Ammonia volatilization from nitrogen fertilizers applied to cereals in two cropping areas of southern Australia

Abstract

As farmers in southern Australia typically apply nitrogen (N) to cereal crops by top-dressing with ammonia (NH 3 ) based fertilizer in late winter or early spring there is the potential for large losses of NH 3 . This paper describes the results of micrometeorological measurements to determine NH 3 loss and emission factors following applications of urea, urea ammonium nitrate (UAN), and ammonium sulfate (AS) at different rates to cereal crops at two locations in southern Australia. The amounts of NH 3 lost are required for farm economics and management, whilst emission factors are needed for inventory purposes. Ammonia loss varied with fertilizer type (urea [ UA-N [ AS) and location, and ranged from 1.8 to 23 % of N applied. This compares with the emission factor of 10 % of applied N advocated by IPCC ( 2007). The variation with location seemed to be due to a combination of factors including soil texture, soil moisture content when fertilizer was applied and rainfall after fertilizer application. Two experiments at one location, 1 week apart, demonstrated how small, temporal differences in weather conditions and initial soil water content affected the magnitude of NH 3 loss. The results of these experiments underline the difficulties farmers face in timing fertilization as the potential for loss, depending on rainfall, can be large.

Nitrogen release from urea with different coatings

“…Rapid dissolution of granules and urea release into the soil solution is followed by urea hydrolysis and subsequent NH 4 + formation, a process that consumes hydrogen protons . Given the instability of NH 4 + in alkaline conditions, it is converted to NH 3 , which is lost in gas form . Therefore, NH 3(g) ‐N losses are more pronounced in fast‐release fertilizers, such as G1, compared to G2 and G3 (Fig.…”

“…6,7 Given the instability of NH 4 + in alkaline conditions, it is converted to NH 3 , which is lost in gas form. 21,22 Therefore, NH 3(g) -N losses are more pronounced in fast-release fertilizers, such as G1, compared to G2 and G3 (Fig. 3).…”

Nitrogen fluxes from irrigated common‑bean as affected by mulching and mineral fertilization

“…In an irrigated common-bean crop system in the Brazilian Cerrado, with broadcasted urea, Cruvinel et al (2011) found an emission factor for N 2 O-N of 0.20%. The emission of N 2 O-N found in the present study was equivalent to that measured by Metay et al (2007) Turner et al (2012) found NH 3 -N losses ranging from 1.8 to 23% of the added N fertilizers in different cropping systems. They attributed the variability of these results to soil-climate conditions, such as soil moisture, temperatures, and wind speed.…”

Tillage does not increase nitrous oxide emissions under dryland canola (Brassica napus L.) in a semiarid environment of south-eastern Australia

“…With an extremely low EF (0.05%) for N 2 O in this dry environment (Table 4), the majority of the gaseous loss was probably from NH 3 and N 2 loss. Volatilisation of NH 3 could be significant (Freney et al 1983;Turner et al 2012) as N was top-dressed and no significant rainfall fell until 5 days after N was applied (17 mm, Fig. 1).…”