Farm-System Modeling to Evaluate Environmental Losses and

Management Practice Cost-Effectiveness

Andy McLean, Tamie Veith, Al Rotz, Jim Hamlett, Jim Shortle

USDA-ARS Pasture Systems and Watershed Management Research

Unit & The Pennsylvania State University

Loadings to the Chesapeake Bay

Agriculture dominates all other sectors for

nutrient and sediment contributions57

%

45%

70%Legend

AgriculturePoint SourceForestDeveloped

Study Region

Chesapeake Bay

Susquehanna River

Dauphin County

Lebanon County

Lancaster County

Most Beneficial Practices as Determined by Regional

StudiesRank Lancaster County

Informal Study (2004)

CBC (2004) Cost-effective strategies for the Bay

1 Nutrient management plan

Wastewater Treatment Plant Upgrades

2 Cover crops Diet and Feed Adjustments

3 Management advice Traditional Nutrient Management

4 Structural field practices Enhanced Nutrient Management

5 Conservation tillage Conservation Tillage

6 Implement farm conservation plan

Cover Crops

7 Cultural field practices (crop rotation, etc.)

8 Develop farm conservation plan

9 Grass buffers, 15-ft  

10 Animal waste system  

Objective

Simulate representative farming systems for this region to determine the environmental benefit of

management practices and determine their economic

value to the producer

Baseline Descriptions

Crop FarmOld Order

Amish DairyContemporary

Dairy

400 ha (1000 ac)4 yr rotationC-SB-C-SB/WW

Primarily no-till Import poultry manure & some starter fertilizer

100 cows120 ha (300 ac)8 yr rotation

2(Cg)-2(Cs/WW)-4(Hay)Primarily no-tillLow grain to forage50% rented fields

50 cows24 ha (60 ac)8 yr rotation4(Cs/WW)-

4(Alfalfa)Conventional-tillHigh grain to forage

Horse-drawn methods

Practices InvestigatedFarm Management Cropping Strategies

Nutrient ManagementTreatment Strategies

Tillage (conv., mulch, no)Strip croppingManure storage (4, 6, 12 month)

Manure reallocation among cropsManure application (broadcast, immediate incorp.)

Field-edge grass buffer

Crop conversion(50% silage to grazed pasture)

Cover Crop (mulch winter grain)

Double Crop(harvest winter grain)

Dietary P (100%, 120% of NRC)

Dietary N (100%, 110% of NRC)

Tests against prior methods

Integrated Farm System Model (IFSM)

Soil

Establish

Crop

Harvest

Storage

Animal

Manure

Grazing

Volatile lossExported manure

Purchased feed,bedding, etc.

Feed soldVolatile loss

Fixed nutrients

Volatile loss

Purchased fertilizer

Runoff & Leaching loss

Milk and animals

Engine exhaust

Challenges of Modeling an Amish Dairy Farm

Machinery Differences Machine specifications Operational efficiency Power requirements Costs Horses vs. Tractors

Corn Harvest

Challenges of Modeling an Amish Dairy Farm

Operational Differences Labor requirements Timing of operations Representing horses

BASELINE RESULTS

Yield Comparison (t DM/ha)

 IFSM Crop

IFSM Cont. Dairy

NASSDistrictCons.

Corn grain

8.7 (2.0)7.8

(1.6)5.9 – 7.9 8.5

Corn silage

— 16 (2.3) 16 16 – 21

Soybeans 2.8 (0.3) — 2.2 – 2.7 2.9

Small grain

4.2 (0.4)1.8

(0.2)3.0 – 3.9 5.2

Alfalfa — 9.4 7.711 – 13.5

Operational Timing (day of year)

IFSM Crop

IFSM Cont. Dairy

District Cons.

Corn plant 129 116 110

Corn harvest 284-289 247-286 283

Wheat plant 297 309 293

Wheat harvest 183-184 118-116 176-186Soybean plant 133 130Soybean harvest

289-294 288-298

Hay harvest4

cuttings3-5

cuttings

Amish DairyLabor Requirements (hour)

IFSM Total Labor

Extension Estimate

Corn planting 65 99

Hay harvest 71 60Corn silage harvest

335 270

Small grain planting

55 40

Manure handling 349 360

Avg. Nutrient Loss (kg/ha-yr)

IFSMCrop

IFSM Contemp. Dairy

IFSM AmishDairy

Chesapeake

modelN volatilized

10.4 69.2 122.7

N leaching 29.7 20.8 44.8

N denitrified

16 14.5 35.3

P runoff (sed+sol)

1.2 0.4 1.7 0.19-0.84

P buildup 8.9 -4.6 28.2

Erosion 2132 294 23811424-2376

MANAGEMENT PRACTICE PERFORMANCE

-100

-50

0

50

100

150

200

250

300

Perc

en

t C

han

ge

Mulch

Till

-50

0

50

100

150

200

Perc

en

t C

han

ge

Mulch Till

Man.

Inco

rp.

No-till

Conv

Till

Strip

Crop DC

Man.

Inco

rp.

DC +

NM100%

CCDC +

NM

100%

CCCCNo-ti

ll

Phosphorus Runoff Sediment Runoff

Conv

Till

Crop Farm

-25

-20

-15

-10

-5

0

5

10

15

20

25

Perc

en

t C

han

ge

-40

-20

0

20

40

60

80

100

120

140

Perc

en

t C

han

ge

Nitrogen Leaching

100%

CC

NM

DC

CCDC

+

NM

DC

CCNM

Con

v Ti

ll

Grass

Buffer

Return to Management

DC

+

NM

Crop Farm

-50

0

50

100

150

200

250

300

350

400

Perc

en

t C

han

ge

4 mo st

or.

+ Man.

Inco

rp.

-50

0

50

100

150

200

250

300

350

400

450

Perc

en

t C

han

ge

Phosphorus Runoff Sediment Runoff

Mulch Till

Man.

Inco

rp.

Strip

Crop

Conv

Till

4 mo st

or.

+ Man.

Inco

rp.

Strip

Crop

DCCCGra

ss

Buffer

Mulch Till

Man.

Inco

rp.

Conv

Till

Contemporary Dairy

-50

0

50

Perc

en

t C

han

ge

-10

0

10

20

Perc

en

t C

han

ge

DC

Nitrogen Volatilization Nitrogen Leaching

12 mo

stor

.

Man

. Inco

rp.

High N

diet

12 mo

stor

.

CC

High N

diet

CCDC

4 mo

stor

. NM

Contemporary Dairy

-15

-10

-5

0

5

10

15

20

Perc

en

t C

han

ge

Return to Management

NM

4 mo st

or.

Grass

buffer 4 mo st

or.

+ Man.

Inco

rp.

DCConv.

Till

Contemporary Dairy

-100

-75

-50

-25

0

25

Perc

en

t C

han

ge

-75

-50

-25

0

25

Perc

en

t C

han

ge

Phosphorus Runoff Sediment Runoff

High

P Diet

No-tillMulch

Till

Convert

to

pasture

DC +

NM

Convert

to

pasture

DCDC

Mulch

Till

No-till

Strip

CropStri

p

Crop

Amish Dairy

-50

-25

0

25

Perc

en

t C

han

ge

-5

0

5

10

15

20

Perc

en

t C

han

ge

Nitrogen Volatilization Nitrogen Leaching

DC +

NM

Conve

rt

to p

astu

re

6

mo

stor

.

4 mo

stor

. +

Man

.

Inco

rp.

NM

DC

4

mo

stor

.

High N

diet

Conve

rt

to

pastu

re

High

N

diet

4 mo

stor

.

6 mo

stor

.

DC

+

NM

Amish Dairy

-100

-75

-50

-25

0

25

Perc

en

t C

han

ge

Return to Management

No-till

4 mo

stor.

Convert

to

pasture

6 mo

stor.

DCDC

+NM

4mo st

or. +

Man. Inco

rp.

Amish Dairy

Amish Dairy• No-till• Pasturing• Strip cropping• Cover cropping

(baseline)

Contemporary Dairy

• Cover cropping• Nutrient

management• Strip cropping• No-till (baseline)

Crop Farm• Cover cropping• Double cropping• No-till • Strip cropping • Grass buffer

Best environmental practices for each farm?

Most profitable management practices for each farm

Amish Dairy Farm

• Double cropping• Mulch tillage

Contemporary Dairy Farm

• Nutrient management• Reduced manure

storage

Crop Farm• Cover cropping• Double cropping• Nutrient

management• Reduced tillage

Distributions Across 25 Years of Weather

Nitrogen loss

Phosphorus loss

Farm profit

Cost Effectiveness

Phosphorus loss Nitrogen loss

Conclusions Most management practices have a nutrient

tradeoff - at least as they are modeled in this study

Farm operation/strategy/location may have a significant impact on which practices are best

Double cropping shows great potential

Cost-effective reductions from “low-hanging fruit”

Corn appears to be water limited, not nutrient limited, therefore we may be over-applying nutrients to corn

Profitability and the environment benefited from transferring manure nutrients from corn to small grain

Application of Results

Provide a basis for recommendations by conservation district officials and policymakers

Hopefully encourages farmers to experiment with these practices

USDA

Pasture Systems and Watershed Management Research Unit

University Park, Pennsylvania

Agricultural Research Service