Reducing Nitrogen Losses from Agriculture Using a Nitrification Inhibitor (eco-n)

Professor Keith Cameron, Professor Hong Di and Dr Jim Moir

Centre for Soil and Environmental Quality

Lincoln University, Canterbury

New Zealand

Two main nitrogen losses from agriculture

• Nitrate leaching in drainage water causes pollution of surface and groundwater

• Nitrous oxide (N2O) is given off by soil and is a potent greenhouse gas.

Methane (63.4%)

Other (1.7%)

Nitrous oxide

(34.9%)

NZ agricultural greenhouse gases

How do you measure nitrate leaching losses from a grazed pasture?

Collecting 1- tonne Templeton soil lysimeters

Underground laboratory constructed to house lysimeters under typical soil and environmental conditions

Surface of lysimeters level with surface of paddock.

Typical rainfall, temperature,

irrigation, fertiliser, pastures, and urine applied.

Going downstairs into the underground laboratory

Drainage water is collected in the underground laboratory to measure nitrate leaching losses directly from soils.

Robotic cow hoof used to simulate trampling during grazing

Results show that in dairy farming urine patches are the main sources of nitrate leaching and nitrous

oxide emissions

Most nitrate leaching comes from urine patches not from fertiliser

Ledgard et al, 2005

Improved nitrogen management is now possible with the newly developed eco-

n nitrification inhibitor.

NH4+

- - - -

NO3-

Cation exchange

Nitrate ions (NO3-) are not held by soil particles and

can easily be leached when drainage occurs

The Nitrogen Cycle(McLaren & Cameron, 1996)

NH4+

- - - -

NO3-

Cation exchange

Nitrification inhibitor ‘eco-n’ slows down the rate of nitrate

production and thus reduces the nitrate leaching

loss The Nitrogen Cycle(McLaren & Cameron, 1996)

The inhibitor temporarily reduces the activity of the nitrosomonas bacteria in the soil (Bacteriostatic effect)

Nitrification inhibitor (‘eco-n’) is applied as a fine suspension spray to improve soil N cycle

efficiency and reduce the risk of nitrate leaching

Eco-n is applied in May and July/August because most losses occur between late autumn and early spring

CHRISTCHURCH: Mean Soil Temperature (at 10cm) and Estimated Drainage (mm)

0

5

10

15

20

25

30

35

40

45

50

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMonths

Est

imat

ed D

rain

age

(mm

)

0

2

4

6

8

10

12

14

16

18

20

Soi

l Tem

per

atu

re

0C

)

Drainage (mm)

Soil Temp (C)

Drainage

eco-n eco-n

HAMILTON: Mean Soil Temperatures (at 10 cm) and Estimated Drainage (mm)

0

20

40

60

80

100

120

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Months

Est

imat

ed D

rain

age

(mm

)

0

2

4

6

8

10

12

14

16

18

20

Soil

Tem

pera

ture

(0C

)

Drainage

Soil Temp (C)

Drainage

eco-n eco-n

In North Island Eco-n is applied in May and July because leaching also occurs in the winter/early spring

Nitrate leaching

Eco-n applied twice (May plus August) reduced the nitrate concentration from urine applied in May

(Templeton soil) (Di and Cameron, 2004. NZ J Agr. Res. 47)

0

20

40

60

80

100

0 50 100 150 200 250 300

Cumulative drainage (mm)

NO

3- -N c

once

ntra

tion

(mg

L-1)

Urea 200/Urine 1000

Urea 200/Urine 1000/Eco-N (May + Aug.)

Urine only

Urine plus eco-n (May + Aug)

0

20

40

60

80

100

120

Urea 200/Urine 1000 Urea 200/Urine 1000/Eco-N (May +Aug.)

Treatments

NO

3- -N le

ach

ing

loss

(kg

N h

a-1 y

r-1) LSD (P < 0.05) = 57

Eco-n reduced the nitrate leaching loss by 76% (Templeton soil) (Di and Cameron, 2004).

Urine only Urine plus eco-n (May + Aug)

Nitrate-N Leaching - Waihora, Taupo

0

50

100

150

200

250

300

350

400

2003 2004 2005 3 year Average

Nit

rate

-N (

kg N

/ha/

yr)

Urine alone

Urine + eco-n

no urine

no urine + eco-n

Eco-n reduced nitrate

leaching by 30 – 40%

3 year trial shows that eco-n inhibitor significantly reduced nitrate leaching losses from Taupo pumice soils

Nitrous oxide greenhouse gas emissions

Nitrous oxide gas emissions are measured using gas chambers

placed on the lysimeters for 30 minutes each day.

Nitrous oxide emissions from Agricultural soilsas a percentage of New Zealand's total Agricultural

Greenhouse gas emissions in 2003

Methane (63.4%)

Other (1.7%)

Nitrous oxide(34.9%)

Source: National Inventory Report: 1990-2003 (Ministry for the Environment, April 2005)

Daily N2O-flux, Templeton lysimeters Winter Run Off Trial - 2005/06

0

100

200

300

400

500

600

700

800

Sampling date

N2O

-N fl

ux (g

/ha/

day)

Control

eco-n (10) 21st June

U1000 (3rd June)

U1000 (3rd June) eco-n (10) 21stJune

Eco-n reduced N2O emissions by 73% on Templeton soil in Canterbury, NZ (Di et al. 2007).

Eco-n reduced N2O emissions by 61% in the Waikato Horotiu soil (Di et al., 2006)

0

100

200

300

400

05/05/05 04/06/05 04/07/05 03/08/05Sampling date

Dai

ly N

2O f

lux

(g N

2O-N

ha-1

day

-1)

ControlControl + DCDUrine 1000Urine 1000 + DCDeco-n

eco-n

0

5

10

15

20

25

30

35

1990 baseline No eco-n 50% dairyland treatedwith eco-n

100% dairyland treatedwith eco-n

Gg

N2O

/yea

r

beef

sheep

dairy

National Inventory Report: 1990-2005(Ministry for the Environment, April 2007)

2005 scenarios

NZ’s Agricultural nitrous oxide emissions reduced with ‘eco-n’

Pasture production

Lincoln University

Control plot: no ‘eco-n’

Lincoln University

‘eco-n’ plot

Retaining More Nitrogen in the Soil Produces More Pasture Growth

Average Annual Pasture Yield – LUDF South Block

4 Years - 2002/03 to 2005/06 Seasons

0

4000

8000

12000

16000

20000

Pa

stu

re Y

ield

(k

g D

M h

a-1)

Inter-Urine

Inter-Urine+eco-n

Urine

Urine+eco-n

20 % 29 %

Moir et al., 2007

Equally high ME with eco-n

ME 16.9.05

0

5

10

15

Treatment

ME

(M

JM

E k

gD

M-1

)

Control

eco-n

Urine Patch (Control)

Urine Patch (eco-n)

LUDF Cumulative Pasture Yield Regression2002/03 to 2004/05 Seasons

0

2000

4000

6000

8000

10000

12000

14000

Yie

ld (k

g D

M h

a-1)

eco-n (Regression)

Control (Regression)

eco-n

Control

Apr Jun Aug Oct Dec Feb Apr

y = 13870/(1+exp(-(x-355)/67.2))Adj R2 = 0.92

y = 11451/(1+exp(-(x-356)/66.2))Adj R2 = 0.94

12.1 T

10.0 T

Conserving N with the inhibitor grows more pasture (Moir et al. 2007)

Summary

Decrease in nitrous oxide emissions

Increase in annual farm pasture production

Decrease in nitrate leaching

Research results show:

Eco-n is based on New Zealand research trials published in internationally peer reviewed science journals

1. Di HJ and Cameron KC (2002) Soil Use and Management 18: 395-403.2. Di HJ and Cameron KC (2003) Soil Use and Management 19: 184-290.3. Di HJ and Cameron KC (2004a) Soil Use and Management 20: 2-7.4. Di HJ and Cameron KC (2004b) NZ Journal of Agricultural Research 47: 351-361. 5. Di HJ and Cameron KC (2004c) Australian Journal of Soil Research 42: 927-932.6. Di HJ and Cameron KC (2005) Agriculture, Ecosystems and Environment 109: 202-212.7. Di HJ and Cameron KC (2006) Biology and Fertility of Soils 42: 472-480.8. Di HJ, Cameron KC and Sherlock (2007) Soil Use and Management 23: 1-9.9. Moir JM, Cameron KC and Di, HJ (2007) Soil Use and Management 23: 111-120.10. Clough TJ, Di HJ, Cameron KC, Sherlock, RR, Metherell AK, Clark H and Rys, G (2007)

Nutrient Cycling in Agroecosystems 78: 1-14.11. Di HJ and Cameron KC (2007) Nutrient cycling in Agroecosystems 79,281-290.12. Di HJ and Cameron KC (2008) Australian Journal of Soil Research 42: 927-932.

Lincoln University would like to thank Ravensdown Fertiliser Co-operative Ltd,

and the Pastoral Greenhouse Gas Research Consortium (PGGRC) for funding this

research.