Composting methods

Cold vs. hot:

  • Cold composting - placing whatever organic materials in a compost bin, enclosure, or even just in a large heap, then leaving it there until it breaks down several months later. This can take 6-12 months before producing usable compost. It can be somewhat sped up by turning the heap every now and then to increase the amount of oxygen
  • Hot composting - involves getting the compost really hot, usually through the use of certain microorganisms. This can kill certain pathogens and produce usable compost much faster
    • Berkeley hot composting method[1] - a type of hot composting method which can produce compost in 2-3 weeks. Temperature must be maintained between 55-65°C (130-150°F). To do this, the overall carbon-nitrogen ratio must be kept at around 24-30:1 (for every one unit of nitrogen used by bacteria they also consume about 30 units of carbon.). The heap should be around 1.5m (almost 5ft) high. High carbon material should be broken down with a mulcher/shredder. Compost is turned from outside to inside to mix thoroughly. Basically, the steps are: (1) build compost heap; (2) after 4 days turn it; (3) then turn it again every other day for 14 days.

Open vs. direct:

  • Open air composting - a pile of greens and browns
  • Direct composting - digging a hole in the ground and burying your scraps. Can take a long time to decompose unless you chop up everything. Might be dug up by other animals, but also attracts and abundance of worms

More techniques:[2]

  • Tumbler composting - you put your compost in a compost tumbler and turn it every few days
  • Worm farm composting (vermicomposting) - make a worm bed/container to start a worm farm which you feed organic matter to. The worms break down the matter and also produce worm castings which is a useful compost material. Additionally, they can produce compost tea which can be sprayed to introduce beneficial microorganisms to plants
  • Effective microorganism (EMO) composting - techniques like bokashi composting technically don't decompose the matter but simply ferment them to make useful soil amendments. Essentially, you use microorganisms to ferment the organic matter. The EMOs can also be used in other composting methods however.
  • Combination composting - a combination of open-air, direct, vermicomposting, and EMO composting. You can use different techniques for different materials
  • Commercial composting - made in long rows using materials like sawdust, pine bark, sand plus ferrous sulphate, and maybe some sulphate of ammonia all mixed together and usually turned every 3/4 days for 6 weeks.
  • Mechanical composting - uses electricity to create the heat and rotate the contents in order to quickly (semi-)compost the waste. Useful for large institutions that produce a lot of waste (i.e. schools, businesses, hotels, hospitals, etc).

My suggestion edit

  1. Shred/mulch/blend the organic matter (browns and greens, but browns especially).
  2. Pay attention to the ingredients and calculate your overall C:N ratio and try to get it to around 25:1. Additionally, look out for any ingredients that might make the pH too acidic or alkaline. Also make sure there are good sources of specific minerals. Add special ingredients as needed.
  3. Make a heap of compost that's about a 1.5m cube. You can add bokashi or other EMOs to help ferment. You should at least add some healthy soil to introduce certain microbes. You can also make sure worms are in the mix to help out.
  4. Keep it in the sun, but water it to make sure it doesn't dry out. After 4 days, take the outsides of the heap and put it in another heap. Then take the insides and make a wall around the outside bits with the inside bits.
  5. Repeat step 4 until you have good quality compost (~2 weeks). After you plant your plants, you can add mycorrhizal fungi mix.

General tips edit

  • Sun and moisture are important, but avoid too much sun or too much rain as it can dry out or waterlog your compost.
    • You want your moisture content to be around 50-60%. If you can squeeze water out, the compost is too wet. If it crumbles apart when released, it's too dry. Alternatively, you can weigh some compost, dry it thoroughly (oven), and weigh it again.[3]
  • It's not clear that layering is actually necessary or useful and I couldn't find that it provides any benefits besides being able to sort how much of each type you have (i.e. 3 layers of brown and 1 layer of green is easier to keep track of than weighing all your materials).
  • If the temperature gets over ~65°C (149°F), aerate or turn the pile to cool it down. Temperatures that high kill most microorganisms and limit the rate of decomposition. Make sure the temperatures are above 55°C (131°F) however since this is where most microbes that are pathogenic to humans and plants die.[4]
  • The reason you want a larger compost heap is that it is better at keeping the heat in the middle. However, if you can find another way to keep the heat from escaping (without blocking aeration too much), you can get away with a smaller pile.
  • Certain organic material can be useful for creating more aeration spaces.
  • Some materials will take longer to decompose (important to note that there are many forms of carbon and complex chemicals like lignan will take much longer to break down than sugars. Ultimately, the C:N ratio is just a rule of thumb). If you have a screen, you can separate the good crumbly compost from pieces that haven't decomposed. Then you can collect those pieces and add them to the next heap.[5]

Organisms involved edit

Under optimal conditions, composting will go through three phases: the mesophilic (moderate temperature) phase, the thermophilic (high-temperature) phase, and a cooling down/maturation phase. Throughout the different phases, different microbes will be predominant. Initially, mesophilic microorganisms will quickly break down the soluble, readily degradable compounds. This activity causes heat and raises the temperature of the compost rapidly. As temperatures get above 40°C (104°F), mesophilic microbes will become less dominant and thermophilic ones will take their place. When the temperature reaches 55°C (131°F), most microbes that are pathogens for humans or plants will die. However, if the temperature is allowed to get over 65°C (149°F), most organisms will struggle to survive and the rate of decomposition will decrease. During the thermophilic phase, the breakdown of proteins, fats, and complex carboydrates like cellulose and hemicellulose is accelerated. As these high-energy compounds become exhausted, the temperature gradually decreases and mesophilic organisms take over again.

Bacteria edit

Bacteria make up 80-90% of the microorganisms found in compost.

Carbon-nitrogen ratios edit

Materials with low C:N ratios rot very quickly (i.e. fish), while stuff like tree branches would need to be broken up as they take much longer. Breaking up the material increases the surface area.

  • cheese whey (2411:1[6])
  • shredded newspaper (175:1[7][5], 400-800:1[8])
  • newspaper or corrugated cardboard (560:1[9])
  • wood chips (400:1[7][5])
  • shredded cardboard (350:1[7][5])
  • sawdust (325:1[7][5])
  • wood chips or sawdust (100-500:1[9][8])
  • mixed paper (150-200:1[9])
  • paper (150-200:1[8])
  • bagasse (137:1[6])
  • bark (100-130:1[9][8])
  • corn cobs (50-120:1[8])
  • rye straw (82:1[10])
  • wheat straw (80:1[10])
  • pine needles (80:1[7][5][8])
  • corn stalks (75:1,[7][5] 80:1[8])
  • straw - oats and wheat (70-80:1[8])
  • straw (40-100:1,[9] 75:1[7][5])
  • oat straw (70:1[10])
  • leaves (60:1,[7][5] 40-80:1[8])
  • corn stover (57:1[10])
  • autumn leaves (30-80:1[9])
  • manure with litter - horse (30-60:1[8])
  • rye cover crop (anthesis) (37:1[10])
  • fruit waste (35:1[7][5][8])
  • peanut shells (35:1[7][5])
  • garden waste (30:1[7][5])
  • weeds (30:1[7][5])
  • pea straw (29:1[10])
  • fresh banana peel (28:1[6])
  • dry banana peel (26:1[6])
  • rye cover crop (vegetative) (26:1[10])
  • wood ashes (25:1[7][5])
  • green wood (25:1[7])
  • hay (25:1[7][5])
  • mature alfalfa hay (25:1[10])
  • cow dung (25:1[6])
  • vegetable scraps (25:1,[7][5] 15-20:1[9])
  • clover (23:1[7][5])
  • manure - cow and horse (20-25:1[8])
  • apple pomace (21:1[8])
  • coffee grounds (20:1[7][5][9][8])
  • food waste (20:1[7][5])
  • rotted barnyard manure (20:1[10])
  • grass clippings ( 20:1,[7][5] 15-25:1,[9] 12-25:1[8])
  • molasses (19:1[6])
  • seaweed (19:1[7][5])
  • horse manure (18:1[7])
  • legume hay (17:1[10])
  • beef manure (17:1[10])
  • dry potato peel (17:1[6])
  • fresh potato peel (16.5:1[6])
  • vegetable waste (12-20:1[8])
  • cow manure (16:1,[7] 20:1[8])
  • manure with litter - poultry (13-18:1[8])
  • manures (15:1,[5] 5-25:1[9])
  • young alfalfa hay (13:1[10])
  • alfalfa hay (13:1[8])
  • alfalfa (12:1[7][5])
  • press mud (12:1[6])
  • chicken manure (12:1[7])
  • hairy vetch cover crop (11:1[10])
  • pigeon manure (10:1[7])
  • manure - poultry (fresh) (10:1[8])
  • soil microbes (average) (8:1[10])
  • fish (7:1[7])
  • blood meal (4:1[8])
  • urine (1:1[7])

Special ingredients edit

Diseases and pathogens edit

Almost anything organic can be composted. In cold composting, you should avoid diseased leaves, manure, meat, and other possible disease vectors. With hot composting, you may be able to compost it if you can keep it in the center to make sure it breaks down properly.

pH edit

A pH between 5.5 and 8.5 is optimal for compost microorganisms.

Oxygen edit

Nutrients edit

Adequate phosphorus, potassium, and trace minerals (calcium, iron, boron, copper, etc.) are essential to microbial metabolism.

External edit

  1. ^ "How to Compost in 14 days: How to Make Fast Compost". Compost Info Guide.
  2. ^ "8 Methods of Composting". Direct Compost Solutions.
  3. ^ "Measuring moisture in your compost pile". Compost Info Guide.
  4. ^ "Compost Microorganisms". Cornell Composting.
  5. ^ a b c d e f g h i j k l m n o p q r s t u v w "Wanted: More Compost". Planet Natural Research Center.
  6. ^ a b c d e f g h i "A Method to Utilize Waste Nutrient Sources in Aqueous Extracts for Enhancement of Biomass and Lipid Content in Potential Green Algal Species for Biodiesel Production". Oa.mg.
  7. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab "How to Make Compost in 18 Days Using the Berkeley Hot Composting Method". Deep Green Permaculture.
  8. ^ a b c d e f g h i j k l m n o p q r s t u "Garden Compost". NebGuide Nebraska Extension.
  9. ^ a b c d e f g h i j "Compost Chemistry". Cornell Composting.
  10. ^ a b c d e f g h i j k l m n "Carbon to Nitrogen Ratios in Cropping Systems" (PDF). USDA Natural Resources Conservation Service.
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