Composting

and

Compost

Utilizatio

n

Andy BaryWSU PuyallupOct 3, 2002

Composting

Decomposition of organic materials by aerobic

microorganisms under controlled conditions

1.Compost good soil conditioner2.Improved manure handling3.Improved land application4.Lower risk of pollution5.Pathogen destruction6.Nutrient management7.Disease suppression8.Saleable product???9.Tipping fees

Why compost

Compost Draw backs

1.Time and money2.Lack of equipment3.Land4.Odor5.Weather6.Materials7.N loss8.Farm operation

Analyze Markets

AcquireFeedstocks

Prepare Materialsort, grind, chip, mix,

shred

Bulking Agents

AmendmentsDetermine

Recipe

Active Composting

Low Tech High TechCuring

Time

Screening

Compost Quality

Assessment

“overs”

Product Refinement& Marketing

Blending

Additives

Bagging

Storage

Composting Process Flow Chart

Adapted with permission from the On-Farm Composting Handbook.

Factors that affect composting

OxygenC:N ratioMoisturePorosity, structure, particle sizepHTemperatureTime

Preferred ranges

C:N ratio 20-40:1 25-30:1H2O content 40-65% 50-60%O2 >5% >5%Particle size 1/8-1/2in. variespH 5.5-6.5 6.5-8.0Temperature 110-150F 130-140

Reasonable ranges

Carbon:Nitrogen Ratio

Compost 15-25:1Grass clippings15:1

Biosolids 5:1Food wastes 15:1Dairy manure 20:1Leaves and foliage 60:1Straw 80:1Bark 115:1Paper 170:1Wood or sawdust 500:1

Composting methods

In vesselAerated static pilePassively aerated systems

windrowbunker

Composting methods

In vesselAerated static pilePassively aerated systems

windrowbunker

Composting methods

In vesselAerated static pilePassively aerated systems

windrowbunker

What can I compost?

Animal manuresStraw, hayVegetable matterYard debrisWood shaving/chipsNewspaperFruit and vegetable wastesFish processing wastes

Organic Production Manures

1. Raw manure OK if crop is not for human consumption

2. Incorporated >120 days before harvest if edible is in direct contact with soil or soil particles

3. Incorporated >90 days before harvest if edible is not direct contact with soil or soil particles

Organic Production Compost non animal

materials

Plant residues, etc

No specific composting regulations

Organic Production Compost animal materials

1. Initial C:N 25:1 – 40:12. Meet PFRP3. In vessel or covered 131-170oF, 3 days,

All portion of pile meets this temperature.4. Turned windrow 131-170oF, minimum 15

days with 5 turns.

Soil fertility and nutrient management

Nutrient Management•Meet crop nutrient needs

•Maintain soil quality

•Conserve resources

•Protect water quality -- reduce leaching and runoff risk

Plant NutrientsMajor Nutrients•Nitrogen

•Phosphorus

•Potassium

•Calcium

•Magnesium

•Sulfur

Micronutrients•Boron

•Iron

•Manganese

•Zinc

•Copper

•Chloride

•Molybdenum

How nutrients become available

Mineral Matter Organic Matter

KMgCa

N

SP

K+ NH4+ Ca++ SO4--

soluble, available

Notavailable

-

-

- -

-

-- - - - -

Ca++ K+

clay OM

- - --

- -

Mg++

K+

Nutrient Anion Availability

Anion Binding SolubilityPO4

-3 strong low

BO3-3 medium medium

SO4-2 v. weak high

NO3- v. weak v. high

Organic N

NH4+

NO3 -

Leaching Gases

Plants,Microbes

Plant residues,Manure

Nitrogen Cycle

Organic Materials

•Little or no processing

•Low nutrient content

•Slow release of nutrients

•Plant, animal, or mineral sources

Processed Manures

Heated >150oF for 1 hour

and less than 12%

moisture

Organic Materials:Slow release nutrients

•Plants can only take up nutrients that are in available form (simple, soluble ions).

•Most nutrients in organic materials are in complex organic molecules or minerals, and are not immediately available to plants.

Slow release nutrients

•Biological processes slowly release the nutrients in organic amendment into available forms.

•Rate of nutrient release depends on the nature of the amendment and environmental conditions.

Nutrient uptake

•The forms of nutrients taken up by plants are the same for all types of fertilizer -- manufactured or organic.

Organic materials:Fertilizers vs. Soil

amendments

•Fertilizer 1. High nutrient content and availability.

2. Main benefit is nutrients. 3. Relatively small amounts applied.

•Soil amendment 1. Low nutrient content and availability. 2. Main benefit is organic matter. 3. Large amounts applied.

Carbon:Nitrogen ratio

•Low C:N supplies N to plants

•High C:N ties up N by biological immobilization

C:N ratio and N availability

C:N

<10:1

10:1 to 20:1

20:1 to 30:1

>30:1

N availability

High

Med - Low

Very Low

Negative

High N ContentC:N < 10:1

•Rapid N availability

•Use as a fertilizer

•Over application leads to excess nutrient levels in soil -- potentially harming crop and water quality.

High N ContentExamples

•Poultry manure

•Packaged organic fertilizers

•Fresh dairy or goat manure

Moderate N ContentC:N 12:1 to 25:1

•Slow N availability

•Can add large amounts without risk of over-fertilization

•Use as a soil amendment

•Expect some N immobilization (tie-up) shortly after application.

Moderate N ContentExamples

•Compost

•Yard debris

•Cover crop residues

•Dairy solids

Low N contentC:N > 30:1

•N immobilization

•Need to add N along with organic amendment

•Use as mulch or bulking agent for compost

Low N contentExamples

•Straw

•Sawdust

•Paper waste

Total Soil Carbon (0-3 in)

Year

1994 1995 1998

To

tal C

, per

cen

t

0

1

2

3

4

5FY FYP FW No compost

hort4.jnbDec 23, 99

Happy Composting

Clopyralid in Compost

What’s the story?

N

Cl

Cl

COOH

Clopyralid•What is it? A herbicide that kills many broad-leaved weeds.

It is used on lawns, hay crops, wheat, and

some other crops

Legumes, nightshades, and composites are the most susceptible families.

Clopyralid•How does it get into compost? Applied to lawns by lawn care companies

Clippings recycled as yard debris become

feedstock for compost.

Breakdown of clopyralid in compost is slow.

Clopyralid•Other sources of contaminationManure from horses fed grass hay treated with clopyralid

Straw from grain crops treated with clopyralid

Clopyralid•Will contaminated compost kill my plants? No. But, there may be symptoms of damage on some susceptible garden plants, such as peas, beans, potatoes, and tomatoes. Most plants are unaffected by clopyralid.

Peas, beans and marigolds grown in 3:1 v/vcompost:perlite mix Peas and beansshow symptoms, marigoldsshow no symptoms.

Leaf from tomato plantgrown inunamended soil.

Leaf from tomato plant grown in soilamended with 50% compost.