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No evidence for higher agronomic N use efficiency or lower nitrous oxide emissions from enhanced efficiency fertilisers in aerobic subtropical rice

Citation

Rose, TJ and Quin, P and Morris, SG and Kearney, LJ and Kimber, S and Rose, MT and Van Zwieten, L, No evidence for higher agronomic N use efficiency or lower nitrous oxide emissions from enhanced efficiency fertilisers in aerobic subtropical rice, Field Crops Research, 225 pp. 47-54. ISSN 0378-4290 (2018) [Refereed Article]


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DOI: doi:10.1016/j.fcr.2018.06.001

Abstract

Enhanced efficiency nitrogen (N) fertilisers (EENFs) contain chemical urease or nitrification inhibitors, or physical barriers (e.g. polymer coating) to minimise the rapid build-up of nitrate (NO3-) in soils. They have the potential to improve N use efficiency and lower N2O emissions from soils. However, evidence of the efficacy of EENFs in warm, wet subtropical conditions is lacking. We therefore developed N response curves (0, 30, 60, 90, 120 and 150 kg N ha-1) for urea, polymer coated urea (PCU), 3,4-dimethylpyrazole phosphate (DMPP)-urea (Entec), N-(n-butyl) thiophosphoric triamide (NBPT)-urea (Green urea) and a carbon-coated urea (Black urea) in subtropical, aerobic rice (Oryza sativa L) crops in two fields with contrasting soils (Gleysol and Histosol), and quantified N2O emissions from nil-N and 90 kg N ha-1 treatments for all EENFs and urea. In the Gleysol, cumulative in-crop N2O emissions were relatively high (approximately 2 kg N2O-N ha-1 season-1 with 90 kg N ha-1 applied) with no significant mitigation from any EENFs compared to urea. Grain yield data fitted with an exponential model indicated that 95% of the estimated maximum grain yield (6.8 t ha-1 at 14% moisture) was achieved with 81 kg N ha-1 for the urea treatment. The yield response curves for all tested EENF products did not differ significantly from the urea-N yield response curve. In the Histosol, cumulative in-crop N2O emissions were negligible (around 0.05 kg N2O-N ha-1 season-1), with no significant difference (p < 0.05) between N fertiliser or nil-N treatments, and 95% of the estimated maximum grain yield (5.63 t ha-1 at 14% moisture) was achieved with only 11 kg N ha-1 for urea. There was no evidence that EENFs could achieve the maximum yield at a lower applied N rate. We hypothesised that the low soil pH of 4.9 (1:5 CaCl2 extract) may have inhibited nitrification in the Histosol, leading to low N2O emissions and a limited response to N fertiliser. Ultimately, the results of this study found no evidence that EENF products could improve agronomic N use efficiency or lower N2O emissions in the two aerobic rice crops studied.

Item Details

Item Type:Refereed Article
Keywords:aerobic rice; DMPP; Entec; NBPT; polymer coated urea; urea
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Horticultural production
Research Field:Horticultural crop growth and development
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the agricultural, food and veterinary sciences
UTAS Author:Quin, P (Mr Peter Quin)
ID Code:152605
Year Published:2018
Web of Science® Times Cited:17
Deposited By:Research Division
Deposited On:2022-08-22
Last Modified:2022-09-15
Downloads:0

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