nutrient losses from management intensive grazing dairy farms in central maryland ray r. weil and...

NUTRIENT LOSSES FROM MANAGEMENT NUTRIENT LOSSES FROM MANAGEMENT INTENSIVE GRAZING DAIRY FARMSINTENSIVE GRAZING DAIRY FARMS

IN CENTRAL MARYLAND IN CENTRAL MARYLAND

NUTRIENT LOSSES FROM MANAGEMENT NUTRIENT LOSSES FROM MANAGEMENT INTENSIVE GRAZING DAIRY FARMSINTENSIVE GRAZING DAIRY FARMS

IN CENTRAL MARYLAND IN CENTRAL MARYLAND

Ray R. WeilRay R. Weil and and Rachel E. GilkerRachel E. Gilker Dept. of Natural Resource Sciences and Landscape Dept. of Natural Resource Sciences and Landscape

ArchitectureArchitectureUniversity of Maryland, College ParkUniversity of Maryland, College Park

in collaboration within collaboration withBill StoutBill Stout

late, USDA Pasture Lab, PA

Dairy Farming: Changing Feed…Dairy Farming: Changing Feed…

……into Milkinto Milk

Feeding Feeding silagesilage

GrazinGrazing g

Confined Feeding SystemsConfined Feeding Systems

High production per cow and per High production per cow and per

acre.acre. High cost per CWT milk. High cost per CWT milk.

Grow, harvest and transport Grow, harvest and transport crops.crops.

Import feed and fertilizerImport feed and fertilizer Collect, store and haul manureCollect, store and haul manure

Cows standing stillCows standing still

Manure on the move Manure on the move

High capital costsHigh capital costs

Farmland covered in perennial Farmland covered in perennial grass instead of annual crops.grass instead of annual crops.Little erosion or sediment Little erosion or sediment

lossloss Cows managed to ‘harvest’ Cows managed to ‘harvest’

feed and ‘spread’ manure. feed and ‘spread’ manure. Low need for imported feed, Low need for imported feed,

fertilizer, fuel.fertilizer, fuel.

Management Intensive Grazing (MIG) Management Intensive Grazing (MIG)

Seasonal milk productionSeasonal milk production Modest production per cowModest production per cow Much lower cost per CWTMuch lower cost per CWT

Higher profitability.Higher profitability. Less control over manure/urine Less control over manure/urine

distribution?distribution?

Grass stands stillGrass stands still

Cows harvest feedCows harvest feed

Grazers control manure distribution by managing cows, water, fencing, etc.

Grass controls erosion…but does grazing Grass controls erosion…but does grazing cause nutrient pollution?cause nutrient pollution?

70 -85% of N and 70 -85% of N and P ingested P ingested passes thru the passes thru the cow.cow.

500-1000 kg 500-1000 kg N/ha/yr directly N/ha/yr directly under urine and under urine and fecal patches. fecal patches.

Excretions by Excretions by grazing cows grazing cows cover only about cover only about 15% of pasture 15% of pasture surface in any 1 surface in any 1 year.year.

Nutrient Pollution Nutrient Pollution ResearchResearch

Previous research has Previous research has suggested intensive grazing suggested intensive grazing causes high N leaching.causes high N leaching.

NZ and European research NZ and European research used high N fertilization rates used high N fertilization rates (300 - 600 kgN/ha).(300 - 600 kgN/ha).

Monolith lysimeters used in Monolith lysimeters used in some research may cause some research may cause artifact ponding and artifact ponding and preferential flow patterns.preferential flow patterns.

Nutrient Pollution PredictionsNutrient Pollution PredictionsNutrient Pollution PredictionsNutrient Pollution Predictions

From: Stout, W.L., et al. 2000. J. Soil Water Cons.:238-243.

Predicted Mean Annual Ground Water

Nitrate-N (ppm)

Predicted Mean Annual Ground Water

Nitrate-N (ppm)

Cumulative Seasonal Stocking Rates (AUD/ha)Cumulative Seasonal Stocking Rates (AUD/ha)

N fertilizer

White clover

N fertilizer

White clover

Stocking rates on Stocking rates on MIG farms in our MIG farms in our

studystudy

Stocking rates on Stocking rates on MIG farms in our MIG farms in our

studystudy

Urine Urine spots in spots in the fieldthe field

Relative Relative size of size of leaching leaching lysimeterlysimeter

Artifact Artifact ponding and ponding and preferential preferential flow?flow?

Objectives were to… Objectives were to…

monitor monitor nutrient concentrationsnutrient concentrations in in groundwater under 4 MIG and 2 confined-groundwater under 4 MIG and 2 confined-feeding watersheds. feeding watersheds.

estimate estimate nutrient loadingnutrient loading from 1 confined from 1 confined feeding and 2 MIG dairy farms.feeding and 2 MIG dairy farms.

calculate whole farm calculate whole farm nutrient balancesnutrient balances for the 3 farms. for the 3 farms.

determine if determine if organic forms organic forms constitute constitute significantsignificant part ofpart of N and P N and P leaching leaching losses.losses.

Recent studies suggest Recent studies suggest organic forms may be organic forms may be important for N and P losses…important for N and P losses… Currie et al, 1996: Measured DON at 56 & 67% of Currie et al, 1996: Measured DON at 56 & 67% of

total N under pine and hardwood stands. total N under pine and hardwood stands. (MA)(MA)

Smolander et al, 2001: DON was 62-83% of total Smolander et al, 2001: DON was 62-83% of total N in soil solution under spruce stands. N in soil solution under spruce stands. (Norway)(Norway)

Streeter et al, 2003: Streeter et al, 2003: 60% of the N in lakes of agricultural catchments in organic form (UK) (UK)

Willet et al, 2004: DON makes up 40-50% of total Willet et al, 2004: DON makes up 40-50% of total N in streams and lakes, and may be >85% of N in streams and lakes, and may be >85% of TDN. TDN. (Wales)(Wales)

HypothesesHypotheses Average groundwater N and P under MIG will be Average groundwater N and P under MIG will be

≤≤ those under confined feeding.those under confined feeding. Annual average N and P will be below acceptable Annual average N and P will be below acceptable

limits.limits.Nitrate-N: 10 mg/LNitrate-N: 10 mg/L

Dissolved Reactive Phosphate: 0.01 mg/L?Dissolved Reactive Phosphate: 0.01 mg/L?Total P: 0.1 mg/L?Total P: 0.1 mg/L?

Nutrient surpluses lower on the MIG farms than Nutrient surpluses lower on the MIG farms than on the confined feeding farm.on the confined feeding farm.

Significant Significant organicorganic N and P in groundwater under N and P in groundwater under dairy farms.dairy farms.

Three Md. Farms in this Study Three Md. Farms in this Study

9.97.81.5P

1737154NSurplus kg/ha

23 t ha-1 y-1810348AUD2 orManure

6 yr: corn/oats/alfalfa

pasture/ 24% legume

pasture/ 8% legume

Vegetation

2.12.20.95AU1/ha

2457183Farm, ha

ConfinedGrazer2Grazer1

1 AU = one animal unit of 454 kg 2 AUD = annual AU days per ha

Profit: $/CWT: 6.99 4.34 3.60

Methods…Methods… 3 farms, each with 2 3 farms, each with 2

watersheds (A and B).watersheds (A and B). A transect of 3 piezometer A transect of 3 piezometer

nests at outlet of each nests at outlet of each watershed (+ 1 upslope watershed (+ 1 upslope control well on each farm).control well on each farm).

3 or 4 piezometers in each 3 or 4 piezometers in each nest – each 1 m deeper nest – each 1 m deeper than the next.than the next.

5 stations 100 m apart 5 stations 100 m apart along each of two streams along each of two streams on Grazer 2 farm.on Grazer 2 farm.

A nest of three piezometers

Groundwater Monitoring Groundwater Monitoring DesignDesign

Nest ANest ANest BNest B

Nest CNest C

1- 6 ha watershed1- 6 ha watershed

CCCCBBBB

AAAA

Sampling Sampling May 2001-July 2004May 2001-July 2004

Groundwater Groundwater sampled biweekly.sampled biweekly.

Streams on Grazer 2 Streams on Grazer 2 farm sampled farm sampled biweekly + plus biweekly + plus storms.storms.

Confined AConfined A

Grazer 2 AGrazer 2 A

0

10

20

30

40

Nitr

ate-

N,

mg

L-1

0

10

20

30

40

Nitr

ate-

N,

mg

L-1

Nitrate-NWater table

500600

700800

9001000

1100

12001300

14001500

16001700

Day of Century

0

10

20

30

40

Nitr

ate-

N,

mg

L-1

0

10

20

30

40

Nitr

ate-

N,

mg

L-1

0

10

20

30

40

Nitr

ate-

N,

mg

L-1

Nitrate-NWater table

500600

700800

9001000

1100

12001300

14001500

16001700

Day of Century

0

10

20

30

40

Nitr

ate-

N,

mg

L-1

500600

700800

9001000

1100

12001300

14001500

16001700

Day of Century

Grazer 1 A

Soil surface

EPA limit

Grazer 1 B

Grazer 2 A Grazer 2 B

Confined A Confined B

Nitrate - NNitrate - N and

groundwater levels

under six watersheds

Nitrate - NNitrate - N and

groundwater levels

under six watersheds05/01 – 06/0405/01 – 06/04

Water tableWater table

Nitrate-NNitrate-N

Because of drought, only data from 10/02 – 06/04 used for statistical comparisons

Because of drought, only data from 10/02 – 06/04 used for statistical comparisons

Nitrate-N Nitrate-N in groundwater under six watersheds during the study period

1000 1100 1200 1300 1400 1500 1600 1700Day of Century

0

10

20

30

40

50N

i tra t

e N

, m

g/L

Grazer 2Grazer 1Confined

1000 1100 1200 1300 1400 1500 1600 1700Day of Century

0

10

20

30

40

50N

i tra t

e N

, m

g/L


Drought period

(5/01-11/02) excluded

Drought period

(5/01-11/02) excluded

2003 20042002

1000 1100 1200 1300 1400 1500 1600 1700Day of Century

0

10

20

30

40

50N

i tra t

e N

, m

g/L



1000 1100 1200 1300 1400 1500 1600 1700Day of Century

0

10

20

30

40

50N

i tra t

e N

, m

g/L



Distance weighted least squares lines

Distance weighted least squares lines

N=2700

0

5

10

15

20

25

30

35

40N

itrat e

- N, m

g L

-1

Spring Summer Fall WinterSEASON

0

5

10

15

20

25

30

35

40

Nitr

at e

- N, m

g L

-1


0

5

10

15

20

25

30

35

40N

itrat e

- N, m

g L

-1

Spring Summer Fall WinterSEASON

0

5

10

15

20

25

30

35

40

Nitr

at e

- N, m

g L

-1


Annual Annual average average

nitrate –Nnitrate –N

Annual Annual average average

nitrate –Nnitrate –N

20022002

20032003 95%confidenceInterval formean

Box plot

1000 1100 1200 1300 1400 1500 1600 1700Day of Century

0

10

20

30

40

50To

tal D

isso

l ve

d N

, mg

/ L


2002 <------------ 2003 ---------------> <------- 2004 ------>

Groundwater TDNMeans of 2 watershedson each farm

1000 1100 1200 1300 1400 1500 1600 1700Day of Century

0

10

20

30

40

50To

tal D

isso

l ve

d N

, mg

/ L


2002 <------------ 2003 ---------------> <------- 2004 ------>

Groundwater TDNMeans of 2 watershedson each farm

Jan 02 – Mar 04

Jan 02 – Mar 04

Nitrate-NNitrate-N in in three three

piezometer piezometer nestsnests under

six watersheds during the

study period

0

10

20

30

40

Nitr

ate-

N, m

g L

-1

0

10

20

30

40

Nitr

ate-

N, m

g L

-1

ctrlcba

Nest

700800

9001000

1100

12001300

14001500

Day of Century

0

10

20

30

40

Nitr

ate-

N, m

g L

-1

700800

9001000

1100

12001300

14001500

Day of Century




0

10

20

30

40

Nitr

ate-

N, m

g L

-1

0

10

20

30

40

Nitr

ate-

N, m

g L

-1

ctrlcba

Nest

700800

9001000

1100

12001300

14001500

Day of Century

0

10

20

30

40

Nitr

ate-

N, m

g L

-1

700800

9001000

1100

12001300

14001500

Day of Century




Nest aNest aNest bNest b

Nest cNest c

Confined Grazer 1 Grazer 20

3

6

9

12

Nitr

ate

-N,

mg

/L

homesteadaway

Confined Grazer 1 Grazer 20

3

6

9

12

Nitr

ate

-N,

mg

/L

homesteadaway

Confined Grazer 1 Grazer 20.01

0.02

0.03

0.04

0.05

Dis

solv

ed

Org

an

ic P

, mg

/ L

homesteadaway

Confined Grazer 1 Grazer 20.01

0.02

0.03

0.04

0.05

Dis

solv

ed

Org

an

ic P

, mg

/ L

homesteadaway

Nitrate-NNitrate-N Dissolved Organic PDissolved Organic P

Groundwater nutrients by proximity of watershed to barnyard

0

5

10

15

N in

gro

un

dw

ate

r, m

g/ L

DONNO3-N

2002-2003

0

5

10

15

N in

gro

un

dw

ate

r, m

g/ L

DONNO3-N

2002-2003

Dissolved Organic and Inorganic Nitrogen in Groundwater under Six Dairy Watersheds

DON = 20% of Total NDON = 20% of Total N

0.00

0.05

0.10

0.15

0.20

0.25

0.30

Dis

so

lve

d P

, m

g/L Diss Organic P

Diss Reactive P

Dissolved Organic and Inorganic Phosphorus in Groundwater under Six Dairy Watersheds

Org. P varies from 20 to 43% of Total dissolved P

Org. P varies from 20 to 43% of Total dissolved P

Grazer 2 Grazer 2 farm farm located on located on calcareous calcareous parent parent material.material.

Grazer 2 Grazer 2 farm farm located on located on calcareous calcareous parent parent material.material.

Means of 106 to 160 samples

Means of 106 to 160 samples

Stream Water Total NitrogenStream Water Total NitrogenWatershed AWatershed A

1 2 3 4 5SITE

0

1

2

3

4

5

Str

eam

wat

er N

, ppm

DONNO3-N

05/01 - 02/04Storm flow, stream A

Storm FlowStorm Flow

Stream Flow

1 2 3 4 5SITE

0

1

2

3

4

5

Str

ea

m w

ate

r N

, p

pm DON

NO3-N05/01 - 02/04Base flow, stream A

Base FlowBase Flow

Stream Flow

Stream Water Total NitrogenStream Water Total NitrogenWatershed BWatershed B

1 2 3 4 5SITE

0

1

2

3

4

5

Str

eam

wat

er N

, pp

m DONNO3-N

05/01 - 02/04Base flow, stream B

Base FlowBase Flow

Stream Flow

1 2 3 4 5SITE

0

1

2

3

4

5

Str

ea

m w

ate

r N

, pp

m DONNO3-N

05/01 - 02/04Storm flow, stream B

Storm FlowStorm Flow

Stream Flow

1 2 3 4 5CTRL

Sampling station

0.00

0.05

0.10

0.15

0.20

P c

onc.

(m

g /L )

1 2 3 4 5CTRL

Sampling station

Particulate PDiss. Org PDiss. Reactive P

Storm flow8 dates

Base flow23 dates

Storm flowStorm flow Base flowBase flow

Streamwater P across grazed watersheds (means of two

streams)

Flow directionFlow direction Flow directionFlow direction

1 2 3 4 5Sampling site

0.00

0.05

0.10

0.15

0.20

0.25

Tota

l Dis

slo

ved

Ph

osp

ho

rus,

mg

/L

Stream 2, storm flowStream 2, base flowStream 1, storm flowStream 1, base flow


0.00

0.05

0.10

0.15

0.20

0.25

Tota

l Dis

slo

ved

Ph

osp

ho

rus,

mg

/L



0

1

2

3

4

5

Tota

l Dis

s lov

ed N

itrog

en,

mg/

L



0

1

2

3

4

5

Tota

l Dis

s lov

ed N

itrog

en,

mg/

L


Stream Flow Stream Flow

TDNTDNTDPTDP

0

10

20

30

40

50D

issolv

ed n

utr

ient in

org

anic

form

, %

PN

Nutrient

0

10

20

30

40

50D

issolv

ed n

utr

ient in

org

anic

form

, %

PN

Nutrient

Percent of dissolved N and P in organic formsPercent of dissolved N and P in organic forms

Mean annual nutrient losses in groundwater for three dairy farms in Maryland Based on drainage

volumes estimated using WATBALa.

FarmFarm Nitrate-NNitrate-N TDNTDN DRPDRP TDPTDP

------------------ kg ha-1 y-1

----------

Confined feeding farm

24 30 0.50 0.60

MIG Grazer 1 12 14 0.55 0.62

MIG Grazer 2 16 20 0.11 0.26

a Vinten, A.J.A. 1999. Predicting water and chloride transport in drained soils derived from glacial till. J. Environmental Quality 28:980-987.

Relationship Between Nutrient Input-output Surplus and

Estimated Nitrate-N Leaching Loss for Three Maryland Dairy

Farms.

0 25 50 75 100 125 150 175 200

N Surplus (kg ha-1 y-1 )

5

10

15

20

25

30

Nitr

ate

-N lo

ss (

k g h

a- 1 y

- 1)

Confined

Grazed2

Grazed1

2Y = 7.7+0.11*XR =0.91**

Summary for MIG watershedsSummary for MIG watersheds

Annual stocking rates were 348-810 animal days/ha.

Monolith lysimeter research (Stout et al., 2000) predicted annual average NO3-N of 15 and 32 ppm15 and 32 ppm in leachate for these stocking rates.

We found annual average NO3-N of 4 4

and 6 ppmand 6 ppm in shallow groundwater for these stocking rates.

Annual stocking rates were 348-810 animal days/ha.

Monolith lysimeter research (Stout et al., 2000) predicted annual average NO3-N of 15 and 32 ppm15 and 32 ppm in leachate for these stocking rates.

We found annual average NO3-N of 4 4

and 6 ppmand 6 ppm in shallow groundwater for these stocking rates.

1.1. Nitrate-N Nitrate-N averaged averaged 4.4 mg/L.4.4 mg/L.

2.2. Total dissolved N averaged 5.2 Total dissolved N averaged 5.2 mg/L.mg/L.

(of which 20 (of which 20 ± 2± 2% was organic)% was organic)

Total dissolved P averaged Total dissolved P averaged 0.136 mg/L.0.136 mg/L.

(of which 32 (of which 32 ± 1± 1 % was organic) % was organic)

1.1. Nitrate-N Nitrate-N averaged averaged 4.4 mg/L.4.4 mg/L.

2.2. Total dissolved N averaged 5.2 Total dissolved N averaged 5.2 mg/L.mg/L.

(of which 20 (of which 20 ± 2± 2% was organic)% was organic)

Total dissolved P averaged Total dissolved P averaged 0.136 mg/L.0.136 mg/L.

(of which 32 (of which 32 ± 1± 1 % was organic) % was organic)

Summary for MIG Summary for MIG groundwatergroundwater

4. Stream base-flow N and P levels not affected by grazed pastures.

5. Storm flow P in one stream was elevated when passing winter holding area.

6. Nutrient surpluses/ha on grazing farms were lower than on confined farm, even if animal units/acre were equal.

4. Stream base-flow N and P levels not affected by grazed pastures.

5. Storm flow P in one stream was elevated when passing winter holding area.

6. Nutrient surpluses/ha on grazing farms were lower than on confined farm, even if animal units/acre were equal.

Summary for MIG Summary for MIG watershedswatersheds

ConclusionsConclusions

We found N and P leaching under MIG pastures We found N and P leaching under MIG pastures no higher than under manured cropland.no higher than under manured cropland.

N leaching losses were related to surplus in N leaching losses were related to surplus in farm nutrient balance.farm nutrient balance.

MIG appears to have potential as a profitable MIG appears to have potential as a profitable Best Management Practice for environmental Best Management Practice for environmental quality.quality.

Thanks to the NE SARE program of Thanks to the NE SARE program of USDA for funding, and to the three USDA for funding, and to the three farmers for their kind cooperation farmers for their kind cooperation and good stewardship of the land.and good stewardship of the land.

nutrient losses from management intensive grazing dairy farms in central maryland ray r. weil and...

Documents

total n

mig farms

significant organic

annual average n

mig dairy farms

high n fertilization

total p

nutrient losses