Growing season nitrate leaching as affected by nitrogen management in irrigated potato production

Abstract

AbstractNitrate leaching from potato (Solanum tuberosum L.) production is of great concern because of its potential effects on water resources. Suction lysimeters were used in combination with a one‐dimensional flow model to quantify NO3–N leaching under irrigated potato produced on sandy soils near Québec City, QC, Canada. The 3‐yr (2010−2012) study compared a single application of polymer‐coated urea (PCU) and split‐applied soluble N fertilizers (ammonium nitrate, AN; ammonium sulfate, AS) at three N rates (120, 200, and 280 kg N ha−1) in addition to an unfertilized control. Fertilizer N application increased total seasonal NO3–N leaching. A single application of PCU increased total seasonal NO3–N leaching in 2011 compared with AN and AS, which was attributed to a greater soil NO3–N concentration under the PCU treatment in combination with increased rainfall during the tuber bulking phase (60−90 d after planting). Total seasonal NO3–N leaching in 2012 was reduced with PCU and AS compared with AN, which was attributed to reduced soil NO3–N concentrations between planting and hilling when rainfall was high. Regardless of the fertilizer N source, NO3–N leaching was primarily driven by precipitation, as leaching occurred when elevated soil NO3–N concentrations coincided with excess water in the soil. The results suggest that a single application of PCU is an effective strategy for reducing NO3–N leaching in years when there is significant rainfall during the period between planting and hilling.