Optimising soil P levels reduces N2O emissions in grazing systems under different N fertilisation

Title: Optimising soil P levels reduces N2O emissions in grazing systems under different N fertilisation
Authors: O'Neill, Róisín MaryGebremichael, Amanuel WoldeselassieLanigan, GaryRenou-Wilson, FlorenceMüller, ChristophRichards, Karl
Permanent link: http://hdl.handle.net/10197/13211
Date: Jul-2022
Online since: 2022-10-20T15:18:13Z
Abstract: The effect of long-term soil phosphorus (P) on in situ nitrous oxide (N2O) emissions from temperate grassland soil ecosystems is not well understood. Grasslands typically receive large nitrogen (N) inputs both from animal deposition and fertiliser application, with a large proportion of this N being lost to the environment. Understanding optimum nutrient stoichiometry by applying N fertilisers in a relative balance with P will help to reduce N losses by enabling maximum N-uptake by plants and microbes. This study investigates the N2O response from soils of long-term high and low P management receiving three forms of applied N at two different rates: a nitrate-based fertiliser (KNO3) and an ammonium-based fertiliser ([NH4]2SO4) (both at 40 Kg N ha−1), and a synthetic urine (750 Kg N ha−1). Low soil P significantly increased N2O emissions from KNO3 and (NH4)2SO4 fertilisers by over 50% and numerically increased N2O from urine by over 20%, which is suggested to be representative of the lack of significant effect of N fertilisation on N-uptake observed in the low P soils. There was a significant positive effect of soil P on grass N-uptake observed in the synthetic urine and KNO3 treatments, but not in the (NH4)2SO4 treatment. Low P soils had a significantly lower pH than high P soilss and responded differently to applied synthetic urine. There was also a significant effect of P level on potential nitrification which was nearly three times that of low P, but no significant difference between potential denitrification and P level. The results from this study highlight the importance of synergy between relative nutrient applications as a deficiency of one nutrient, such as P in this case, could be detrimental to the system as a whole. Optimising soil P can result in greater N uptake (over 12, 23 and 66% in (NH4)2SO4, KNO3 and synthetic urine treatments, respectively) and in reduced emissions by up to 50% representing a win-win scenario for farmers.
Funding Details: Teagasc
Department of Agriculture, Australian Government, Food, and the Marine
Open access funding provided by IReL
Type of material: Journal Article
Publisher: Wiley
Journal: European Journal of Soil Science
Volume: 73
Issue: 4
Start page: 1
End page: 17
Copyright (published version): 2022 The Authors
Keywords: Carbon-nitrogen-phosphorus stoichiometryNutrient use efficiencyOptimum managementTemperate grassland
DOI: 10.1111/ejss.13283
Language: en
Status of Item: Peer reviewed
ISSN: 1351-0754
This item is made available under a Creative Commons License: https://creativecommons.org/licenses/by-nc-nd/3.0/ie/
Appears in Collections:Biology & Environmental Science Research Collection
Climate Change Collection

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