Fate and recovery of nitrogen applied as slow release brown coal-urea in field microcosms: 15N tracer study

Biplob K. Saha; Michael T. Rose; Lukas Van Zwieten; Vanessa N. L. Wong; Terry J. Rose; Antonio F. Patti

doi:10.1039/D2EM00482H

Fate and recovery of nitrogen applied as slow release brown coal-urea in field microcosms: ¹⁵N tracer study†

Biplob K. Saha,

*^a Michael T. Rose,^b Lukas Van Zwieten,^b Vanessa N. L. Wong,^c Terry J. Rose^d and Antonio F. Patti^a

Author affiliations

* Corresponding authors

^a School of Chemistry, Monash University, Clayton, Victoria, Australia
E-mail: bksaha@bau.edu.bd

^b NSW Department of Primary Industries, Wollongbar Primary Industries Institute, Wollongbar, NSW, Australia

^c School of Earth, Atmosphere & Environment, Monash University, Clayton, Victoria, Australia

^d Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia

Abstract

The over-use of synthetic nitrogen (N) fertilisers for crop production can cause environmental pollution through leaching and gaseous losses, resulting in low N use efficiency (NUE). Previous work has shown that brown coal (BC) combined with urea can slow down the fertiliser-N release to better synchronise soil N supply with crop N demand. The study aimed to evaluate the impact of granulated BC-urea (BCU) applied to sweet corn on NUE, fate and recovery of fertiliser-N using an ¹⁵N tracer technique. In this in-field microcosm study, 10 atom percent enriched ¹⁵N-labelled urea (46% N) and BCU (20% N) were applied as N fertilisers at rates of 90 or 180 kg N ha⁻¹. On average, BCU fertiliser reduced the urea-derived ¹⁵N losses as nitrous oxide (N₂O) by 64%, ammonia (NH₃) by 73% and downward movement of total N by 59% compared to urea. Reduced losses of applied BCU fertiliser-¹⁵N were associated with significantly increased microbial immobilisation, soil retention and availability of fertiliser-¹⁵N to plants for longer periods of time, compared with urea. As a result, BCU enhanced cob yield by an average of 23%, ¹⁵N uptake by 21% and fertiliser NUE by 21% over urea. The plant recovery of fertiliser-¹⁵N was significantly higher from BCU (59%) than the recovery from urea (38%). Moreover, mining of native soil-N was lower when the N-fertiliser source was BCU cf. urea, suggesting that BCU could be used as a more N-efficient alternative to urea in cropping systems.

This article is part of the themed collection: Geochemistry

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Article information

DOI: https://doi.org/10.1039/D2EM00482H
Article type: Paper
Submitted: 24 Nov 2022
Accepted: 08 Feb 2023
First published: 08 Feb 2023

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Environ. Sci.: Processes Impacts, 2023,25, 648-658

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Fate and recovery of nitrogen applied as slow release brown coal-urea in field microcosms: ¹⁵N tracer study

B. K. Saha, M. T. Rose, L. Van Zwieten, V. N. L. Wong, T. J. Rose and A. F. Patti, Environ. Sci.: Processes Impacts, 2023, 25, 648 DOI: 10.1039/D2EM00482H

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Environmental Science: Processes & Impacts