Abstract
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 language | English |
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Title of host publication | Advances in Agronomy |
Editors | Donald L. Sparks |
Publisher | Academic Press |
Chapter | 1 |
Pages | 1-52 |
Number of pages | 52 |
Volume | 174 |
ISBN (Print) | 9780323989572 |
DOIs | |
Publication status | Published - Jan 2022 |