The Effect of Compost Application and Plowing on

Phosphorus RunoffCharles S. Wortmann

Department of Agronomy and HorticultureNutrient Management for Soil Productivity

and Water Quality Protection

Phosphorus in fresh surface waters

P is often most limiting nutrient to the growth of aquatic vegetation

Agricultural land is a major source of P♦ Greater losses with high soil test P, e.g.

where much manure has been applied♦ Manure P excretion is increasing as diet P

increases due to feeding by-products

Several field factors affect P loss♦ Site factors, e.g. soil test P and P application♦ Transport factors, e.g., erosion and runoff

Relative importance of total P vs. dissolved P entering waters♦ Aquatic vegetation uses dissolved P♦ Much runoff P is not dissolved P, but may

become available with time♦ Need to be concerned about total P loss

Phosphorus in fresh surface waters

Research at the UNL – ARDC

1998 - 2006

Objectives

Determine the effects on management practices on runoff, sediment loss, and P loss

During the years of application, 1999-2001 The residual effects during 2001 to 2004 Residual effects during 2004 to 05 and

effect of plowing extremely high P soil Residual effects of 2006-07 and effects of

vegetative barriers

Effects during the years of application

Composted feedlot manure was applied annually for 3 years to meet the N need of irrigated corn

Two compost types were used♦ Low P compost: 670 lb/A P applied ♦ High P compost: 1025 lb/A P applied

The plots were disked

Compost effect on soil test P (Bray-P1)

Depth, inches

Hi-P compost

Lo-P compost

No compost

0-2 779 380 16

2-4 307 154 9

4-8 53 37 10

8-12 38 26 10

Results: Runoff and erosion, 99-01 Runoff volume and sediment loss were greatly reduced by compost application during the years of application.

Volume of runoff during 1999 to 2001

0

0.5

1

1.5

2

2.5

3

3.5

Compostapplied

Nocompost

Low-Pcompost

High-Pcompost

Ru

no

ff, a

cre

-in

ch

es

Sediment loss during 1999 to 2001

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Compostapplied

Nocompost

Low-Pcompost

High-Pcompost

Se

dim

en

t lo

ss

, t/A

Runoff and erosion: 01-04

The residual effect of compost applied 1-3 yr previously was reduced runoff and sediment loss.

Residual effect on runoff loss

0

0.5

1

1.5

2

2.5

3

3.5

Low Pcompost

High Pcompost

No compost

Ru

no

ff, A

cre

-in

ch

es

Residual effect on sediment loss

0

0.05

0.1

0.15

0.2

0.25

0.3

Low Pcompost

High Pcompost

No compost

Se

dim

en

t lo

ss

, T/A

c

Runoff and erosion: 04-05

The residual effect of compost at 4 – 5 yr after application♦ Slightly reduced runoff♦ Greatly reduced erosion

The effect of plowing♦ Reduced runoff♦ Slight increase in

sediment loss

Runoff volume

0

0.2

0.4

0.6

0.8

1

1.2

No compostapplied

Compostapplied

Compostapplied,plowed

Ru

no

ff, a

cre-

inch

Sediment loss

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

No compostapplied

Compostapplied

Compostapplied, plowed

Sed

imen

t lo

ss, t

/acr

e

P loss during years of application: ‘99-01

Compost application

1. P concentration in runoff much higher.

2. P loss was increased.

Bio-available P concentration, 1999-2001

0

0.5

1

1.5

2

2.5

Compostapplied

Nocompost

Low-Pcompost

High-Pcompost

P c

on

cen

trat

ion

, pp

m

Bio-available P (FeO test) loss

0

0.5

1

1.5

2

2.5

3

3.5

Compostapplied

Nocompost

Low-Pcompost

High-Pcompost

Ava

ilab

le P

loss

, lb

/A

01-04. Runoff P concentrations were very high 1-3 yr following compost application.

0

2

4

6

8

10

12

High Pcompost

Low Pcompost

Control

Ru

no

ff P

co

nc

en

tra

tio

n, p

pm

Dissolved P

Total P

01-04. Runoff P concentrations were very high 1-3 yr following compost application.0

2

4

6

8

10

12

High Pcompost

Low Pcompost

Control

Ru

no

ff P

co

nc

en

tra

tio

n, p

pm

Dissolved P

Total P

0

1

2

3

4

5

High Pcompost

Low Pcompost

Control

P lo

ss

, lb

/ac

re

Dissolved P

Total P

Runoff P loss was greater with compost applied, but not so much given the difference in soil test P.

2004-05

Soil P levels remained very high where compost had been applied 4 years before

Plowing greatly reduced P at the soil surface.

0

2

4

6

8

10

12

0 400 800 1200 1600

Total soil P, ppm

Soil

dept

h, in

ch

02468

1012

0 100 200 300 400 500

Bray-P1, ppm

Soil

dept

h, in

ch

No compost

Compost

Compost-plowed

2004-05 P loss The residual effect of

compost at 4 – 5 yr after application♦ Much more dissolved

P loss♦ About 100% more

total P loss

The effect of plowing♦ Greatly reduced

dissolved and total P loss

0

0.4

0.8

1.2

1.6

2

No compostapplied

Compostapplied

Compostapplied,plowed

P lo

ss, l

b/a

cre Dissolved P

Total P

Phase IV, 2006-2007

Continued study of residual effects

Vegetative filter strips occupying 1 or 4% of the plot area

Summary

Effects of composted manure application persisted during, and for 5 years after, application♦ Greatly increased soil test P♦ Increased runoff P concentration♦ Reduced volume of runoff and erosion♦ Increased runoff P loss

Summary

Runoff P loss was more affected by change in erosion and runoff rates compared to soil test P

Excessive amounts of P can be applied with little loss if there is little erosion and runoff.

Summary

Plowing soil with excessively high surface P reduced♦ runoff with no increase in erosion♦ P concentration in runoff, and♦ P loss.♦ However, erosion needs to be prevented.

Well-placed vegetative filter strips occupying 1% of the land area are reducing runoff and P loss

P index development

A comparison of 5 PIs from the Midwest.

Differences evaluated considering research results

J. Soil Water Conserv. Developed P index for

Nebraska together with NRCS

Site/management factors

Soil P levels  P application practices:

time, rate and method of application

Management practices such as tillage, cover crops, conservation practices, etc.

Transport factors Runoff Erosion: rainfall,

snowmelt and irrigation  

Distance from center of ‘field’ to a stream, water body, etc.

•Erosion > runoff >> soil test P >Erosion > runoff >> soil test P > distance to water body if within 300 ft > P application practice

Results from Nebraska P Index: scores and ratings

Erosion

rate, t/A

Soil Bray-1 P, ppm

20 100 250 500

2 0.7, L 1.2, L 2.1, M 3.7, M

Results from Nebraska P Index: scores and ratings

Erosion

rate, t/A

Soil Bray-1 P, ppm

20 100 250 500

2 0.7, L 1.2, L 2.1, M 3.7, M

8 2.4, M 3.7, M 6.0, H 10.1, H

Results from Nebraska P Index: scores and ratings

Erosion

rate, t/A

Soil Bray-1 P, ppm

20 100 250 500

2 0.7, L 1.2, L 2.1, M 3.7, M

8 2.4, M 3.7, M 6.0, H 10.1, H

16 4.7, M 7.0, H 11.3, H 18.4, VH

Erosion calculatorErosion (t/ac) = 12.5* LU * CP * ((K–

0.32)*0.5+0.32)/.32 * SF * R/135 * T * I

•LU = Land use

•CP = Conservation practice

•K = Soil erodibility

•SF = Intermediate slope factor

•R = County rainfall factor

•T = Tillage factor

•I = Irrigation

y = 1.13x + 0.38

R2 = 0.89

0

5

10

15

20

0 5 10 15 20

RUSLE2

Ero

sio

n E

sti

ma

tor

Reducing Risk of Phosphorus Pollution of Surface Waters in Crop-Ethanol-Livestock Ecosystems of the Midwest

C. Wortmann (cwortmann2@unl.edu), C. Shapiro, D. Tarkalson, Dept. Agronomy & HorticultureH. Nourdenni, Chemical Engineering G. Erickson, Animal ScienceT. Franti, D. Schulte, Bio-systems EngineeringD. Jose, Agricultural EconomicsK. Brunkhorst, Nebr. Corn Board

USDA-CSRESS Managed Ecosystems/Nebraska Corn Board

P reduction project: feeding beef a ration of 40% bi-products results in 100% more P excretion

(and >75% more NH3 volatilization)

P removal from ethanol stream

Composting vs. stock-piling feedlot manure

Development of decision guide

Research on bulk reduction and N loss with composting

Effect of vegetative buffers on P runoff

Setback distance ….

Effect of non-application (setback) distance to concentrated water flow.

Watersheds: GIS and stakeholders Linking GIS, watershed

model, and index tools with local knowledge♦ Develop BMP targeting

criteria for producers/ advisors for pollutants

♦ GIS linked with simple tools (e.g. RUSLE1, modified P index) for use at field level with producers/stakeholders

Heartland Regional Water

Use

Our Heartland approach Focus areas

♦ 2004 P management♦ 2005: N management♦ 2006: Pesticide

management♦ 2007: Targeting the

application of BMPs in landscapes

Activities♦ Regional research

roundtable♦ Regional training

workshop♦ Develop or enhance

extension resources Extension circulars Web site On-line lessons In-state training

activities

Heartland ….

2007 Heartland NPM Workshop

Targeting the application of BMPs in landscapes

June 5-7 in Nebraska City

http://websoilsurvey.nrcs.usda.gov

http://websoilsurvey.nrcs.usda.gov