Use of ammonium sulphate as a sulphur fertilizer: implications for ammonia volatilization

A - Papers appearing in refereed journals

Powlson, D. S. and Dawson, C. J. 2021. Use of ammonium sulphate as a sulphur fertilizer: implications for ammonia volatilization. Soil Use and Management.

AuthorsPowlson, D. S. and Dawson, C. J.

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. In temperate climates emission from soils of pH >7.0 would decrease from 35.7 to 3.6 t NH3 per kt ammonium sulphate replaced. Other sources of S are readily available including 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 selection of S fertilizer would make a significant contribution to decreasing NH3 emissions worldwide, contributing to necessary cuts to meet agreed ceilings under the Gothenburg Convention.

KeywordsAmmonium sulphate; Sulphur; Fertilizer; Ammonia; Volatilization; Gothenburg Convention
Year of Publication2021
JournalSoil Use and Management
Digital Object Identifier (DOI)
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeS2N - Soil to Nutrition - Work package 1 (WP1) - Optimising nutrient flows and pools in the soil-plant-biota system
Publisher's version
Accepted author manuscript
Supplemental file
Supplemental file
Output statusPublished
Publication dates
Online30 May 2021
Publication process dates
Accepted26 May 2021
PublisherBritish Society of Soil Science (BSSS)

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