a field study on the impact of the nitrification inhibitor dmpp on nitrous oxide emissions from...
TRANSCRIPT
A field study on the impact of the nitrification inhibitor DMPP on N2O emissions from a pasture in south western VictoriaHelen Suter, Humaira Sultana and Deli Chen(The University of Melbourne)
Rohan Davies and Matthew Mahoney(Incitec Pivot)
Nitrification and inhibitors
NH4+ NO3
-nitrification
(eg. Nitrosomonas)
denitrification
N2O
N2
Nitrification inhibitor eg. Dimethylpyrazole phosphate (DMPP)
Urea
hydrolysis
N2O
Experimental methodology
Treatments • Control• Urea• Urea with Entec® = Urea + DMPP ( Dimethyl pyrazole phosphate)
5 replicates/treatment
• 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
• Start date: 12 April 2010
• End date: 23 December 2010
• Fertilisation events: 7
• Gas collection: manual chambers (23 x 20 cm)
Source: Google maps
Experimental methodology
Experimental methodology : Data Collection
o Gas – N2O, CO2, CH4
• 3 samples (0, 30, 60 mins)/chamber • weekly and event driven• analysed in lab
o Soil • fortnightly • NH4
+ and NO3-
o Biomass production and N content• monthly
o Additional data• climate data• soil moisture and temperature
Results: Daily N2O emissions (April-Oct)
0
5
10
15
20
25
30
35
40
45
Calc
ulat
ed d
aily
N2O
(g/h
a)
control
urea
DMPP
fertiliser application at 40 kg N/ha
site waterlogged, no sampling
Results: Daily N2O emissions and rainfall (April-Oct)
(Total rainfall 522 mm)0
5
10
15
20
25
30
35
40
Rai
nfal
l (m
m)
0
5
10
15
20
25
30
35
Calc
ulat
ed d
aily
N 2O
(g/h
a)
control
urea
DMPP
fertiliser application at 40 kg N/ha
site waterlogged, no sampling
Results: Daily N2O emissions and daily mean maximum temperature (April-Oct)
0
5
10
15
20
25
30
35
Calc
ulat
ed d
aily
N 2O
(g/h
a)
control
urea
DMPP
fertiliser application at 40 kg N/ha
site waterlogged, no sampling
0
5
10
15
20
25
30
Tem
pera
ture
(o C)
Results: Cumulative Net-N2O emissions
0
50
100
150
200
250
300
350
400
450
Calc
ulat
ed c
umul
ative
Net
-N2O
(g/
ha) Urea
DMPP
73% reduction
fertiliser application at 40 kg N/ha
Results : soil nitrate levels
0
2
4
6
8
10
12
14
16
18
Nitr
ate
-N (k
g/ha
) Control
DMPP
Urea
Results : soil nitrate levels and potential for leaching loss
0
5
10
15
20
25
30
35
40
Rain
fall
(mm
)0
2
4
6
8
10
12
14
16
18
Nitr
ate
-N (k
g/ha
)
Control
DMPP
Urea
Results : soil nitrate levels and potential for leaching loss
0
5
10
15
20
25
30
35
40
Rain
fall
(mm
)0
2
4
6
8
10
12
14
16
18
Nitr
ate
-N (k
g/ha
)
Control
DMPP
Urea
Potential for leaching losses reduced with DMPP
Results : Dry Matter (DM) production (kg/ha)
Treatment 10-May 7-Jun* 19-Jul 3-Sep 27-Sep 21-OctCumulative(240 kg N applied)
Control 428 ± 68 106 ± 24 232 ± 45 259 ± 35 256 ± 29 454 ± 46 1736
Urea 699 ± 70 159 ± 9 569 ± 11 876 ± 82 818 ± 33 1027 ± 41 4149
Urea + DMPP 748 ± 97 207 ± 36 618 ± 71 949 ± 74 754 ± 60 1030 ± 78 4307
% increase in net DM with
DMPP18 89 14 12 -11 1 6
* 7 June sampling comes 2 months after fertilisation on 12 April
(Value is average of 5 reps ± standard error)
Results : Dry Matter (DM) production (kg/ha)
Treatment 10-May 7-Jun* 19-Jul 3-Sep 27-Sep 21-OctCumulative (240 kg N applied)
Control 428 ± 68 106 ± 24 232 ± 45 259 ± 35 256 ± 29 454 ± 46 1736
Urea 699 ± 70 159 ± 9 569 ± 11 876 ± 82 818 ± 33 1027 ± 41 4149
Urea + DMPP 748 ± 97 207 ± 36 618 ± 71 949 ± 74 754 ± 60 1030 ± 78 4307
% increase in net DM with
DMPP18 89 14 12 -11 1 6
* 7 June sampling comes 2 months after fertilisation on 12 April
Conclusions : DMPP impact on N2O emissions from a pasture
Compared 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, Robert Edis, David Hopkins, Peter and Mary-Jane Ganon, Chen Li, Marion Benfell, Jagrati Singh