Safe Use of Animal-based Soil AmendmentsM. Charles Gould

Extension Educator

Agriculture and Agribusiness Institute

Michigan State University Extension

Overview

• Function and purposes of soil amendments

• Types of organic soil amendments• Manure• Biosolids• Compost

Manure pile on a Michigan dairy farm.

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Section 1Function and purposes of soil amendments

What are soil amendments?

• Soil amendments are

organic and inorganic

materials applied on

and mixed into

agricultural soils to

change the physical

and chemical

characteristics of the

soil. Colters slice a furrow into the sod for

liquid manure application.

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Impact of soil amendments in a cropping system• Improve physical properties (texture/tilth/structure)• Improve aeration• Increase water holding capacity (in light soils)

• Increase nutrient-holding capacity• Improve water infiltration (in heavy soils)• Add nutrient/mineral values for plant growth• Improve cation exchange capacity (CEC)• Adjust pH• Suppress soil microbes that could harm plants• Increase the soil microbe community that helps plants

grow.

Environmental and management effects on nutrient release in a cropping system

• Soil moisture

• Soil temperature

• Cover crops

• Soil organic matter

• Crop rotation

• Soil pH

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Grass

cover

crop.

Key point

• Soil amendments are

used in cropping

systems to achieve

specific outcomes.

Oilseed radish cover crop in

Michigan.

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Section 2Types of organic soil amendments: Manure

What is manure?

• The byproduct of the digestive process in ruminant and monogastric animals.

• A common and highly valued soil amendment in a cropping system.

• It can be handled as a solid or a liquid.

Manure total solids characterization and handling requirements. Source: Virginia Cooperative Extension

Benefits of manure

• Supplies macro- and micro-nutrients that are

essential for crop growth.

• Functions like a slow release fertilizer.

• Builds soil organic matter, stimulating the

biological processes in the soil that help to build

fertility.

• Nutrient content varies between species, diet

and bedding content.

Manure handling• Manure storage and treatment sites should be situated

as far as practical from fresh produce production and handling areas.

• Consider barriers or physical containment to secure manure storage or treatment areas where contamination from runoff, leaching, animal, foot and/or equipment traffic, or wind spread is a concern.

• Consider good agricultural practices to minimize leachate from manure storage or treatment areas contaminating produce.

• Consider practices to minimize the potential of recontaminating treated manure.

Manure application• Land application is an

approved method for manure management.

• Generally Accepted Agricultural and Management Practices for Manure Management and Utilization (Manure GAAMPs).

Manure application• A farmer complies with the intent of the Michigan Right

To Farm Act when a Manure Management Systems

Plan is developed, implemented, and sufficient

documentation is provided to prove the plan was

followed.

• Application rate is determined by soil test, amendment

analysis, realistic crop yield, and soil type.

• Manure Management Systems Plans focus more on

nutrient placement and movement rather than pathogen

control.

• Produce Safety Plans focus on pathogen control

Food safety considerations

• Raw manure can never come in contact with the harvestable portion of the crop or harvested produce. (PSR)

• Applications of raw manure should only occur:• Two weeks prior to planting

• A minimum of 120 days prior to harvest for crops in contact with soil.

• A minimum of 90 days prior to harvest for crops not in contact with soil.

• Raw manure must be incorporated within 48 hours of application.

• Raw manure should not be applied on commodities typically eaten raw that are harvested within 120 days of planting.

• Maximize the interval between raw manure application and harvest.

Food safety considerations

• Treatments that may reduce pathogen levels.

• Passive treatment – relies on the passage of time in

conjunction with environmental factors that help reduce

pathogens such as UV, moisture and temperature

fluctuations.

• Active treatments – require more management and inputs.

Includes pasteurization, heat drying, anaerobic digestion,

alkali stabilization, aerobic digestion or some combination.

• Also consider how manure may enter a field from other

sources, and plan accordingly.

• Adjacent field practices can have an affect on your produce

Recordkeeping

• Document what,

where, when, how,

and how much was

applied.

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Tilling surface applied liquid hog

manure into the soil.

Corrective action plan

• What happens when:

• Accidental contact with harvestable portion of the

crop

• Runoff from adjacent fields

• Alternative markets

• Kill step

Key points

• Excellent slow release fertilizer and soil builder.

• Locate manure storage and treatment areas away from fruit and vegetable production areas.

• Land application of manure is an acceptable practice for fruits and vegetables if recommended and Produce Safety Rule practices are followed.

• Manure can be treated to reduce pathogen load.

• Document what, where, when, how and how much manure was applied.

Section 3Types of organic soil amendments: Compost and biosolids

What are biosolids?

• Nutrient-rich organic materials resulting from the

treatment of domestic sewage in a treatment

facility.

• Class A biosolids contain no detectable levels of

pathogens.

• Class B pathogens are treated but still contain

detectable levels of pathogens.

Source: U.S. Environmental Protection Agency

Biosolids storage, handling and application

• Class A biosolids:• Can be applied to fruits

and vegetable crops when following PSR and EPA 40 CFR part 503.

• Are not stored on a farm. Used on demand.

• Are applied by custom applicators.

• Are applied based on a nutrient management plan.

Biosolids are typically granular in

nature.

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Definition of compost

A group of organic residues or a mixture of organic residues and soil that have been piled, moistened, and allowed to undergo aerobic biological decomposition resulting in a dark or black carbon-rich relatively stable humus.

Source: Rynk, R., van de Kamp, M., Willson, G.B., Singley, M.E., Richard, T.L., Kolega, J.J., Gouin, F.R, Laliberty, Jr., L.,

Kay, D., Murphy, D.W., Hoitink, H., and Brinton, W.F. 1992. On-Farm Composting Handbook, Robert Rynk, editor. NRAES-

54. Northeast Regional Agricultural Engineering Service, Cornell University, Ithaca, NY.

Composted manure from an Ottawa County, MI dairy

farm.

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Definition of composting

Composting is controlleddecomposition, the natural breakdown process, of organic residues.

Cooperband, Leslie. 2002. The Art and Science of Composting.

Center for Integrated Agricultural Systems, University of

Wisconsin-Madison, Madison, Wisc.

Rotating

drum

in-vessel

composter

Tractor

pulled

compost

turner

Photo credits: Charles Gould

Constructing Your

Compost Pile

▪ Green materials

▪ Grass clippings

▪ Coffee grounds

▪ Manure

▪ Brown materials

▪ Dried leaves

▪ Chopped straw or hay

▪ Sawdust

▪ Wood shavings

1 part:2-3

parts

Stage 1 of the Compost Process

• Approximately days 1-2.

• Mixed materials are the

same temperature as the

air temperature.

• Psychrophilic bacteria

are active at this stage

(0°- 55°F).

• Heat is produced when

bacteria break down

organic matter.

Stage 2 of the Compost Process

• Approximately days 3-5.

• A well-mixed pile will heat up

to between 100°F and 140°F.

• Mesophilic bacteria, active

between 50°- 120°F, are the

most abundant and do the

most decomposition.

• Oxygen and moisture are

critical at this stage.

Stage 2 of the Compost Process

• Thermophilic bacteria

are active from 110° -

160°F.

• The fastest organic

matter breakdown occurs

during this stage because

of the heat.

• C:N ratio decreases due

to carbon loss.

• pH rises above neutral.

Stage 2 of the Compost Process

• Volume reduction of 50-60%.

• Weight reduction of 40-80%.

• At this stage, pathogens, weed seed, and

fly larvae are destroyed.

• Temperatures above 160°F will cause

microbial activity to cease.

Stage 3 of the Compost Process

• Approximately day 6 and beyond. This stage can last for several weeks or months depending on how often the pile is turned.

• The pile begins to cool down.

• Turning the compost pile can jumpstart Mesophilic bacteria, reheating the pile.

Stage 4 of the Compost Process

• Compost temperature drops to ambient air

temperature.

• “Curing” stage, where chemical reactions

continue to occur that make nutrients in the

compost stable and suitable for plant use.

• This stage can last up to a year.

• Pile can be colonized with actinomycetes,

protozoa, rotifers, nematodes, fungi, and

numerous species of invertebrates.

Compost Management

• Time

• Temperature

• Turning

Summary of Compost Process

• Microbial breakdown of organic matter.

• Reduction in particle size.

• C:N ratio decreases due to carbon

loss.

• pH rises above neutral.

• Volume reduction of 50-60%.

• Weight reduction of 40-80%.

• Static Pile

• Aerated Pile

– Active

– Passive

• Vermicomposting

• In-vessel

• Windrows

– Covered

– Uncovered

• Transfer Bays

– Covered

– Uncovered

Composting Methods

Static Pile

• Leaving raw manure in

a pile for a long period

of time does not yield

compost

• Static piles generally

have odors and flies

• More likely to have

complaints

Aerated Pile – Active or Passive

• Can be a pile or

windrow

• Active Aeration

– Use blower to force air

through pile

• Passive Aeration

– Natural airflow through

vented pipe keeps pile

aerobic

Aerated Pile – Active or Passive

• Covered piles are easier

to control

– Can use a tarp – should

be held above pile

– Can also use peat moss

(6” thick) over pile

– Commercial compost

covers also available

• These allow the pile to

breath but help to control

moisture

Composting Method -Aerated Pile Windrow

Vermicomposting

• Use red worms to “work” manure into compost

• Requires 1 pound of worms per square foot of

windrow surface area

• Yields very high quality compost

• Worms can be sold also

• Must maintain a temperature of 50 deg. F

Turned Windrow

• Can turn by hand – small amounts

• Front loader best option for small farms

• Large turners available

• Covered windrows yield the best compost

Transfer Bays

• Manure or other material is

added to 1 bay then

moved (turned) to other

bays

• 4 – 6 bays are needed

• When manure reaches last

bay it should be finished

compost

When is Compost Ready to Use?

• Compost is ready for use when:

– It smells earthy - not sour, putrid or like

ammonia

– It no longer heats up after being turned

or watered

– It looks like dark soil

– It’s crumbly, and doesn’t have

identifiable items, i.e. manure, wood

shavings, leaves, etc.

– The pH is usually around 7.5, and it will

have a C:N ratio ranging from 10:1 to

20:1.

– It has a moisture content like a damp

sponge.

Soil Amendment – Compost

• Composting livestock manure reduces many of

the drawbacks associated with raw manure use.

• The quality of compost depends on the

feedstocks used to make it.

• The value of compost lies in it’s biology.

• Composting will not eliminate heavy metals.

Compost handling and application

• Application rates are

determined based on

crop yields, compost

analysis, and soil test

results.

• Calibrate spreader

before applying

compost. Spreaders with vertical discharge

beaters easily apply heavy and

dense amendments like compost.

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Compost handling and application

• Minimize the

potential of re-

contaminating

compost through

barriers, containment

or coverage.

Composting site under roof at the

Michigan State University Swine

Teaching and Research Center.

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Food safety considerations

• There is no time interval recommended between

compost application and crop harvest due to the

reduction in pathogens by the high temperature

phase of composting.

• If there are any doubts about the compost, treat

it like raw manure.

Food Safety Considerations cont.• Compost must maintain a

temperature of between 131 and 170°F for:

• 3 days (enclosed system) or;

• 15 days (windrow system),

• during which period the composting materials must be turned a minimum of five times.

• The compost pile should then be cured for 45 days.

• Finished and curing compost piles should be covered in order to prevent recontamination.

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In-vessel

composter

on a pullet

farm

(enclosed

system)

Turning a

windrow of

dairy

manure

compost

(windrow

system)

Pathogen kill during the composting process

• Pathogen kill is a function of temperature and time.

• Common pathogens killed in this phase are Escherichia coli, Staphylococcus aureus, Bacillus subtillus, and Clostridium botulinum. Compost thermometer reading 144

degrees Fahrenheit.

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Food safety considerations cont.

• Tools and equipment should be cleaned and

sanitized if going between composting and

produce use.

• Develop SOP’s

• Direct foot and animal traffic around storage

area

Recordkeeping• Recordkeeping is an

important component a food safety program. Document the following:

• Type of soil amendment being applied

• Composting method and microbial testing (if applicable)

• Fields receiving application

• Date of application

• Rate (quantity applied per acre)

• Method of application

• What crops will be planted

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Compost made from crabs from

the Chesapeake Bay.

Recordkeeping for Food Safety

• Time, temperature, turnings, and any other

processing step(s)

• Third party documentation that composting was

completed in a scientifically valid process.

Key points

• Biosolids and compost increase soil organic matter and are sources of plant nutrients.

• Class A & B biosolids can be used on fruits and vegetables according to EPA and State laws.

• Compost must be managed to kill pathogens.

• Time intervals do not apply to compost that meets temperature and time standards. If there are doubts, treat it like raw manure.

• There is demand for compost in Michigan!

Contact information