Composts

1. Composts • What is compost and why use it? • What organisms are involved in the composting process? • What chemical changes occur during composting? • What are the optimal conditions for composting • Temperature • Moisture • Oxygen • Does composting kill harmful pathogens (plant and human), nematodes and weed seeds? • Safety regulations • Compost production systems • Small scale • Commercial

2. What is compost – why use it? Composting is the decomposition of plant remains and other once-living materials to make an earthy, dark, crumbly substance that is excellent for adding to houseplants or enriching garden soil. • compost improves soil structure, texture, aeration - increases the soil's water-holding capacity. • Compost loosens clay soils and helps sandy soils retain water. • improves soil fertility and stimulates healthy root development • Organic matter provides food for microorganisms - nitrogen, potassium, and phosphorus mineralized

3. Top 10 Reasons to Compost 10.Be environmentally responsible. 9. Reduce need for chemical fertilizers, mulch. 8. Create a healthy landscape. 7. Improve the quality of your soil. 6. Reduce amount of yard waste going to landfill. 5. Protect the Chesapeake Bay and watershed. 4. Decrease water use in your landscape. 3. Protect privacy. Use shredded personal papers! 2. It's easy. Good exercise. 1. Free bin for Howard County residents!

4. The Science of Composting • Composting is the natural process in which living organisms decompose organic matter into inorganic matter in the soil. • The organisms feed on the organic material and through respiration generate the energy that they use for movement, growth, reproduction or stored energy. • The organism excrete inorganic material that enriches the soil. • When the organisms die, their bodies add to the organic matter in the compost pile.

5. Fresh Organic Materials Oxygen + Microbes, Moisture, and Time Compost Energy Carbon Dioxide + + Slide credit: Tom Richard, Penn State University

6. Organisms use carbon as a source of energy and nitrogen to grow and reproduce. • Too little N: • there will be few microorganisms, and decomposition will be slow. • Too much N: • some will turn to ammonia that will volatilize, creating an odor.

7. Factors affecting the compost process C:N ratio Size and texture Aeration NB. Moisture level also critical

8. Moisture level is also critical • Optimum moisture content 40-60% • Feels moist to touch, but when squeezed only produces few drops

9. Ideal conditions for composting

10. The Science of Composting:Chemistry Important factors in compost chemistry • Oxygen • Needed to oxidize carbon for energy • Without oxygen will produce rotten egg smell • pH Level • Acids form as organisms digest organic material and lowers pH • Lower pH encourages fungi and the break down of “tough” matter • If pH too low (<4.5) limits microorganisms’ activity

11. The Science of Composting:Physics Important factors for compost physics: • Temperature • 3 Phases • Want to maintain temperature between 55-600C • Temperature impacted • Heat generated by organism • Heat lost to environment through conduction, convection and radiation  shape and size of pile • Moisture content (specific heat and heat capacity of water)

12. The Science of Composting:Physics Important factors for compost physics: • Particle size • Microorganism activity occurs on surface of organic material • The more surface area for organisms to attack, the quicker the decomposition  want smaller particles • Flip-side: The smaller the particles, the more dense and compact the material resulting in poor oxygen circulation

13. The main players • Bacteria:major decomposers, breakdown simpler forms of organic material • Actinomycetes:degrade complex organics such as cellulose, lignin, chitin, and proteins –earthy” smell, long “spider webs” filaments • Fungi:Break down tough debris, too dry, too acidic or too low in nitrogen for bacteria to eat

14. What do microbes in compost do? • Consume organic matter to grow • Stabilize organic matter • Aerobic oxidation produces CO2 • Anaerobic produces reduced compounds organic acids, alcohols • Mineralize nutrients • Organic to inorganic forms (protein to NH4) • Transform nutrients • Nitrification – pH and temperature sensitive • NOTE: invertebrates not important in high temperature composting, only in cold

15. Starting your Compost Pile - Ideal size is 3 ft. x 3 ft. x 3 ft. (27 cubic ft.) Easier to turn, aerobic action • No larger than 5 x 5 x 5 • Can become anaerobic

16. Compost production systems • Small scale Compost piles need to be at least one cubic to hold the heat from decomposition

17. Passive composting

18. Commercial composting • Large scale • Passive aeration with turning or actively aerated systems

19. Vermicomposting Vermicomposting is the process of using worms and micro-organisms to turn kitchen waste into a black, earthy-smelling, nutrient-rich humus. The worms used in vermicomposting are called redworms (Eisenia foetida), also know as red wigglers, manure worms, red hybrid or tiger worms. http://lancaster.unl.edu/pest/resources/vermicompost107.shtml

20. Feedstock conditioning - grinding

21. Moisture management - most important factor to stabilize biological and chemical properties

22. Processing – turned windrows

23. Compost blankets to moderate moisture www.vanierselcompost.com/. ../productie.htm

24. Composting - windrow Turning helps aeration and to move material from edge into hot center region CO2 Hot O2 Cool Graphic credit: Tom Richard, Penn State University

25. Composting – Static forced air CO2 • Air forces heat outwards • Some systems can switch direction to keep base core at high enough temperature • Also helps control odor Hot O2 Cool Graphic credit: Tom Richard, Penn State University

26. Processing - forced aeration

27. Contain, treat leachate

28. Compost blankets – beware moving from fresh to curing www.vanierselcompost.com/. ../productie.htm

29. Cure compost with 40-50% moisture to promote competitive microorganisms and avoid salmonella regrowth