Nitrogen use efficiency in grazing systems: options and new innovations

Cameron Gourley and Kevin Kelly (Department of Primary Industries Victoria), Helen Suter (University of Melbourne), Cecile de Klein (AgResearch NZ),

Michael Russelle (USDA)

• Nitrogen flows and transformations

• using dairy farms as our model

• Where are the major flows and transformations?

• How efficiently do we currently use nitrogen?

• Nitrogen efficiency at a range of scales

• Where are the opportunities for improved N efficiency?

• Future innovative and integrated approaches

Feed

Fertilizer

Animals

Bedding

N fixation

Precipitation

Crops Silage, hay

Animals

Manure

Milk

Irrigation

Dairy cows

ManurePasture / crops

SoilManure

INPUTS OUTPUTS

RunoffGaseousLeaching Soil accumulation

LOSSES

Within - Farm

Seed

Nitrogen flows and transformations

Whole - Farm

Feed

Fertilizer

Animals

Bedding

N fixation

Precipitation

Crops Silage, hay

Animals

Manure

Milk

Irrigation

Dairy cows

ManurePasture / crops

SoilManure

INPUTS OUTPUTS

Seed

160

8180

11

0

0

0

97

0

0

4380

335

34storage

11

336160

Whole-farm N surplus = 250 kg N/ha/year

N use efficiency = 29%

Victorian dairy farm

• 167 cows• 67 ha• 2.9

cows/ha• 29%

reliant imported feed

Whole-farm N Use Efficiency

USACanadaEuropeNew ZealandWestern Australia Australia-wide

215 to 568 kg ha-1Not available235 to 870 “ “150 to 550 “ “63 to 840 “ “88 to 808 “ “

14 to 5525 to 6419 to 4018 to 378 to 5514 to 49

Rotz et al., 2006Hristov et al., 2006Raison et al., 2006Ledgard et al., 2004Ovens et al., 2008Gourley et al., 2012

Farm Inputs : Farm Outputs Total Farm N Inputs

• 41 commercial dairy farms• Differing production systems

• National dairy regions• Stocking rates• Reliance on imported feed• N fertiliser use

Gourley et al. 2012, Animal Production Science

0

20

40

60

0 10000 20000 30000 40000

Milk Production (L/ha)

Wh

ole

-Fa

rm N

Eff

icie

nc

y (

%)

5

15

25

35

45

55

N B

ala

nc

e (

g/L

mil

k p

rod

uc

ed

)

Whole-farm NUE14 – 49%

Median 28%

21 g N/L

7 g N/L

45 g N/L

Whole-farm N Use Efficiency

Impact of stocking rate on nitrogen use efficiency (NUE) and nitrogen losses on a grazing dairy farm in Western Australia (M. Staines, 2009)

Parameter Stocking rate (cows ha-1)

1.25 1.50 1.75 2.00 2.25

Surplus N (kg ha-1) 57 125 189 298 385

Whole-farm NUE (%) 53 36 32 24 20

WA dairy farms 2005 to 2008 (Red Sky Agricultural).

y = 289 + 2.84x R² = 0.05

-$2,000

-$1,000

$0

$1,000

$2,000

$3,000

0 100 200 300 400

N fertiliser use (kg/ha/year)O

pera

ting

prof

it ($

/ha/

year

)

y = 289 + 2.84x R² = 0.05

-$2,000

-$1,000

$0

$1,000

$2,000

$3,000

0 100 200 300 400

N fertiliser use (kg/ha/year)O

pera

ting

prof

it ($

/ha/

year

)

Fertiliser

Dairy cows

ManurePasture / crops

Soil0

500

1000

1500

2000

2500

0 100 200 300 400 500

N fertiliser use (kg N/ha/yr)

Milk

so

lids

(kg

/ha/

yr)

DPI Farm Monitor data – Courtesy Andrew Smith]

Feed Nitrogen Use EfficiencyInput to Output Parameters N Input Range NUE Range

(%) Source

512 to 666 g cow-1d-1 26 to 33 Powell et al., 2006a Feed to Milk (Feed-NUE) 289 to 628 “ “ “

200 to 750 “ “ “ 496 to 897 “ “ “ 838 to 1360 “ “ “

22 to 29 21 to 32 21 to 36 16 to 24

Kebreab et al., 2001 Castillo et al., 2000 Chase, 2004 Aarts et al., 2000

1

Dairy cows

Pasture / crops

Soil

PurchasedFeed

Manure

Milk

y = -0.0003x + 0.3547

y = -0.0003x + 0.398

0.10

0.15

0.20

0.25

0.30

0.35

0.40

300 400 500 600 700 800 900

Fee

d N

Use

Eff

icie

ncy

y = -0.0003x + 0.3547

y = -0.0003x + 0.398

0.10

0.15

0.20

0.25

0.30

0.35

0.40

300 400 500 600 700 800 900

Vic - Spring

Vic - Summer

- Spring- Spring

- Summer- Summer

N intake (g cow -1 day -1)

South west Victoria

Gippsland

Northern irrigation

North east

Crude protein content of perennial pastures in Victoria throughout the year. Doyle et al. (2000)

Feed N use efficiency and daily loads excreted by lactating cows from 43 dairy farms over 5 visits

N use efficiency

N Excreted (g N/cow/day)

Average 20.8 432

Min 10.5 199

Max 35.1 792

Aarons et al., 2010

6 - 25%

8 - 45%

40 - 85%

SW Victorian dairy farm

• 540 cows• 460 ha• 1.2 cows/ha• 42% reliant

imported feed

Targeted mitigation (Nitrification Inhibitors)

Identify and train group leaders

Predict location of stock camps

Slide courtesy Keith Betteridge, AgResearch NZ

Surpluses of Nitrogen in modern agricultural production systems are inevitable and likely to increase with increasing inputs

Opportunities to improve nitrogen use efficiency through:Prominent role of ‘whole-farm’ N balances and use efficienciesStrategic fertiliser nitrogen inputs

variability in pasture response; Fertiliser forms, rates, timing and placement

Pasture growth stimulants (greater DM/unit N applied)Reducing feed N intakes, reduced excreta concentrationsGreater capture, reuse and redistribution of excreted N

Separate dung and urine; reduce loss, improved applicationRestricting grazing (avoid treading damage) Mop-up cropsNitrification inhibitors

Conclusion

Dairy cows

Pasture / crops

Soil

PurchasedFeed

Fertiliser Manure

Milk

NZ CATCHMENT STUDY

•Farm survey results

•OVERSEER farm loss estimates

Rate of efficiency gain < Rate of productivity increase

+ 39%

– 17 %

de Klein & Monaghan (2011)

PACKAGE OF OPTIONS – “MORE FOR LESS”

Aim Potential options

More milk per cow or per unit DM intake

More DM per unit of N input

Reduce N loss risk

• Higher genetic merit cows• Lower replacement rates• Better feeding to improve animal condition• Better quality pasture/crops/supplements• Low N feed• Restricting grazing (avoid treading damage)• Mop-up crops• Exploit variability (pasture response)• Fertiliser/manure management • Nitrification inhibitors or growth stimulants

• Nitrification/urease inhibitors• Restricted grazing• Exploit variability • Feeding to divert N to dung• Riparian and wetland management

BUT – NOT JUST A SOIL ISSUE

Rate of efficiency gain > Rate of productivity increase

Beukes et al (2011)

41% reduction

NITRIFICATION INHIBITORS (DCD) – N LEACHING LOSS FROM GRAZED PASTURE

Monaghan et al (2009)

MITIGATING SOIL N LOSS CAN HELP! e.g. Nitrification inhibitors

N2O emissionsAverage reduction: 57%

de Klein et al (2011)

Application of Milk Urea Nitrogen Values

MUN Mirrors BUN(Gustafsson & Palmquist, 1993)

BUN MUN(FQ)

MUN(PM)

MUN(AM)

MUN (Weighted avg.) =17.0 mg/dl

MUN (AM/PM avg.) =20.7 mg/dl

Courtesy Glen Broderick, USDA-ARS-USDFRC, Madison, WI

Application of Milk Urea Nitrogen Values

MUN & Dietary CP Content(Nousiainen et al., 2004)

Courtesy Glen Broderick, USDA-ARS-USDFRC, Madison, WI

Application of Milk Urea Nitrogen Values

Nousiainen et al.

Kauffman & St. Pierre

Jonker et al.

If you can track MUN, you can predict Urinary N output (g/d) (Nousiainen et al., 2004)

U

rina

ry N

(g/

d)

Application of Milk Urea Nitrogen Values

You can predict Urinary N output (g/d) even betterfrom MUN Output (g/d) & Dietary CP (%) (MTT Data)

(Urinary-N = NI - Milk-N - Fecal-N)

Urinary N = -178 + 12.4*MUN output + 2.08*[CP]

Urinary N = -178 + 12.4*MUN output + 2.08*[CP]

Uri

nary

N =

Fee

d N

– M

ilk N

– F

ecal

N

Urinary N = -178 + 12.4*MUN output + 2.08*[CP]

Huhtanen et al., 2007

r2 = 0.972

Courtesy Glen Broderick, USDA-ARS-USDFRC, Madison, WI

Application of Milk Urea Nitrogen Values

MUN Suggestions for the Farm (AgSource Coop.)

1. Establish MUN Baselines.• 2. Get MUN Values Under Standard Conditions • (Same Milking; Group Means; Same Assay).• 3. Exclude Cows with Mastitis & < 30 DIM.4. Number of Cows to Test for MUN:

a. > 50% of Each Group or Herd (AgSource advice)b. 4 Cows, ± 2 Units;

16 Cows, ± 1 Unit (Broderick & Clayton, 1997)5. Follow MUN Trends in Archived Data.

Courtesy Glen Broderick, USDA-ARS-USDFRC, Madison, WI