Irrigation Scheduling with Soil Gas Diffusivity as a Decision Tool to Mitigate N 2 O Emissions from a Urine-Affected Pasture

Camille Rousset, Timothy J. Clough, Peter R. Grace, David W. Rowlings and Clemens Scheer
Additional contact information
Camille Rousset: Department of Soil and Physical Sciences, Lincoln University, P.O. Box 85084, Lincoln 7647, New Zealand
Timothy J. Clough: Department of Soil and Physical Sciences, Lincoln University, P.O. Box 85084, Lincoln 7647, New Zealand
Peter R. Grace: Institute for Future Environment, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia
David W. Rowlings: Institute for Future Environment, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia
Clemens Scheer: Institute for Future Environment, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4000, Australia

Agriculture, 2021, vol. 11, issue 5, 1-15

Abstract: Pastures require year-round access to water and in some locations rely on irrigation during dry periods. Currently, there is a dearth of knowledge about the potential for using irrigation to mitigate N 2 O emissions. This study aimed to mitigate N 2 O losses from intensely managed pastures by adjusting irrigation frequency using soil gas diffusivity ( D p /D o ) thresholds. Two irrigation regimes were compared; a standard irrigation treatment based on farmer practice (15 mm applied every 3 days) versus an optimised irrigation treatment where irrigation was applied when soil D p /D o was ≈0.033 (equivalent to 50% of plant available water). Cow urine was applied at a rate of 700 kg N ha −1 to simulate a ruminant urine deposition event. In addition to N 2 O fluxes, soil moisture content was monitored hourly, D p /D o was modelled, and pasture dry matter production was measured. Standard irrigation practices resulted in higher ( p = 0.09) cumulative N 2 O emissions than the optimised irrigation treatment. Pasture growth rates under treatments did not differ. Denitrification during re-wetting events (irrigation and rain) contributed to soil N 2 O emissions. These results warrant further modelling of irrigation management as a mitigation option for N 2 O emissions from pasture soils, based on D p /D o thresholds, rainfall, plant water demands and evapotranspiration.

Keywords: N 2 O emissions; automatic chambers; optimised irrigation; modelled D p /D o; pasture management (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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