Nitrate leaching beneath a containerized nursery crop receiving trickle or overhead irrigation

Area of Science:

• Horticultural Science
• Environmental Science
• Soil Science

Background:

• Container nursery production is resource-intensive.
• Nitrogen release from nursery containers poses environmental risks.
• Optimizing irrigation is crucial for sustainable nursery management.

Purpose of the Study:

• To evaluate trickle irrigation as an alternative to overhead irrigation for reducing nitrogen (N) release in container nurseries.
• To compare the environmental impact of different irrigation methods on nitrate leaching.
• To assess the efficacy of trickle irrigation in mitigating nitrogen pollution from horticultural operations.

Main Methods:

• Investigated containerized rhododendron growth under overhead and trickle irrigation.
• Utilized soil-monolith lysimeters to collect leachate over two years.
• Measured leachate nitrate N concentration, flow-weighted concentration, and volume.
• Accounted for natural precipitation as a water input.

Main Results:

• Leachate nitrate N concentrations frequently exceeded the U.S. Environmental Protection Agency (USEPA) limit of 10 mg L(-1).
• Average annual nitrate N loss was higher with trickle irrigation (60.5 kg ha(-1)) than overhead irrigation (51.8 kg ha(-1)).
• Flow-weighted nitrate N concentration was greater with trickle irrigation (12.7 mg L(-1)) compared to overhead irrigation (7.2 mg L(-1)).

Conclusions:

• Trickle irrigation did not reduce nitrate N leaching in container nurseries under the study conditions.
• High precipitation significantly impacted water balance, diminishing the anticipated benefits of trickle irrigation.
• Environmental nitrogen release from container production requires further investigation beyond irrigation method alone.