composting 101

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Composting 101. The what, when, where, why and how of composting. Download a copy of the presentation Get a copy of Microsoft Power Point Viewer (free). Home Page: Minnesota waste facts. Statewide recycling rate - 47.2% - PowerPoint PPT Presentation


  • Composting 101The what, when, where, why and how of compostingHome Page: a copy of the presentation Get a copy of Microsoft Power Point Viewer (free)

  • Minnesota waste factsStatewide recycling rate - 47.2%

    Minnesotans threw away 3 million tons of garbage in 1999Organic materials comprise of 25.4% of statewide residential waste (most of which is compostable)Paper products make up 30.8% of statewide residential waste

  • What is compost?End product of the decomposition of organic materials by decomposersValuable soil amendmentDark, crumbly and earthy smelling materialA resource that can be utilized in your own back yard

  • Why should I compost?There are many benefits to compostingValuable soil amendmentEffective mulchReduction in waste

  • Soil amendmentImproves soil structureIncreases aerationHolds moistureEspecially important in sandy soilPromotes plant growthContains essential micronutrientsStores nutrientsPorous structure stores nutrients

  • Soil amendmentFlower and vegetable gardensDig or till 8 to 10 inch deepMix 3 to 4 inches of compost through entire depthSeeding new lawnsTill soil 6 inches deepMix in 4 inches of compost

  • MulchSuppress weedsMaintain moisture levelsControl temperaturePrevent soil erosion

  • MulchGardensSift compost to remove large, woody materialApply 1/2 to 1 inch layerKeep a few inches away from base of plantsTrees and shrubsRemove sod from base of plantUse coarse compostErosion controlUse 2 to 4 inches coarse compost

  • Reduce wasteReduce the amount of waste sent to landfills and incineratorsOften illegal to dispose of yardwaste with other municipal solid waste

  • How does compost happen?Organic material is processed (for free) by numerous decomposersBacteriaFungiInvertebratesWormsNematodesSpringtailsDecomposers need food, nutrients, air and water (you will need to supply these)Decomposers also need heat but they supply their own

  • Decomposers microorganisms and soil animalsThe food web in your compost pile supports a wide variety of lifeforms from microscopic bacteria to larger beetles and worms.

  • Decomposers - bacteriaMost numerous organisms in compost pileDont need to be added to compost pile, they are present virtually everywhere!Generate heat associated with compostingPerform the primary breakdown of organic materialsThere are different bacteria present at different temperatures

  • Bacteria groupsPsychrophilic bacteriaIdeal temperature is around 55F but they are able to survive right down to 0FMesophilic bacteriaThrive at temperatures between 70-90 F and can survive from 40-110 F Thermophilic bacteriaWork fastest in temperatures from 104-170 FMost efficient decomposers

  • Decomposers - bacteriaInteresting fact - less than a teaspoon of the common bacteria Escherichia coli, would become a pound in 3 hours and a mass the size of the Earth in a day and a half if sufficient food and proper conditions were available!

  • Decomposers - fungiPerform primary decompositionIdentified by their root-like fibers or presence of mushrooms

    Not as efficient as bacteriaLess temperature tolerant than bacteria

  • Decomposers - nematodesMost abundant invertebrate in the soilUsually less then 1 millimeter in lengthPrey on bacteria, protozoa, fungal spore and each other

  • Decomposers - mitesCalled fermentation mites or mold mitesTransparent-bodied creaturesFeed on yeastMasses often develop over fermenting surfaces

  • Decomposers - collembulaAlso know as springtailsFeed mainly on fungi but also eat nematodes and organic detritusMajor population controlling factor of fungi

  • Decomposers - wolf spidersBuild no websRun freely hunting preyPrey on all sizes of arthropods

  • Decomposers - centipedeFrequently found in soil and compost microcommunitiesPrey on almost any type of soil invertebrate near their size or slightly larger

  • Decomposers - sow bugFeed on rotting woody material and leaf tissueAlso know as pill bugs or roly polys

  • Decomposers - ground beetleMany different types can be found in and around compost pilesMost feed on other organisms, but some feed on seeds and vegetable matter

  • Decomposers - redwormsCoat processed organic material with mucus films thatBinds small particles togetherLeads to loose and well drained soilProtects soil against nutrient leaching

  • Other compost residents - pestsCommon pests may include house and fruit flies, rodents, raccoons, and domestic animals such as cats and dogsProper bin maintenance and selective material usage will reduce your risk of pest problems

  • Pest controlAvoid composting meat and dairy products and other fatty foodsAvoid adding pet food or feces to your compost pileCover other food waste with a layer of grass, straw, leaves, paper or finished compost

  • What are the key ingredients?Materials (C:N ratio)Moisture and aerationParticle size/surface areaTemperature

  • C:N RatioAll living organisms need relatively large amounts of carbon and smaller amounts of nitrogenMicroorganisms in compost use carbon for energy and nitrogen for protein synthesis

    Generally...Green materials = nitrogenex. green grass clippingsBrown materials = carbonex. autumn leaves, straw

  • The ideal ratio of carbon:nitrogen of 30:1 will ensure maximum bacteria decompositionMix based on weight not volumeThese are only guidelines, actual values may very (Ex. leaves from different trees will vary in their carbon content)

    Average Carbon:Nitrogen Ratios Food Scraps 15:1 GREENSGrass Clippings 19:1Rotted Manure 25:1 30:1 Ideal for CompostingCorn Stalks 60:1Leaves 40-80:1Straw 80:1 BROWNSPaper 170:1Sawdust, woodchips 500:1

  • Moisture and aerationAll compost organisms need air and water to survive

    Strive for moisture content around 50%Without 40% the bacteria will slow downAt 80% and above there is not enough airspace and aerobic decomposition occurs which is slower and leads to odor problems

    Avoid compacting materials - this limits aeration in your pile

  • Moisture and aerationOptimal moisture levels occur when compost is as moist as a wrung out spongeWhen watering a dry pile be sure to mix Water will just shed off a dry pileMixing once or twice a month will increase rate of decomposition by increasing air spacesTakes 36 Xs longer if not turned

  • Particle sizeParticle size is an important factor in compostingReducing particle size increases the surface area available for decomposersHowever, if the pieces are too small they may compact together and limit aerationA mixture of small and larger particles is ideal

  • TemperatureHigh temperature compost pileFaster decompositionHelps insure weeds and pathogens are killed

  • What can be composted?Grass and yard trimmings/clippingsLeavesCoffee grounds/filtersTea leaves/bagsFruits and vegetable trimmingsWood chipsSawdustEgg shellsLivestock manure

  • What should not be composted?Diseased or insect infested plantsCat and dog manureEvergreen needlesPoison ivy and other poisonous plantsWeeds that contain seedsMeat and animal productsFatty foodsDairy products

  • Compost bin sizeFor fast efficient composting your bin needs to beLarge enough to hold heat and moistureSmall enough to admit air through the centerRule of thumbA compost pile need to be at least 3ft. by 3ft. by 3ft.Upper limits are about 5ft. by 5ft. by any length

  • Building your compost pileBuild in layers8 to 10 inches of brown materialSeveral inches of green materialOne inch of soilEstablish proper moisture contentAvoid compacting materials

  • Compost bin typesThere is a great deal of variety in composting structuresCompost bins vary in their cost, required labor, volume, and time required for finished compost

  • Open pilesSlowest rate of decompositionLeast expensive methodMinimal pest control and containment

  • Holding unitsHelps keep decomposing materials organizedReduces pest problemsRequires no turningRelatively slow rate of decomposition (6 months to 2 years)

  • Turning units

    Three-chambered binBarrel or drum composterAllow for easier mixing of materialsResult in a hotter pile and reduced composting time (as soon as 2-3 weeks)Usually more expensive and more labor intensive

  • LocationAvoid areas with drying wind

    Partial sun will help heat the pile

    Should be easily accessible yet not interfere with yard activities

    Should not be offensive to neighbors

  • Finished CompostAvoid using unfinished compost, organic acids may harm plant roots

    If compost is still hot, smells like ammonia, oryou can still identify much of the original organic material it is not ready to use yet

  • Finished CompostComposting is complete when the pile stays at or near the ambient temperature

    Finished compost is dark, crumbly, and has an earthy smell

    The volume of finished compost willhave been reduced by 30 to 50 percent

  • Problem solving what if?The pile smells like rotten eggs? Not enough air/too much water Add coarse material like dry leaves Pile should be wet like a wrung out spongeThe pile smells like ammonia?Too much nitrogen, not enough carbonAdd dry leaves, sawdust or straw

  • Problem solving what if?My compost pile is not heating up?Examine bin size, moisture content, air flow, and material ratios (C:N)

    My compost pile is attracting pests?Eliminate meat dairy products and fatty foods from binBury food waste under a few inc