Modeling and mitigating phosphorus losses in a tile-drained and manured field using RZWQM2-P

Authors: SADHUKHAN, DEBASIS - McGill University - Canada; QI, ZHIMING - McGill University - Canada; ZHANG, TIEQUAN - Agriculture And Agri-Food Canada; TAN, CHIN - Agriculture And Agri-Food Canada; Ma, Liwang

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2019
Publication Date: 6/13/2019
Citation: Sadhukhan, D., Qi, Z., Zhang, T., Tan, C., Ma, L. 2019. Modeling and mitigating phosphorus losses in a tile-drained and manured field using RZWQM2-P. Journal of Environmental Quality. 48:995-1005. https://doi.org/10.2134/jeq2018.12.0424.
DOI: https://doi.org/10.2134/jeq2018.12.0424

Interpretive Summary: Prediction of phosphorus (P) losses from surface runoff and tile drainage is necessary to understand widespread eutrophication. The objectives of this study were 1) to assess the accuracy of the newly RZWQM2-P (Root Zone Water Quality Model 2-Phosphorus) model in simulating phosphorus losses in surface runoff and tile drainage from manure amended field; and 2) to identify best management practices including water table control, manure application timing and methods to mitigate manure P losses using the calibrated model. The model was evaluated against data collected from a liquid cattle manure applied field with corn-soybean rotation in southwestern Ontario, Canada. The results demonstrated that the RZWQM2-P model satisfactorily simulated P losses in surface runoff and tile drainage. Compared to conventional management practices, manure injection reduced the P losses by 17.66% whereas controlled drainage and winter manure application increased P load by 12.95% and 22.59%, respectively. The study concluded that RZWQM2-P is a promising tool for P management in manure applied subsurface drained field and the injection of manure rather than controlled drainage is an effective P management practice to mitigate its losses from a subsurface drained field.

Technical Abstract: Prediction of phosphorus (P) losses from manure applied agricultural fields through surface runoff and tile drainage is necessary to mitigate widespread eutrophication. However, present water quality models do not have the capability to predict P losses particularly in tile drained and manure applied cropland. We developed a field scale P management model RZWQM2-P whose accuracy in simulating P losses from manure applied agricultural field is yet to be tested. The objectives of this study were 1) to assess the accuracy of this new model in simulating dissolved reactive phosphorus (Pdr) and particulate phosphorus (Ppart) losses in surface runoff and tile drainage from manure amended field; and 2) to identify best management practices including water table control, manure application timing and methods to mitigate manure P losses using the model. The model was evaluated against the data collected from a liquid cattle manure applied field with corn-soybean rotation in southwestern Ontario, Canada. The results revealed that the RZWQM2-P model satisfactorily simulated Pdr and Ppart losses through both surface runoff and tile drainage (NSE > 0.50, PBAIS within ± 25% and IoA > 0.75). Compared to conventional management practices, manure injection reduced the P losses by 17.66% whereas controlled drainage and winter manure application increased P load by 12.95% and 22.59%, respectively. The study concluded that RZWQM2-P is a promising tool for P management in manure applied subsurface drained field and the injection of manure rather than controlled drainage is an effective management practice to mitigate P losses from a subsurface drained field.