Denitrification losses from outdoor piglet production: spatial and temporal variability

Area of Science:

• Environmental Science
• Soil Science
• Animal Science

Background:

• Outdoor piglet production systems are increasing due to animal welfare concerns.
• These systems may lead to substantial nutrient losses, particularly nitrogen (N).
• Understanding nutrient cycling, specifically denitrification, is crucial for mitigating environmental impact.

Purpose of the Study:

• To investigate the spatial distribution and seasonal variation of denitrification activity in outdoor piglet production systems.
• To identify key factors influencing denitrification rates, including soil properties and management practices.
• To quantify overall nitrogen losses through denitrification in this production system.

Main Methods:

• Spatial mapping of denitrification rates using a 5x5m grid inside and outside paddocks post-sow removal.
• Seasonal monitoring of denitrification activity via soil cores along transects over one year.
• Statistical modeling incorporating soil parameters (dissolved organic carbon, inorganic N) and proximity to management features (feeders, huts).

Main Results:

• Denitrification rates were substantially higher within paddocks (0.1-0.5 kg N ha⁻¹ d⁻¹) compared to outside (0.01 kg N ha⁻¹ d⁻¹).
• Highest rates were observed near feeders, correlating with elevated soil dissolved organic carbon and inorganic nitrogen.
• Dissolved organic carbon significantly influenced denitrification under moist conditions; climate and management practices also played a role.

Conclusions:

• Outdoor piglet production systems exhibit significant nitrogen losses via denitrification, estimated at 69 kg N ha⁻¹ yr⁻¹ (11% of N surplus).
• Management practices, particularly feeder placement, and soil conditions strongly influence denitrification hotspots.
• Mitigation strategies should focus on managing nutrient hotspots within paddocks to reduce nitrogen pollution.