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Composting Decomposition of organic materials by aerobic microorganisms under controlled conditions.

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Presentation on theme: "Composting Decomposition of organic materials by aerobic microorganisms under controlled conditions."— Presentation transcript:

0 Composting and Compost Utilization
Andy Bary WSU Puyallup Oct 3, 2002

1 Composting Decomposition of organic materials by aerobic microorganisms under controlled conditions

2 Why compost Compost good soil conditioner Improved manure handling
Improved land application Lower risk of pollution Pathogen destruction Nutrient management Disease suppression Saleable product??? Tipping fees

3 Compost Draw backs Time and money Lack of equipment Land Odor Weather
Materials N loss Farm operation

4 Composting Process Flow Chart Compost Quality Assessment
Acquire Feedstocks Analyze Markets Amendments Determine Recipe Bulking Agents Prepare Material sort, grind, chip, mix, shred Active Composting Low Tech High Tech Curing Time Screening “overs” Compost Quality Assessment Product Refinement & Marketing Blending Bagging Adapted with permission from the On-Farm Composting Handbook. Additives Storage

5 Factors that affect composting
Oxygen C:N ratio Moisture Porosity, structure, particle size pH Temperature Time

6 Reasonable ranges Preferred ranges C:N ratio : :1 H2O content % % O >5% >5% Particle size 1/8-1/2in. varies pH Temperature F

7 Carbon:Nitrogen Ratio
Compost :1 Grass clippings 15:1 Biosolids 5:1 Food wastes 15:1 Dairy manure 20:1 Leaves and foliage 60:1 Straw 80:1 Bark :1 Paper :1 Wood or sawdust 500:1

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9 Composting methods In vessel Aerated static pile Passively aerated systems windrow bunker

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12 Composting methods In vessel Aerated static pile Passively aerated systems windrow bunker

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14 Composting methods In vessel Aerated static pile Passively aerated systems windrow bunker

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21 What can I compost? Animal manures Straw, hay Vegetable matter
Yard debris Wood shaving/chips Newspaper Fruit and vegetable wastes Fish processing wastes

22 Organic Production Manures
Raw manure OK if crop is not for human consumption Incorporated >120 days before harvest if edible is in direct contact with soil or soil particles Incorporated >90 days before harvest if edible is not direct contact with soil or soil particles

23 Organic Production Compost non animal materials
Plant residues, etc No specific composting regulations

24 Organic Production Compost animal materials
Initial C:N 25:1 – 40:1 Meet PFRP In vessel or covered oF, 3 days, All portion of pile meets this temperature. Turned windrow oF, minimum 15 days with 5 turns.

25 Soil fertility and nutrient management

26 Nutrient Management Meet crop nutrient needs Maintain soil quality
Conserve resources Protect water quality -- reduce leaching and runoff risk

27 Plant Nutrients Major Nutrients Micronutrients Nitrogen Phosphorus
Potassium Calcium Magnesium Sulfur Micronutrients Boron Iron Manganese Zinc Copper Chloride Molybdenum

28 How nutrients become available
Mineral Matter Organic Matter K N Not available P Mg Ca S - - K+ NH4+ Ca++ SO4-- soluble, available Mg++ Ca++ K+ - - - - - - - K+ - - - - - - - - clay OM

29 Nutrient Anion Availability
Anion Binding Solubility PO4-3 strong low BO3-3 medium medium SO4-2 v. weak high NO3- v. weak v. high

30 Nitrogen Cycle Organic N NH4+ NO3 - Plant residues, Manure Plants,
Microbes NO3 - Leaching Gases

31 Organic Materials Little or no processing Low nutrient content
Slow release of nutrients Plant, animal, or mineral sources

32 Heated >150oF for 1 hour and less than 12% moisture
Processed Manures Heated >150oF for 1 hour and less than 12% moisture

33 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.

34 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.

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

36 Organic materials: Fertilizers vs. Soil amendments
Fertilizer 1. High nutrient content and availability Main benefit is nutrients. 3. Relatively small amounts applied. Soil amendment 1. Low nutrient content and availability Main benefit is organic matter Large amounts applied.

37 Carbon:Nitrogen ratio
Low C:N supplies N to plants High C:N ties up N by biological immobilization

38 C:N ratio and N availability
<10:1 10:1 to 20:1 20:1 to 30:1 >30:1 N availability High Med - Low Very Low Negative

39 High N Content C: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.

40 High N Content Examples
Poultry manure Packaged organic fertilizers Fresh dairy or goat manure

41 Moderate N Content C: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.

42 Moderate N Content Examples
Compost Yard debris Cover crop residues Dairy solids

43 Low N content C:N > 30:1 N immobilization
Need to add N along with organic amendment Use as mulch or bulking agent for compost

44 Low N content Examples Straw Sawdust Paper waste

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46 Happy Composting

47 Cl Clopyralid in Compost Cl COOH N What’s the story?

48 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.

49 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.

50 Clopyralid Other sources of contamination
Manure from horses fed grass hay treated with clopyralid Straw from grain crops treated with clopyralid

51 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.

52 Peas, beans and marigolds grown in 3:1 v/v compost:perlite mix Peas and beans show symptoms, marigolds show no symptoms.

53 Leaf from tomato plant grown in unamended soil. Leaf from tomato plant grown in soil amended with 50% compost.


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