Abstract
Ammonium sulphate is widely used as a sulphur (S) fertilizer, constituting about 50% of global S use. Within nitrogen (N) management, it is well known that ammonium‐based fertilizers are subject to ammonia (NH3) volatilization in soils with pH > 7, but this has been overlooked in decision making on S fertilization. We reviewed 41 publications reporting measurements of NH3 loss from ammonium sulphate in 16 countries covering a wide range of soil types and climates. In field experiments, loss was mostly <5% of applied N in soils with pH (in water) <7.0. In soils with pH > 7.0, there was a wide range of losses (0%–66%), with many in the 20%–40% range and some indication of increased loss (ca. 5%–15%) in soils with pH 6.5–7.0. We estimate that replacing ammonium sulphate with a different form of S for arable crops could decrease NH3 emissions from this source by 90%, even taking account of likely emissions from alternative fertilizers to replace the N, but chosen for low NH3 emission. For every kt of ammonium sulphate replaced on soils of pH > 7.0 in temperate regions, NH3 emission would decrease from 35.7 to 3.6 t NH3. Other readily available sources of S include single superphosphate, potassium sulphate, magnesium sulphate, calcium sulphate dihydrate (gypsum), and polyhalite (Polysulphate). In view of the large areas of high pH soils globally, this change of S fertilizer selection would make a significant contribution to decreasing NH3 emissions worldwide, contributing to necessary cuts to meet agreed ceilings under the Gothenburg Convention.
Highlights
It has been recognised for over 50 years that surface application of ammonium-based fertilizers or urea can lead to rapid and significant evolution of ammonia (NH3) gas to the atmosphere (Gasser, 1964, and references therein)
Materials and Methods We summarised the estimations of NH3 emission factors (EFs) for ammonium sulphate proposed in documents from several major regulatory authorities internationally and from previously published literature reviews
The UK Code of Good Agricultural Practice for Reducing Ammonia Emissions (Defra, 2018), based in part on the model of Misselbrook et al (2004), does not cite an EF for ammonium sulphate but states that, to minimise volatilisation, surface application should be avoided on calcareous soil of pH >7.5 unless it can be rapidly incorporated into soil
Summary
It has been recognised for over 50 years that surface application of ammonium-based fertilizers or urea can lead to rapid and significant evolution of ammonia (NH3) gas to the atmosphere (Gasser, 1964, and references therein). Losses are often greater with urea because rapid conversion of urea-N to ammonium-N by the urease enzyme in soil increases pH in the vicinity of fertilizer particles (Rachhpal-Singh & Nye, 1986; Kirk & Nye, 1991). These well-established principles were summarised by Harrison & Webb (2001) in the context of comparing gaseous N losses from urea with those from ammonium nitrate and other forms of N fertilizer. Ammonia gas in the atmosphere can react with other substances to form particulate materials including ammonium sulphate, ammonium nitrate and ammonium chloride Human exposure to these particulates (PM10 and PM2.5) can lead to increased rates of respiratory and cardiovascular illness (Wu et al, 2016; Moldanová, et al, 2011)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
