Online

Griffith, Keegan E.

Plant and Soil Science

2019

M.S.

Cover crops have the potential to reduce environmental impacts of corn production. The objective of this study was to quantify differences in nitrogen (N) and phosphorus (P) loading between corn plots with or without a winter rye cover crop (Secale cerale). Four field plots (30 x 46 m) in Chazy, NY with edge-of-field monitoring were used for the study. Two plots were randomly assigned a rye cover crop treatment and planted with a grain drill at a rate of 112 kg ha-1 after corn silage harvest in 2015 and 2016. Continuous water flows were monitored from surface runoff and tile drain hydrologic pathways dur-ing runoff events. Soluble reactive P (SRP), total P (TP), nitrate-N, total N (TN), and to-tal suspended solids (TSS) concentrations were measured and multiplied by runoff vol-umes to estimate nutrient export. Surface runoff from rye plots had lower nutrient loss compared to control plots. Cumulative nitrate-N exports were similar between treatments (15.7 vs. 14.8 kg nitrate-N ha-1 for rye and control, respectively). Cumulative TN exports were numerically higher for control plots compared to rye plots, (18.8 vs. 21.4 kg TN ha-1). Cumulative TP and SRP exports (surface + tile) for rye were 2.2 and 3-fold greater than control plots, (0.51 vs. 1.19 kg TP ha-1 and 0.33 vs. 0.96 kg SRP ha-1). Total P and SRP loads in surface runoff were 3.0-fold greater for control plots compared to rye plots (0.36 vs. 1.12 kg TP ha-1 and 0.32 vs. 0.94 kg SRP ha-1). TSS load in surface runoff was numerically higher for control plots compared to rye (5.7 vs. 20.6 kg ha-1). Cumulative surface runoff was 1.8-fold greater in control plots compared to rye plots (112.6 mm vs. 207.7 mm), while cumulative tile runoff was numerically higher in rye plots compared to control (83.2 mm vs. 66.1mm). Snowmelt events contributed the majority of phosphorus losses (96% of SRP and 92% of TP), emphasizing the need to implement management techniques that reduce P transport risk during the non-growing season. Winter rye re-duced snowmelt TP export by 3-fold compared to the control plots (0.33 kg TP ha-1 and 1.03 kg TP ha-1). The winter rye cover crop planted after corn silage harvest effectively reduced erosion and P transport in surface water runoff compared to corn silage left fal-low after harvest. In addition to significantly reducing P exports, farms have the option of harvesting rye as a forage crop and double cropping with corn. In this way, more total forage is possible for the farm in addition to offering environmental conservation and wa-ter quality benefits.