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Using RZWQM2-P to capture tile drainage phosphorus dynamics in Ohio
Harmanpreet Singh Grewal1, Zhiming Qi1, Vinayak Shedekar2
1Department of Bioresource Engineering, McGill University, Sainte-Anne-De-Bellevue, Québec, Canada.
Journal of Environmental Quality
|November 26, 2024
Summary
This study validates the RZWQM2-P model for simulating phosphorus loss in tile-drained fields. Results show winter cover crops reduce phosphorus loss, while controlled drainage may increase it, highlighting RZWQM2-P
Area of Science:
- Environmental Science
- Agricultural Science
- Water Quality Management
Background:
- Phosphorus (P) loading from agricultural lands with tile drainage contributes to water quality degradation and ecosystem damage.
- The RZWQM2-P model simulates P fate and transport in soil-water-plant systems, particularly in tile-drained croplands.
- Limited comprehensive evaluation of the RZWQM2-P model hinders its application in P management.
Purpose of the Study:
- To evaluate the RZWQM2-P model's accuracy in simulating phosphorus dynamics in tile-drained agricultural systems.
- To assess the effectiveness of management practices, specifically controlled drainage (CD) and winter cover crops (CC), in mitigating P losses.
- To provide a validated tool for optimizing P management strategies in agricultural settings.
Main Methods:
- Calibrated and validated the RZWQM2-P model using extensive field data on water flow and P loss (dissolved reactive P and total P) from a tile-drained site in Ohio (2017-2020).
- Monitored subsurface drainage and surface runoff flows on a daily basis.
- Utilized the validated model to simulate the impact of controlled drainage and winter cover crops on P loss compared to a base scenario and free drainage.
Main Results:
- The RZWQM2-P model satisfactorily simulated daily and monthly dissolved reactive P (DRP) loss and monthly total P (TP) loss, with Nash-Sutcliffe efficiency (NSE) values ranging from 0.50 to 0.73.
- Daily TP simulation accuracy was lower (NSE = 0.30).
- Simulations indicated winter rye cover crops reduced DRP by 16% and TP by 4%, while controlled drainage increased DRP (60%-129%) and TP (5%-17%) losses at tested elevations.
Conclusions:
- The RZWQM2-P model effectively captures phosphorus dynamics in tile-drained croplands, proving to be a valuable tool for P management.
- Winter cover crops show potential for reducing P losses from agricultural drainage systems.
- Controlled drainage, depending on outlet elevation, may increase P losses, necessitating careful implementation.
