Reducing Nitrogen Loss in Subsurface Tile Drainage Water with Managed Drainage and Polymer-Coated Urea in a River Bottom Soil

Kelly A Nelson,Peter P Motavalli,Patrick R Nash

doi:10.4236/jwarp.2014.611093

Abstract

Poorly-drained, river bottom soils can be high corn (Zea mays L.) yielding environments, but saturated soil conditions often reduce corn yields. Wabash soils located in river bottoms in Northeast Missouri have not been traditionally tile drained due to high clay content which requires narrow tile drain spacings. Increased land prices in the region have increased interest in tile draining poorly-drained bottom land soils to increase corn yields which could have a deleterious effect on water quality. The objectives of the three-year study were to determine whether use of managed subsurface drainage (MD) in combination with a controlled release N fertilizer could reduce the annual amount of NO3--N loss through tile drainage water compared to free subsurface drainage (FD) with a non-coated urea application. Annual NO3--N loss through tile drainage water with FD ranged from 28.3 to 90.1 kg·N·ha-1. Nitrogen fertilizer source did not affect NO3--N loss through tile drainage water, which was likely due to limited corn uptake over the three-year study due to adverse weather conditions. Averaged over three years, MD reduced tile water drained 52% and NO3--N loss 29% compared to FD. Reduction in NO3--N loss through tile drainage water with MD compared to FD was due to reduced tile flow during the non-cropping period. Annual flow-weighted mean concentration of NO3--N in the tile water was 5.8 mg·N·L-1 with FD and 8.1 mg·N·L-1 with MD. Tile draining river bottom soils at this location for continuous corn production may not pose a health risk over the evaluated duration.

Highlights

Poorly-drained, silty clay soils in river bottoms located in Northeast Missouri and throughout the MidwesternU.S often have high soil fertility [1] and can produce high corn yields
Higher NO3− -N concentration in the tile water observed at times with managed subsurface drainage (MD) compared to free subsurface drainage (FD) over the three-year study partially offset the reduction in water drained and subsequent NO3− -N loss through tile drainage water with MD (Figure 3)
Increased NO3− -N concentration in the tile drainage water with MD compared to FD was likely due the annual reduction in tile flow and limited corn uptake of applied N which may have increase soil N concentration

Summary

Introduction

Poorly-drained, silty clay soils in river bottoms located in Northeast Missouri and throughout the MidwesternU.S often have high soil fertility [1] and can produce high corn yields. Poorly-drained, silty clay soils in river bottoms located in Northeast Missouri and throughout the Midwestern. Saturated soil conditions due to poor drainage, high seasonal water tables, and flooding due to the low landscape position often reduce corn yields. Soils of the Wabash soil series located in Northeast Missouri have a low overall soil hydraulic conductivity (Ksat = 0.01 to 0.10 μm·sec−1) due to high clay content throughout the soil profile, which requires narrow subsurface tile drain spacing. Poorly-drained Wabash soils have not traditionally been tile drained as the cost of installing subsurface tile drainage systems is relatively high. Relatively high grain prices may make tile draining poorly-drained, river bottom soils that have not traditionally been drained an economically viable management option to reduce excessive soil moisture and increase corn yields. An increased rate of water infiltration and transport out of soils with

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Conclusion