Area of Science:

• Soil Science
• Agronomy
• Environmental Science

Background:

• Biochar (BC) application to low-fertility soils offers potential for enhanced crop yield, soil quality, and climate change mitigation.
• Limited field studies exist on the combined impacts of biochar and nitrogen (N) fertilization on crop productivity and N losses.

Purpose of the Study:

• To investigate the combined effects of two biochar rates and five nitrogen fertilization rates on crop productivity and nitrogen losses.
• To evaluate these effects within a long-term winter wheat/summer maize rotation system in the North China Plain.

Main Methods:

• A long-term field experiment initiated in 2008.
• Application of two biochar rates and five nitrogen fertilization rates.
• Monitoring of crop yields, N2O fluxes, NH3 volatilization, and soil mineral N content.

Main Results:

• Crop yields showed a linear-plateau response to N rates; BC effects on yield were negligible.
• BC retained mineral N (240 kg N ha⁻¹ yr⁻¹), increased NH3 volatilization (31% in wheat, 26% in maize) due to pH rise.
• BC reduced N2O emissions at lower N rates but stimulated them at higher N rates in the maize season.

Conclusions:

• Biochar application can improve nitrogen retention but increases ammonia volatilization.
• The impact of biochar on N2O emissions is dependent on nitrogen fertilization levels and crop type.
• Optimizing biochar and nitrogen rates is crucial for sustainable agricultural management in wheat/maize rotations.