Nutrient and sediment losses from surface runoff during bermudagrass (Cynodon dactylon L.) establishment on a levee embankment

Fertilizer applications to newly constructed levee embankments during soft armor establishment may pose an increased threat to water quality. Potential nutrient and sediment loading can impact human and aquatic organisms that rely on water resources. The objectives of this study were to 1) determine the effect of grass coverage on surface runoff 2) evaluate bermudagrass establishment between water-soluble and insoluble N sources and 3) quantify nutrient and sediment losses from surface runoff during grass establishment. In 2008, fertilizer treatments consisted of sulfur-coated urea (SCU) or urea applied at 50 kg ha-1 to runoff collection trays installed on a 30% sloped levee embankments planted with common bermudagrass (Cynodon dactylon L.). Simulated rainfall was applied at 96 mm h-1 14, 28, 42, 56 and 70 days after seeding (DAS). In 2009, ammonium nitrate (NH4-NO3) and urea-formaldehyde (UF) were applied at 100 kg ha-1. Simulated rainfall was applied for 30 minutes after the onset of continuous runoff every 14 days during bermudagrass establishment. Runoff collected from storm and simulated precipitation events was analyzed for volume, NO3-N, NH4-N, total dissolved phosphorus (TDP), and total phosphorus (TP). Other measurements included time until runoff, sediment loss, percent vegetative groundcover, and soil volumetric water content. Nitrogen applications accelerated bermudagrass growth compared to unfertilized controls for both years of the study. In 2008 and 2009, nutrient losses from initial precipitation events were 40% to 87% greater from fertilized bermudagrass than unfertilized controls. Sediment, volume, time until runoff, and nutrient losses declined as bermudagrass coverage increased, but fertilized bermudagrass did not decrease total sediment losses and runoff volumes compared to unfertilized controls for either year. In 2008, total N losses were similar between fertilizer sources (SCU and Urea) with the greatest losses of 5 mg L-1 during initial rainfall events following application. In 2009, total N losses from unfertilized grass and UF-fertilized grass were 0.49 kg ha-1 while losses from NH4-NO3 fertilized grass were 1.73 kg ha-1. Water-soluble N sources and SCU resulted in the highest N losses. Application of the slow-release N fertilizer, UF, accelerated bermudagrass establishment and limited N losses