Impacts of drainage water management on phosphorus and nitrogen losses from northern New York corn silage fields

Authors: KLAIBER, LAURA - Miner Institute; KRAMER, STEPHEN - Miner Institute; HANEY, MARK - Miner Institute; Young, Eric

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2021
Publication Date: 11/7/2021
Citation: Klaiber, L.B., Kramer, S.R., Haney, M.K., Young, E.O. 2021. Impacts of drainage water management on phosphorus and nitrogen losses from northern New York corn silage fields. Meeting Abstract. November 7-10. Salt Lake City, Utah.

Interpretive Summary:

Technical Abstract: Many agricultural soils in the Lake Champlain Basin are poorly drained and crop yields often benefit from systematic artificial subsurface tile drainage (aka, tile drainage). In addition to greater crop yield potential, tile drains can also reduce erosion and loss of particulate-bound nutrients in surface runoff. However, it is also clear that tile drainage can accelerate nitrogen (N) leaching losses while more recent studies indicate phosphorus (P) can also be readily transported to tile drain flows. Using inline drainage control structures to raise water table elevations, drainage water management (DWM) helps mitigate nutrient loss by decreasing net drainage water fluxes from tile-drained fields (generally during the non-growing season; October 1 to April 1). Few studies in the Northeast US have evaluated DWM impacts on N and P export. We initiated a paired, edge-of-field monitoring study in 2015 for two tile-drained corn silage fields (T5 and T9; 1.9 and 3.3 ha, respectively) at a northern New York research site to quantify DWM impacts on P and N losses from tile drain and surface runoff flows. Fields were tile-drained in 2014 (1.2 m average depth at 10.7 m lateral spacing) and flow to individual concrete manholes where flows are gauged continuously by small v-notch weirs. Fields are hydrologically isolated via berms/diversion ditches and surface runoff flows to topographic lows in each field edge where it directed to fiberglass flumes. Runoff was sampled at the mouth of the flume by an autosampler and nutrient loads were estimated by multiplying event flows by event mean concentrations. Both fields were drained freely (no gates in control structures) during the calibration period (October 2015 to November 2017). DWM was imposed on field T5 in late November 2017 (water table held at 0.76 m below ground for the first non-growing season and 0.33 m thereafter) and T9 remained freely drained throughout the study. Analysis of covariance was used to determine nutrient load and concentration differences for tile and total field export (surface + tile) during the treatment period. Results showed that tile flow accounted for 76 and 81% of the total drainage for T9 and T5, respectively. For both tile drain flow and total field export, peak discharge, cumulative flow, and concentrations/loads of dissolved reactive P, nitrate-N, and total N were significantly lower for DWM. While DWM had DRP and nitrate-N loading reductions of 49% and 28%, respectively, TP and sediment did not differ between DWM and free drainage. Results show that DWM has promise for mitigating N and P loads from tile systems, however further research is needed to better understand longer-term impacts on P export and crop yields for DWM.