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COMPOSTING Duane Friend Educator in Environmental Stewardship and Energy University of Illinois Extension University of Illinois Extension Overview • History of composting • Basic processes • Benefits of compost • Uses of finished compost • Field studies in Illinois using compost World Prehistoric farmers discovered that by piling mixtures of animal manure, plant debris, and • soil the process of decomposition that occurs in nature is sped up. The resulting product – called compost or humus – is still the primary source of soil nutrients in many parts of the world. North America Native Americans Early European settlers – compost made of 10 parts muck to 1 part fish, periodically turning the heap until fish disintegrated George Washington, Thomas Jefferson , George Washington Carver – promoted use of compost Composting Today University of Illinois Extension THE COMPOSTING PROCESS MICROORGANISMS OXYGEN WATER ORGANIC MATERIALS HUMUS CARBON DIOXIDE University of Illinois Extension HEAT WATER THE COMPOSTING PROCESS AND CRITTERS INVOLVED University of Illinois Extension Compost Biology • Compost Ecosystems/Food Web • Organisms University of Illinois Extension Where do the decomposers come from? Penn State • Soil • Leaves • Food scraps • Manure, and • Finished compost “Microorganisms found on the surface of leaves, grass, and other incoming organic matter are fully capable of starting and sustaining the compost process.” Winn. Co. Master Composter Manual, 1992 (Slide courtesy John Church) What Soil/Compost Organisms Do • • • • Nutrient Cycling Nutrient Retention Improved structure Improved water infiltration/holding capacity • Disease suppression • Degradation of pollutants University of Illinois Extension Soil/Compost Food Web From: The Soil Biology Primer, published by the Soil and Water Conservation Society in cooperation with the USDA Natural Resources Conservation Service Seasonal Activity From: The Soil Biology Primer, published by the Soil and Water Conservation Society in cooperation with the USDA Natural Resources Conservation Service University of Illinois Extension One teaspoon of good garden soil to which compost has been added contains: • 100 million bacteria • 800 feet of fungal threads University of Illinois Extension Bacteria AEROBIC BACTERIA • Bacteria that function only in the presence of oxygen University of Illinois Extension AEROBIC BACTERIA • Utilize carbon as a source of energy • Utilize nitrogen to build protein University of Illinois Extension AEROBIC BACTERIA • Psychrophilic- Active at 55 to 70 degrees • Mesophilic- Active at 70 to 100 degrees • Thermophilic- Active at 113 to 160 degrees University of Illinois Extension ANERORBIC BACTERIA • Bacteria that function in the absence of oxygen • Produce organic acids, amines, and hydrogen sulfides, cadaverine, and putrescine University of Illinois Extension Fungi • Parasitic or pathogens • Found in later stages of the process University of Illinois Extension MACROORGANISMS University of Illinois Extension KEY FACTORS AFFECTING THE COMPOSTING PROCESS University of Illinois Extension FOOD FACTOR • Organic materials provides carbon and nitrogen for microorganisms • Nitrogen is usually the limiting factor University of Illinois Extension CARBON/NITROGEN RATIO • The amount of carbon compared to the amount of nitrogen in a substance • Carbon for energy source and nitrogen to build cells • Carbon amounts are always higher than nitrogen University of Illinois Extension University of Illinois Extension University of Illinois Extension University of Illinois Extension A C/N RATIO OF 25:1 IS IDEAL FOR RAPID COMPOSTING • Blending of materials is necessary • Try to have 1/4 to 1/2 of materials in high nitrogen category University of Illinois Extension MATERIALS WITH HIGH NITROGEN VALUES MATERIAL Food wastes Grass clippings Cow Manure Horse Manure Coffee grounds C/N RATIO 15:1 20:1 20:1 25:1 20:1 MATERIALS WITH HIGH NITROGEN VALUES • • • • Legume Hay Dried Blood Chicken Manure Sheep Manure University of Illinois Extension 20:1 3:1 10:1 16:1 MATERIALS WITH HIGH CARBON VALUES MATERIAL Leaves Straw Sawdust Paper C/N RATIO 80:1 80:1 500:1 200:1 MATERIALS WITH HIGH CARBON VALUES • • • • • Corn stalks Hardwood Bark Hardwood Shavings Softwood Bark Softwood Shavings 70:1 225:1 560:1 500:1 640:1 University of Illinois Extension High carbon materials such as Leaves (30-80:1) Straw (40-100:1) Paper (150-200:1) Sawdust (100-500:1) Animal bedding mixed with manure (30-80:1) Penn State Slide courtesy John Church High nitrogen materials such as Vegetable scraps (12-20:1) Coffee grounds (20:1) Grass clippings (12-25:1) Manure – Cow (20:1) – Horse (25:1) – Poultry (10:1), with litter (13-18:1) – Hog (5-7:1) Penn State Slide courtesy John Church Master Composter Resource Manual, 1998 Cornell University Slide courtesy John Church AIR FACTOR • Microorganisms need oxygen to function • Affected by wind, moisture, and porosity University of Illinois Extension Oxygen Needed for Aerobic Composting • Optimal oxygen concentrations are in the 10-16% range for fast composting, although in some cases odors may not be an issue until oxygen levels drop below 5% University of Illinois Extension WAYS TO KEEP OXYGEN IN GOOD SUPPLY • Monitor oxygen • Periodic turning Photo from Midwest Bio Systems • Keep pile from being too wet • Add coarse materials University of Illinois Extension Maintain moisture similar to a damp sponge Slide courtesy John Church Moisture • Optimal range 46-65% • Low moisture limits microbial activity • High moisture limits oxygen availability University of Illinois Extension TEMPERATURE FACTOR • Temperatures of 90 to 140 degrees indicate rapid decomposition • Temperatures above 131 degrees needed to kill pathogens • Above 160 reduces microbial activity • At 179 degrees, all beneficial microbes are killed • 204 degrees- spontaneous combustion University of Illinois Extension Temperature and Weed Seed Mortality • Dahlquist et al. (2007) estimated that three of the six weed species they examined under controlled laboratory conditions were unaffected by temperatures of 108 °F, but 90% of the seeds of all six species were killed after less than three hours at 140 °F . Furthermore, all six species suffered 100% mortality after less than an hour at 158 °F From : Composting to Reduce Weed Seeds and Plant Pathogens, U of I Extension University of Illinois Extension TRACKING TEMPERATURE • Compost thermometers University of Illinois Extension PARTICLE SIZE FACTOR • Affects rate of decomposition • The smaller the size, the more surface area provided for microbes to work on • Very small particles limits oxygen • Ideal range 1/8 to ½ inch University of Illinois Extension VOLUME FACTOR • Needs to be big enough to retain heat • Can be as large as equipment will allow, as long as temperature and oxygen levels are managed University of Illinois Extension pH • Initial pH will vary according to feedstock, but finished compost will generally be in the 6.0 to 7.5 range. University of Illinois Extension WHEN TO START • Can be started any time of year, but may be limited by availability of carbon rich or nitrogen rich materials University of Illinois Extension Recommended Conditions for Composting • • • • • C:N ratio- 20:1 to 40:1 Moisture content- 40-65% Oxygen concentration- > 5% Particle size- 1/8 to ½ inch Temperature- 110-150o F. University of Illinois Extension Active Composting Time • Passive composting- 1 to 2 years • Infrequent turning- 6 mo. to 1 yr. – Curing time 1 to 4 months • Frequent turning- 2 mo. To 6 mo. – Curing time 1 to 2 months University of Illinois Extension PROBLEMS University of Illinois Extension ODOR • Not enough oxygen – Overwatering – Compaction – Too much nitrogen University of Illinois Extension PILE NOT HEATING UP • Not big enough • Not enough moisture or air • Not enough nitrogen • Compost may be finished University of Illinois Extension COMPOST IS DAMP AND WARM ONLY IN CENTER • Pile is too small University of Illinois Extension LARGE UNDECOMPOSED ITEMS STILL VISIBLE • Not enough surface area University of Illinois Extension RODENTS AND PETS • Presence of meat • scraps University of Illinois Extension BENEFITS AND USES OF COMPOST University of Illinois Extension FINISHED COMPOST • Has dark color, earthy smell, and is crumbly • Let finished compost sit at least 3 weeks to make sure decomposition process is complete University of Illinois Extension Curing Compost • Compost just finishing the active cycle may contain higher amounts of ammonium- may affect plants especially sensitive to this type of N. • Curing allows ammonium to convert to more plant tolerable N. University of Illinois Extension Simple tests for finished compost Bag test: sealing compost in a plastic bag for several days should produce no foul odor Germination test: will seeds germinate in the compost? (good test to use if compost will be part of a potting mix) Slide courtesy John Church Penn State Maturity Index • The Solvita test measures CO2 and Ammonia University of Illinois Extension Solvita Tests • Solvita® detection is based on a gelcolorimetry technique, analogous to Beer-Lambert’s law governing optical-chemical reactions to changing concentrations of dissolved molecules, such a H-CO3 and NH3OH University of Illinois Extension Compost Application Studies in Illinois University of Illinois Extension Incorporating high-quality compost has been shown to improve soil quality. Multi-year study on irrigated plots east of Havana, Illinois in Mason County (sandy soils). Annually applied rates of 10 and 20 dry tons per acre of compost to plots over a four-year period -- Soil tests were conducted each year to see whether there were any changes in organic matter content, cation exchange capacity, or other physical and chemical characteristics. Duane Friend, U. of I. Extension Educator, NRM Springfield, March, 2007 Nine Sub plots • Rates of 0, 10, and 20 wet tons acre of compost • Measure soil changes • Measure soil moisture during growing season • Measure yield within plots University of Illinois Extension 20 Dry Tons/Ac 60 Dry Tons/Ac University of Illinois Extension University of Illinois Extension University of Illinois Extension Average Organic Matter Contents for Plots 2003- taken 11 months after 1st application 2004- taken 11 months after 2nd application 0.45 0.4 0.35 0.3 Organic 0.25 matter in 0.2 percent 0.15 0.1 0.05 0 0 tons/ac 10 tons/ac 20 tons/ac 2003 2004 University of Illinois Extension Average Cation Exchange Capacity for Plots 7 6 5 CEC value 4 0 tons/Ac 10 tons/Ac 20 tons/Ac 3 2 1 0 2003 2004 Statistically significant at 20 tons/ac University of Illinois Extension Average Relative Soil Water Content 70 60 50 Relative water 40 content in 30 percent 20 0 tons/ac 10 tons/ac 20 tons/ac 10 0 2003 2004 University of Illinois Extension 2004 Yield Results- Popcorn 6350 6340 6330 6320 6310 Pounds/Acre 6300 6290 6280 6270 6260 0 tons 10 tons 20 tons Conclusions of Study • Was slowly improving soil quality • May take years of application to affect yields at low rates of application • Phosphorus levels should be monitored if using a high P compost feedstock Compost/Sediment Field Study • Applied ratio’s of compost and sediment for a total application rate of 60 dry tons/ac. • • • • 25% compost / 75% sediment 50/50 75% compost / 25% sediment 0 (control) • 3 replications of each University of Illinois Extension Lake Decatur University of Illinois Extension University of Illinois Extension Compost Sediment University of Illinois Extension Compost and Sediment Control Compost and Sediment University of Illinois Extension Sub plot average of popcorn yield in pounds/acre 5000 4000 3000 2000 1000 0 0 25/75 50/50 75/25 Test Weight of popcorn 66.2 66 65.8 65.6 65.4 65.2 65 64.8 64.6 0 25/75 50/50 75/25 Conclusions of compost/sediment study • Yields increased, but not statistically significant • Test weights of popcorn increased where compost/sediment applied • Ratios of compost/sediment did not appear to make a difference University of Illinois Extension USES OF COMPOST • Mulch • Soil Amendment • Potting mixes • Compost tea University of Illinois Extension FINISHED COMPOST: SCREENING For high quality use, screening needed to remove clay balls and remaining uncompostables Slide courtesy John Church Compost as Mulch • Do not use more than 2-3 inches • Do not place in direct contact with trunk of trees • Excellent for erosion control University of Illinois Extension University of Illinois Extension