Fate of nitrogen during grow-in of a golf course fairway under different nitrogen management practices

Application of N fertilizer to sandy soils may result in leaching of N resulting in contamination of ground water. Nitrogen leaching losses may be reduced by the use of slow-release fertilizers and a progressive-type application regime. This study was conducted to determine the effect of N source and application method on N leaching and establishment rate. 'Tifway 419' bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis (Burtt-Davis)] was grown on soil columns filled with Arredondo fine sand (a loamy, siliceous, hyperthermic Grossarenic Paleudult). Applications of N followed two regimes: 1) application of 4.8 g N m^-2 each week (standard), and 2) application of 1.2 g N m^-2 from week 1-3, application of 2.4 g N m^-2 from week 4-6, application of 3.6 g N m^-2 from week 7-9, and application of 4.8 g N m^-2 from week 10-12 (progressive). These regimes were used in application of four N-source treatments: 1) 100% of N as soluble N from NH₄NO₃ (AN) or (NH₄)₂SO₄ (AS), 2) 33% of N from soluble, Milorganite (MIL), and sulfur-coated urea (SCU), 3) 33% of N from soluble, MIL and isobutylidene-diurea (IBDU), and 4) 33% of N from soluble and 66% of N from MIL. The effect of application regime and N source on N leaching, turfgrass N-uptake, and turfgrass establishment were evaluated. Total N leached ranged from 70 to 180 g kg^-1 of that applied, and the progressive application regime reduced N leaching by 250 g kg^-1. Plant uptake of N ranged from 350 to 730 g kg^-1 of that applied, and was not affected by N source but was affected by application method when AN was used. The combination of slow-release N sources with soluble N under the progressive application regime produced the least N leached without adversely affecting plant N uptake or establishment rate.