Comparison of Enhanced‐Efficiency Nitrogen Fertilizers for Reducing Ammonia Loss and Improving Bermudagrass Forage Production

Abstract

The efficacy of enhanced-efficiency (EE) nitrogen (N) fertilizer formulations in reducing N loss and improving the efficiency of urea-based fertilizer products in forage production is unclear. This study compared ammonium nitrate (AN), urea, four EE urea N formulations [A/-(n-butyl) thiophosphoric triamide (NBPT)-treated urea, NBPT and dicyanamide-treated urea, a polymer-coated urea (PGU), and a maleic-itaconic copolymer-treated urea (MICPU)], urea-ammonium nitrate (UAN), and two EE UAN formulations (NBPT-treated UAN, NBPT and dicyanamide-treated UAN) in forage bermudagrass [Cynodon dactylon (L.) Pers.] production. The experimental design was a randomized complete block design with four replications in each of two sites and 2 yr (2008)(2009). Treatment applications were made at the rate of 168 kg N ha ' spring dormancy-break (ca. 30 April) and after the second harvest (ca. 25 July; total of 336 kg N ha ^ season). Response variables included trapped ammonia (NH3) and forage yield, production efficiency, N concentration, N uptake, recovery of applied N, and nitrate concentration. Urea treated with NBPT reduced NH3 volatilization and, in some situations, increased agronomic response relative to urea. Addition of NBPT produced results similar to AN and UAN, and it was never detrimental relative to untreated urea. The MIGPU treatment was ineffectual relative to urea alone. The PGU reduced NH3 volatilization and improved N concentration in the forage but did not improve other agronomic characteristics. Use of UAN solutions produced results that were generally intermediate in response between urea and ammonium nitrate and were not improved by NBPT addition. Adding NBPT can reduce NH3 volatilization and increase the efficiency of urea, but further research is necessary to understand the limits of this additive.

Soil‐Fertility Principles for Warm‐Season Perennial Forages and Sustainable Pasture Production

“…Different fertilizer technologies have been developed recently to increase crop nutrient uptake. These include slow‐release fertilizers and fertilizers that contain urease or nitrification inhibitors (Watson et al, 1998; Vaio et al, 2008; Connell et al, 2011). Field‐scale studies focused on the responses of warm‐season perennial grasses to enhanced efficiency fertilizers are scarce.…”

Growth, Herbage Accumulation, and Nutritive Value of ‘Tifton 85’ Bermudagrass as Affected by Nitrogen Fertilization Strategies

“…Ammonia volatilization can be problematic, especially when rainfall after urea application is not sufficient to incorporate the fertilizer into the soil (Fox et al, 1986). Under these conditions, N loss via ammonia volatilization can be as much as 20% of the applied N (Massey et al, 2011) with subsequent negative impacts on N use efficiency and crop production (Connell et al, 2011).…”

Nitrate Leaching, Turf Quality, and Growth Rate of ‘Floratam’ St. Augustinegrass and Common Centipedegrass

“…Thus, the influence of N source on growth rate and turf quality was determined by year within each species. Urea diffusion from PCUs may be slower than desired, particularly on thicker-coated materials such as the 41-0-0 used in this study (Connell et al, 2011). In 2008, N sources did not increase growth rate of St. Augustinegrass above the control (Table 6).…”

“…Once applied, urea is immediately hydrolyzed and nitrification can begin. Urea diffusion from PCUs may be slower than desired, particularly on thicker-coated materials such as the 41-0-0 used in this study (Connell et al, 2011). During the time required for urea diffusion across the polymer membrane, turf may be deprived of N, resulting in growth rates equal to plots receiving no N. This occurred during the establishment year for both turf species in this study.…”