Agronomic values of

anaerobically digested cattle manure (ADM)

Xiying Hao

Agriculture and Agri-Food Canada,

Lethbridge Research Centre

Xiying.hao@agr.gc.ca

Presented at 2014 Agri-Energy Forum, Pacific Agricultural Show

Livestock

• Current trend is towards large confined operations

o Produce huge quantities of manure

o Applied to relatively a small land area

• Alberta has 4.9 M cattle (40% of the national herd)

o County of Lethbridge licensed feedlot capacity: ~900,000 head

o Several feedlots >25,000 head

• Manure is disposed of rather than used as fertilizer

• Manure management is becoming a environmental issue

Land application

Livestock manure handling

Stockpiling

Composting

Bio-digestion Manure in feedlot pen

Digestate

• Anaerobic digestion (AD) of animal manure is an

environmentally attractive option

• Anarerobically digested manure (ADM), also called

“digestate,” is one of the final by-products of the biogas

energy industry

• ADM is rich in available N and P

5

5

Objective:

• To investigate agronomic values of the AD o Barley forage yield

o Forage barley nutrient uptake and quality

• Soil quality

• Greenhouse gas emission

Materials and methods

• Five treatments and two application rates

o (1) control: no amendment (CK)

o (2) fresh manure (M and M2)

o (3) ADM (D and D2)

o (4) liquid in ADM removed to produce separated solids

(SS and SS2)

o (5) SS processed into pellets (PE and PE2)

Materials and methods

Materials:

• Fresh cattle manure (33-50% solid)

• Digestate (4-9% solid)

• Separated solids (24-44% solid)

• Pellets (65 to 80% solid)

Experimental sites

• St. Albert (Central Alberta)

• Lethbridge (Southern Alberta)

Biogas plant

Vegreville, AB

Materials and methods

• Two rates (Assuming 50% TN available for current crop year):

– 100 and 200 kg N per ha per year for Lethbridge

– 135 and 270 kg N per ha per year for St. Albert

• Recommended rate of synthetic fertilizer N for forage barley is 45 to 148 kg N ha-1 for irrigated soil and 45 to 113 kg N ha-1 for non-irrigated Black soil

• Surface applied without incorporation (no-till soil conservation practice)

• Manually raked soil surface to mix with top 2-5 cm soil

• Seeded on same day or one day after amendment application

10

Materials and methods

• Duration: four years (2008-2011 for Lethbridge, 2009-

2012 for St. Albert),

• Residual year in 2012 for Lethbridge

• Barley grown and harvested at the soft dough stage as

forage for making silage feed

• AC Metcalf 2-row barley for 2008 to 2010, and Chigwell

2-row barley for 2011 and 2012.

11

Measurements

• Yield, TN, TP and other macro (K, Ca and Mg) and

micro-nutrients (Cu and Zn) contents

• Soil physical and chemical properties after four years

• GHG emission during the growing season over four

years

Cattle manure Separated solids Pellets 1 Pellets 2

Application of amendment

14

Results

Site Soil Depth OM OC TN TP NH4-N NO3-N Olsen-P

cm % % % % mg/kg mg/kg

mg/kg

Leth. D. Brown 0-5 4.5 2.60 0246 0.056 11 32 20

Irrigated 5-15 3.2 1.87 0.192 0.049 8 21 11

15-30 2.2 1.30 0.141 0.047 5 20 6

30-60 20

60-90 18

St. Al. Black 0-5 15.0 8.69 0.886 0.130 15 41 51

Rain-fed 5-15 13.1 7.60 0.756 0.120 10 26 32

15-30 4.2 2.69 0.246 0.048 3 7 3

30-60 3

60-90 2

Initial soil conditions

Green color indicate a higher NO3 content than typically observed in soil

15

Weather conditions

Site Temperature Precipitation

Seeding date Annual June-Sept Annual June-Oct

Leth. 2008 June 17 6.2 16.0 522 300

2009 June 4 5.8 16.6 417 207

2010 June 29 6.3 15.5 607 273

2011 July 7 6.1 17.0 537 189

2012 May 9 7.1 17.5 422 168

Long-term 5.4 15.7 405 200

St. Al. 2009 June 19 1.8 14.9 231 129

2010 June 9 4.2 14.7 441 258

2011 June 2 2.8 14.6 345 257

2012 May 31 3.3 15.8 349 233

Long-term 3.1 14.3 466 304

Green color indicates a higher and red color lower than the long-term average

Lethbridge barley forage yield

† PE and PE2 received pellet application in 2010, other years same as SS and SS2

0

2

4

6

8

10

12

14

16

2008 2009 2010 2011 2012

(a) 1 X rate

CK

M

D

SS

PE

2008 2009 2010 2011 2012

(b) 2 X rate

CK

M2

D2

SS2

PE2

Met

ric

t/h

a

Year Julian date T ppt

°C mm

2008.6.17 169 6.2 300

2009.6.04 155 5.8 207

2010.6.29 180 6.3 273

2011.7.07 188 6.1 189

2012.5.09 131 7.1 168

Long-term 5.4 200

Yie

ld (

kg h

a-1)

Julia date

St. Albert barley forage yield

PE and PE2 received no pellets in 2009

0

2

4

6

8

10

12

14

16

2009 2010 2011 2012

(a) 1 X rate CK M D SS PE

2009 2010 2011 2012

(a) 2 X rate CK M2 D2 SS2 PE2

Yield difference compared to fresh manure at Lethbridge M

etri

c t/

ha

-2

0

2

4

6

2008 2009 2010 2011 2012 Avg

(a) 1 X rate

D-M

SS-M

PE-M

2008 2009 2010 2011 2012 Avg

(b) 2 X rate

D-M

SS-M

PE-M

Yield difference compared to fresh manure at St. Albert M

etri

c t/

ha

2009 2010 2011 2012 Avg

(b) 2 X rate

D-M

SS-M

PE-M

-2

0

2

4

6

8

2009 2010 2011 2012 Avg

(a) 1 X rate

D-M

SS-M

PE-M

Lethbridge barley forage N uptake – kg N / ha

There were no pellets for 2008, 2009 and 2011

0

50

100

150

200

250

2008 2009 2010 2011 2012 Avg

(a) 1 X rate CK M D SS PE

2008 2009 2010 2011 2012 Avg

(b) 2 X rate CK

M2

D2

SS2

PE2

St. Albert barley forage N uptake

There were no pellets in 2009

N u

pta

ke k

g N

/ h

a

0

50

100

150

200

250

300

350

2009 2010 2011 2012 Avg.

(a) 1 X rate

CK M D SS PE

2009 2010 2011 2012 Avg.

(b) 2 X rate CK M2 D2 SS2 PE2

Simplified nutrient flow

from fresh manure to digestate and separated solids

40 t Manure

60% water

40% solid

DM = 8 t Org N = 176 kg Total P = 156 kg

Water = 24 t

Water N = 43 kg

Water P = 14 kg

DM = 8 t

Org N = 176 kg

Total P = 56 kg

Digestion

50% C →CH4

Water = 92 t

Water N = 219 kg

Water P = 70 kg

92% water

8% solid

60% water

40% solid DM = 8 t

Org N = 176 kg

Total P = 56 kg

Water = 12 t

Water N = 27 kg

Water P = 9 kg

Solid-liquid separation

Screw press

100 t Digestate

20 t Separate solid

Fresh manure

• 60% moisture

• TN content = 2.2% (DM)

• TP content = 0.7% (DM)

• Water N = 2.7 g/kg (DM)

• Water P = 0.9 g/kg (DM)

Water N = 192 kg

Water P = 61 kg

80 t Separate liquid

100% water

DM = 8 t Org N = 176 kg Total P = 156 kg

Amendment comparison (same amount of dry matter)

M D* SS PE

Wet weight, tonne 20 100 (50) 20 12

DM (tonne) 8 8 (4) 8 8

Water, tonne 12 92 (46) 12 4

Organic N, kg 176 176 (88) 176 176

Total P, kg 56 56 (28) 56 56

Water N, kg 22 219 (109) 27 10

Water P, kg 7 70 (35) 9 9

*Red font numbers inside bracket indicate actual amount of digestate

applied relative to other amendments

0

10

20

30

40

2008 2009 2010 2011 2012 Avg

(a) 1x rate CK M D SS PE

2008 2009 2010 2011 2012 Avg

(b) 2x rate CK M2 D2 SS2 PE2

Lethbridge barley forage P uptake – kg P / ha

St. Albert barley forage P uptake – kg P / ha

0

10

20

30

40

2009 2010 2011 2012 Avg

(a) 1x rate

CK

M

D

SS

PE

0

10

20

30

40

2009 2010 2011 2012 Avg

(b) 2x rate CK

M2

D2

SS2

PE2

Ca/P ratio in Lethbridge barley forage

• Optimum Ca/P ratio is 1.5 to 2

• > Ca/P < 1 could cause hyperparathyroidism in cattle and decreased milk

production and fertility (Smart and Cymbaluk 1997).

0

2

4

6

8

2008 2009 2010 2011 2012 Avg.

(a) 1x rate CK M D SS PE

0

2

4

6

8

2008 2009 2010 2011 2012 Avg.

(b) 2xr ate CK M2 D2 SS2 PE2

0

2

4

6

8

2009 2010 2011 2012 Avg.

(b) 2x rate CK

M2

D2

SS2

PE2

Ca/P ratio in St. Albert barley forage

• Optimum Ca/P ratio is 1.5 to 2

• > Ca/P < 1 could cause hyperparathyroidism in cattle and decreased milk

production and fertility (Smart and Cymbaluk 1997).

0

2

4

6

8

2009 2010 2011 2012 Avg.

(a) 1x rate CK

M

D

SS

PE

K/(Ca+Mg) ratio in Lethbridge barley forage

0

1

2

3

4

2008 2009 2010 2011 2012 Avg.

(a) 1x rate CK

M

D

SS

PE

0

1

2

3

4

2008 2009 2010 2011 2012 Avg.

(b) 2x rate CK

M2

D2

SS2

PE2

• K/(Ca+Mg) > 2.2 increases occurrence of grass tetany illness in cattle

• No pellets in 2008, 2009 and 2011

0

1

2

3

4

2009 2010 2011 2012 Avg

(b) 2x rate CK

M2

D2

SS2

PE2

K/(Ca+Mg) ratio in St. Albert barley forage

0

1

2

3

4

2009 2010 2011 2012 Avg

(a) 1x rate CK M D SS PE

• K/(Ca+Mg) > 2.2 increases occurrence of grass tetany illness in cattle

• No pellets in 2009

Other consideration

• Type of amendment used had minimum effect on feed

quality in our 5-year study at two Alberta locations

• Other factors

o Crop variety

o Soil type

oWeather condition

o Agronomic practice (seeding date)

• Effective use and cycling of nutrients is critical for

livestock – crop production

• Digestate (liquid form) application seems to produce

highest yields, N and P uptake

• Separated solids performed as well as fresh cattle

manure

• Pellets did not performed as well as fresh manure

• We need to improve our understanding of nutrient

behaviour to ensure long-term sustainability

Summary

Acknowledgements

• The workshop organizers

• Collaborators:

o Alberta Agriculture and Rural Development (ARD)

o University of Manitoba

• Technical staff at AAFC Lethbrige and ARD Ag-Tech Centre

at Lethbridge

• Digestate from Highmark Renewables Inc.

Thank your

Xiying.hao@agr.gc.ca