Soil nitrogen supply and N fertilizer losses from Australian dryland grain cropping systems

L. Barton, F. C. Hoyle, P. R. Grace, G. D. Schwenke, C. A. Scanlan, R. D. Armstrong, M. J. Bell

Research output: Chapter in Book/Conference paperChapterpeer-review


There is a global imperative to satisfy the demand for grain production and minimize environmental impacts associated with applying nitrogen (N) fertilizers. Soil is critical to the regulation of N supply and loss from agricultural systems. We summarize field-based measurements of these pathways for Australian dryland (rainfed) grain cropping soils in three agroclimatic cropping regions. In situ net N mineralization rates have been widely reported from Australian dryland cropping soils, with up to 285 kg N ha− 1 mineralizing during the growing season and up to 190 kg N ha− 1 accumulating during the fallow between harvest and sowing of the next crop. Ammonia volatilization measurements are sparse and cover few Australian dryland cropping soils, with field-measured losses ranging from 0% to 34% of applied N. Nitrous oxide emissions have been quantified for all key Australian grain growing regions and the median annual rate is low (0.19 kg N ha− 1 yr− 1). Dinitrogen losses via denitrification are poorly understood with evidence that they may be substantial (> 50% of N fertilizer applied) from soils high in clay or organic carbon. Our understanding of nitrate leaching losses comes largely from coarse-textured, free-draining soils that have not received N fertilizer. Long-term studies investigating all key soil N supply and loss pathways and using a combination of field-based measurements, laboratory-based process studies, and modeling are required to advance our understanding of soil N supply and losses from contemporary and future dryland cropping systems in Australia.

Original languageEnglish
Title of host publicationAdvances in Agronomy
EditorsDonald L. Sparks
PublisherAcademic Press
Number of pages52
ISBN (Print)9780323989572
Publication statusPublished - Jan 2022


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