Soil denitrification stimulated by macroplastics in maize cultivation

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Macroplastics (> 2 cm) are an emerging pollutant in agricultural soils.
• Their impact on nitrogen (N) cycling and crop performance, particularly in maize cultivation, is poorly understood.
• Maize-based intercropping systems are widely promoted globally.

Purpose of the Study:

• To investigate the effects of macroplastics on soil-plant nitrogen dynamics in maize-soybean intercropping systems.
• To assess the impact of macroplastics on maize growth, root development, and yield.
• To analyze microbial-mediated nitrogen transformations under macroplastic contamination.

Main Methods:

• Mesocosm and field experiments were conducted.
• Macroplastic treatments were applied to maize-soybean intercropping systems.
• Soil nitrogen concentrations, plant growth parameters, and microbial N-transforming activities were measured.

Main Results:

• Macroplastics had minimal impact on aboveground maize morphology and yield but significantly inhibited root development.
• Soil nitrate-nitrogen concentrations decreased, while nitrite reductase activity and 15N retention increased, indicating reduced N uptake by maize.
• Abundance of denitrifying bacteria and genes increased, suggesting a higher potential for nitrogen loss via denitrification.

Conclusions:

• Macroplastic exposure in intercropped maize systems does not significantly alter aboveground growth but impairs root development and nitrogen uptake.
• Contamination leads to soil conditions favoring nitrogen loss through denitrification.
• Managing denitrification is crucial for improving nitrogen use efficiency and crop yields in macroplastic-polluted agricultural soils.