Winter rye cover crop impacts on runoff water quality in a northern New York (USA) tile-drained maize agroecosystem

Authors: GRIFFITH, KEEGAN - WILLIAM H. MINER AGRICULTURAL RESEARCH INSTITUTE; Young, Eric; KLAIBER, LAURA - WILLIAM H. MINER AGRICULTURAL RESEARCH INSTITUTE; KRAMER, STEPHEN - WILLIAM H. MINER AGRICULTURAL RESEARCH INSTITUTE

Submitted to: Journal of Water Air and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2020
Publication Date: 2/13/2020
Citation: Griffith, K.E., Young, E.O., Klaiber, L.B., Kramer, S.R. 2020. Winter rye cover crop impacts on runoff water quality in a northern New York (USA) tile-drained maize agroecosystem. Journal of Water Air and Soil Pollution. 231:84. https://doi.org/10.1007/s11270-020-4443-z.
DOI: https://doi.org/10.1007/s11270-020-4443-z

Interpretive Summary: Growing cover crops as part of maize silage production systems may help mitigate nutrient losses in surface runoff (SR) and tile drainage (TD). Relatively little research has quantified water quality impacts of cover crops on both SR and TD runoff. A better understanding of potential water quality impacts of growing a winter rye cover crop after maize silage harvest compared to the routine practice of leaving fields bare in the fall is needed to improve nutrient efficiency of maize systems. Four plots at the Miner Institute in northern New York, USA equipped with automated SR and TD flow monitoring equipment were used for the experiment. Winter rye was planted after maize harvest in 2016 and 2017 and managed as typical maize silage fields in the region, receiving fertilizer and dairy manure applications. Twelve runoff events were monitored from 4/7/16 to 6/29/17, including snowmelt events. Concentrations and loads of total nitrogen, nitrate-nitrogen, ammonium-nitrogen, total phosphorus, dissolved reactive phosphorus, and total suspended solids (an estimate of sediment concentration) were measured in SR and TD. Results indicated that average cumulative SR over the study from rye plots was 1.8-fold lower than the control. Cumulative total phosphorus, dissolved reactive phosphorus (bioavailable phosphorus), and total suspended sediment were nearly 3-fold lower for rye plots, suggesting rye mitigated phosphorus transport in SR. Most phosphorus transport was via SR whereas nitrogen loss was dominated by TD. There were no substantial differences in TD nutrient transport between rye and control plots. Results suggest that planting a winter rye cover crop following maize silage harvest mitigated sediment and phosphorus transport risk in SR compared to maize without a rye cover crop.

Technical Abstract: Nonpoint source phosphorus (P) and nitrogen (N) pollution from agriculture is a global concern. Planting a cover crop after harvesting annual crops such as maize may help mitigate nutrient transport risk to surface and groundwater. Few studies have focused on the impact of a winter rye cover crop on both surface runoff (SR) and tile drainage (TD) water quality. Here, we measured N and P losses in SR and TD from maize plots grown with and without a winter rye cover crop. Four plots (46 x 23 m) in northern New York, USA equipped with automated SR and TD flow monitoring equipment were planted with winter rye (Secale cereal) in 2016 and 2017 at 112 kg ha-1 after maize silage harvest. Plots were managed as typical silage fields for dairy farms in the region and received fertilizer and manure. Dissolved reactive P (DRP), total P (TP), nitrate-N, total N (TN), and total suspended solids (TSS) loads were monitored from 4/7/16 to 6/29/17. Results showed that cumulative SR was 1.8-fold lower for rye plots compared to control, while TD runoff was higher (83.2 vs. 66.1 mm for control). Although event runoff hydrology and loading were variable, cumulative TSS, TP and DRP losses were approximately 3-fold lower for rye plots compared to control. Cumulative TN and nitrate-N loads for TD were similar, however cumulative TN loss for SR was lower for rye plots. Surface runoff was the main pathway of P loss (>90% of DRP and TP loss) with >90% of P exported from 2017 snowmelt events. Results suggest winter rye mitigated N and P transport risk in SR compared to the common practice of leaving maize silage fields bare after harvest.