Ammonia loss from urea in grassland and its mitigation by the new urease inhibitor 2-NPT

Abstract

SUMMARYFollowing the surface application of granulated urea to grassland, high ammonia (NH 3 ) losses of up to 30% have been reported. The addition of a urease inhibitor (UI) to urea granules could be a way to abate these losses. Field experiments were conducted at two intensive grassland sites in 2007 and 2008 to evaluate the potential of the new UI N-(2-nitrophenyl) phosphoric triamide (2-NPT; concentrations of 0·75, 1·0 and 1·5 g N/kg) to reduce NH 3 emissions resulting from the application of granulated urea. Ammonia losses were continuously measured on plots fertilized with urea, urea + 2-NPT, calcium ammonium nitrate and a control (0N). The measurements were made with a dynamic chamber system. All measurement periods were started after a period of precipitation with a following rainless period being forecasted. Results over measurement periods of 10 days following fertilization are presented. Ammonia losses following the application of granulated urea varied between 4·6 and 11·8 kg N/ha, corresponding to 4·2 up to 14·0% of the applied nitrogen. The addition of 2-NPT to urea granules at three concentrations significantly reduced NH 3 losses by 69-100%. Comparable losses of NH 3 were observed for urea containing the UI 2-NPT as well as calcium ammonium nitrate, and were not significantly different from the control treatment. No relationships between losses, meteorological factors and soil moisture were observed. The addition of the UI 2-NPT to urea granules applied on grassland effectively reduced NH 3 losses.

Agronomic efficiency of NBPT as a urease inhibitor: A review

“…On the other hand, increasing N rates [22] , [69] , the application of urea over crop residues or to soils with high moisture and temperature, usually cause enhanced NH 3 loss [13] , [22] and hence, makes the use of urease inhibitors more attractive as a tool to increase N use efficiency. Conversely, low temperature or dry conditions may limit urea hydrolysis and, thus NH 3 losses [13] , [32] .…”

“…A formulation containing NBPT and NPPT (N-(n-propyl) thiophosphoric triamide) has been successfully tested [30] , [31] and has reached the market in the past two years under the brand name Limus. A new urease inhibitor, N-(2-nitrophenyl) phosphoric triamide (2-NPT), was developed in Germany in the early 2000s, has been tested under field conditions [32] and is also reaching the market, which is, so far, amply dominated by NBPT. They are all urea analogues.…”

Ammonia losses from urea applied to winter wheat over four consecutive years and potential mitigation by urease inhibitors

“…A dynamic chamber system was used for NH 3 measurements (Khalil et al, 2009;Schraml et al, 2016). These open-top chambers (area 0.125 m 2 , height 0.40 m, volume 0.05 m 3 ; Fig.…”

A minireview on what we have learned about urease inhibitors of agricultural interest since mid-2000s

“…1 ), lowered NH 3 volatilization by 26 to 83% from Luvisol (field conditions), causing a 2–3-day delay in the peak of gas emission [22] . As for a field experiment carried out with Lolium perenne (perennial ryegrass) cultivated either in Endofluvic Chernozem or Cambisol, 2-NPT alleviated NH 3 losses by 69–100% when used at concentrations in the range from 0.75 to 1.5 g urea-N kg 1 , while urea by itself led to NH 3 volatilization corresponding to up 14% of total N applied [23] .…”