Taking Compost to the Next Level Duane Friend University of Illinois Extension

Taking Compost to the Next Level Duane Friend University of Illinois Extension

What do YOU look for in a good finished compost?

FINISHED COMPOST Has dark color, earthy smell, and is crumbly No odors Ready to use as a plant growth medium

Ranges for Quality Finished Compost ph 6.8-7.3 Soluble Salts 0.35 0.64 ds/m Nitrogen 1-2% Phosphorus 0.6-0.9 % Potassium 0.2-0.5 % Moisture 45-50% Organic Matter 35-45% Particle size Passes 3/8 inch screen Bulk Density 900-1000 lbs/sq. yard Source: Testing Compost. ANR -15-03. Ohio State University Fact Sheet

Other Considerations

Temperatures needed to kill certain pathogens Source Tchoubanoglous et al. (1993). Organism Inactivation requirements Salmonella typhosa-death within 30 min at 130 degrees F and within 20 min at 140 degrees F Salmonella sp.-death within 1 h at 130 degrees F and within 15-20 min at 140 degrees F Eschericiacoli-Most die within 1 h at 130 degrees F and within 15-20 min at 140 degrees F University of Illinois Extension

Oxygen content Since most efficient composting is aerobic, need O2. Atmospheric O2 concentration: 21%. O2 levels in compost air shouldn t go below ~5% for aerobic composting; 10% optimal. University of Illinois Extension As pile heats up, more O2 will be consumed Source: Compost biology Power Point, Dr. Leslie Cooperband University of Illinois

Moisture content Optimal range is 45-60% by weight (like a damp sponge). Low moisture impedes composting process because microbes need water. Moisture content > 60% means pore spaces filled with water rather than air, which leads to insufficient O2, and anaerobic conditions. University of Illinois Extension Source: Compost biology Power Point, Dr. Leslie Cooperband University of Illinois

Temperature Higher temperatures result in faster breakdown of organic materials. Excessively high temperatures (> 70 degrees C or 170 degrees F) can inhibit biodegradation. Moisture moderates wide swings in temperature. University of Illinois Extension Source: Compost biology Power Point, Dr. Leslie Cooperband, University of Illinois

Carbon/Nitrogen Ratio Finished compost should have a Carbon/Nitrogen ratio of around 25:1 or lower. Ratios of 30:1 or higher indicate immature compost, in need of further decomposition.

Suggested Compost Classes Measurement Class A Class B ph 6 to 7.0 6 to 7.5 C/N ratio < 25 < 30 Particle size (inch) < 1/2 < 1 Moisture content (percent) Electrical conductivity (mmho/cm) < 50 - < 2.5 < 5.0 Compost Analysis: University of Missouri Extension http://soilplantlab.missouri.edu/soil/compost.aspx

ph Measure of acidity Ranges from 0-14. Lower number = more acidity Most plants like a ph of 6.3 to 7.0 Getting soil too far out of range can limit nutrient uptake or allow too much uptake, killing the plant Test Methods and Parameters. U.S. Composting Council

Vermicompostand ph Vermicompostusually has a ph of 7.0 or higher, so acid loving plants may not do well in this medium.

Nutrient Availability and ph

SOLUBLE SALTS (CONDUCTIVITY) Level of salts determined by its ability to conduct electricity. Plant nutrients supplied as salts Excess salts can poison plants. Most composts have a conductivity of 1 to 10 ds/m, compared to soil ranges of 0 to 1.5 ds/m.

V LOW <1 May be used as direct substitute for soils M LOW 1-2 Topsoil substitute, container media MEDIUM 2-5 Dilute 2-to 5-fold for most applications M HIGH 5-10 Dilute 3-to 10-fold for most applications V HIGH >10 Use only at low application rates Source: Woods End Laboratory.

Nitrogen-Phosphorus- Potassium Compost may act as a slow release fertilizer, but applications typically would need to be high.

Nitrogen For mature compost, it is desirable that most of the nitrogen be organic, and that the ammonia fraction be small. In mature compost it is expected to find appreciable amounts of nitrate (NO3). Source: Woods End Laboratory

Phosphorus 5 dry tons/acre of compost with 2% P 450 lbp2o5 equivalent 5 dry tons/acre of compost with 2% K 250 lbk2o equivalent Studies show that compost P can substitute nearly 1:1 for synthetic fertilizer

Manure Based Compost Excessive P and K loading an issue if the compost is manure-based

ORGANIC MATTER Organic matter improves soil structure, plant available water, and nutrient holding ability of soil Also adds (in good quality compost) healthy microbial communities to soil

MOISTURE Proper moisture in finished compost aids in application, and provides water for microbial communities in compost.

PARTICLE SIZE Particle size can affect how well compost can be used in specific applications.

COMPOST MATURITY Unfinished compost may have high amounts of ammonia, organic acids, or other substances.

Curing Compost Provides safety net in case composting isn t actually complete. Immature compost may have high C:N ratio (causing N deficiency), also reduces Oxygen content in soils.

Curing Compost Compost just finishing the active cycle may contain higher amounts of ammoniummay affect plants especially sensitive to this type of N. Curing allows ammonium to convert to more plant tolerable N.

Testing Labs A listing of testing labs can be found on the U.S. Composting Council s website at: http://compostingcouncil.org/labs/

DIY Maturity Testing Poor germination can be an indicator of maturity. Sometimes compost just won t pass the smell test!

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

GERMINATION TEST COMPOST SAMPLE 12 PLANTING CONTAINERS SAME SIZE 60 RADISH SEEDS TAPE LABELS AND MARKER POTTING SOIL

GERMINATION TEST LABEL/NUMBER 6 CONTAINERS AS THE CONTROL SAMPLES. INCLUDE DATE. LABEL/NUMBER OTHER 6 AS THE COMPOST SAMPLES. INCLUDE DATE. PLACE CONTAINERS IN A RANDOM PATTERN. PLANT SIX SEEDS IN EACH CONTAINER AND WATER.

GERMINATION TEST KEEP CONTAINERS MOIST AFTER A WEEK, COUNT AND RECORD THE NUMBER OF SEEDS GERMINATED CALCUATE GERMINATION RATE BY DIVIDING THE TOTAL SEEDS GERMINATED IN THE CONTROL AND MULTIPLY BY 100. DO THE SAME FOR THE COMPOST SAMPLES.

GERMINATION TEST IF THE GERMINATION RATE IS SIGNIFICANTLY LESS IN THE COMPOST SAMPLES, THE COMPOST IS LIKELY IMMATURE AND NEEDS FURTHER CURING.

SolvitaTests Solvitameasures two compounds, carbon dioxide (CO2) and ammonia (NH3), which are often connected to volatile compost emissions and can be a predictor of instability.

Solvitatests SOLVITA MATURITY TEST: The Solvitatest measures respiration and ammonia evolution in a specified volume of compost and gives a semi-quantitative color response accurate over a very wide range of CO2 and NH3 levels. The SolvitaMaturity Index is derived from both the CO2 rate and the volatile ammonia result Source: Woods End Laboratories

SolvitaTest Take a sample of compost by filling the test jar to volume Insert the Solvitaprobes and seal the container. Allow the container to rest for 4 hours. Read the compost maturity test results by comparing the probe color to the color chart

SOLVITA MATURITY INDEX MAJOR CLASSES 8 Highly matured, well aged compost, for all uses- FINISHED 7 Well matured compost, cured, ready for most uses COMPOST 6 Compost finishing curing; eradyfor some uses 5 Curing can be started; limited uses 4 Compost in moderately active stage 3 Very active compost; not read for most uses 2 Very active, fresh compost odorous - RAW 1 Fresh, raw compost; extremely unstable Source: Woods End Laboratories.

TROUBLESHOOTING PROBLEMS

Symptom: Pile is wet and smells like a mixture of rancid butter, vinegar, and rotten eggs Problem: Not enough air, OR too much nitrogen, OR too wet Solution: Turn pile Mix in straw, sawdust, or wood chips Turn pile and add straw, sawdust, or wood chips Provide drainage Source :Sam Angima Oregon State University Lincoln County Oregon

Symptom: Pile is damp and sweet smelling but will not heat up Problem: Not enough Nitrogen Solution: Mix in grass clippings, food scraps, or other sources of nitrogen Source :Sam Angima Oregon State University Lincoln County Oregon

Symptom: Pile does not heat up Problem: Pile is too small or too dry Solution: Make pile larger or provide insulation Add water while turning the pile Source :Sam Angima Oregon State University Lincoln County Oregon

Symptom: Pile is attracting animals Problem: Meat and other animal products have been included, or food scraps not well covered Solution: Keep meat and other animal products out of the pile; enclose pile in 1/4-inch hardware cloth Cover all food with brown materials such as leaves, wood chips, or finished compost

Symptom: Large, undecomposed items are still in the mix Problem: Not enough surface area Solution: Remove items, and chop or shred large items Screen and return undecomposed materials to a new batch to compost

Symptom: Compost is damp and only warm in the middle Problem: Pile is too small Solution: Collect more materials and mix the old ingredients into a new pile For effective critical mass, compost volume of 1 cubic yard is ideal but remember it does not have to be that to compost