A field study on the impact of the nitrification inhibitor DMPP on nitrous oxide emissions from pasture - Helen Suter
A field study on the impactof the nitrification inhibitorDMPP on N2O emissionsfrom a pasture in southwestern VictoriaHelen Suter, Humaira Sultanaand Deli Chen(The University of Melbourne)Rohan Davies and Matthew Mahoney(Incitec Pivot)
Experimental methodology• Location : Murroon, south west Victoria• Average annual rainfall : 660 mm• Pasture : 2 year old ryegrass seed pasture• Soil : duplex, silty loam topsoil, pHW 5.5• Grazing : sheep grazing (prior to trial)• Plot size : 2 m x 1 m• Application rate: 40 kg N/ha Source: Google maps• Start date: 12 April 2010• End date: 23 December 2010• Fertilisation events: 7• Gas collection: manual chambers (23 x 20 cm)
Experimental methodology : Data Collectiono Gas – N2O, CO2, CH4 • 3 samples (0, 30, 60 mins)/chamber • weekly and event driven • analysed in labo Soil • fortnightly • NH4+ and NO3-o Biomass production and N content • monthlyo Additional data • climate data • soil moisture and temperature
Results: Daily N2O emissions (April-Oct) 45 control fertiliser application at 40 kg N/ha 40 urea DMPP 35Calculated daily N2O (g/ha) 30 25 20 site waterlogged, no sampling 15 10 5 0
35 control fertiliser application at 40 kg N/ha 30 urea DMPP 25 Calculated daily N 2O (g/ha) 20 site waterlogged, no samplingResults: 15Daily N2O 10emissions andrainfall (April-Oct) 5 0 40 35 30 Rainfall (mm) 25 20 15 10 5 0(Total rainfall 522 mm)
35 control fertiliser application at 40 kg N/ha 30 urea DMPP 25 Calculated daily N 2O (g/ha) 20 site waterlogged, no samplingResults: 15Daily N2O 10emissions anddaily mean 5maximum 0temperature(April-Oct) 30 25 Temperature (oC) 20 15 10 5 0
Conclusions : DMPP impact on N2O emissions from a pastureCompared to urea, DMPP :• delayed formation of NO3--N at some times of the year with greatest impact during high rainfall periods – April, June, August• reduced Net-N2O emissions: – over a 6 month period by 73% – at particular times of the year (high temp/rainfall) but not always• increased the longevity of supply of N for plant growth for 60 days leading to an 87% increase in DM production (June sampling) compared to urea
AcknowledgementsDebra Turner, Yuntong Liu, Xing Chen, RobertEdis, David Hopkins, Peter and Mary-JaneGanon, Chen Li, Marion Benfell, Jagrati Singh
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