Product Quality. Frank Franciosi Novozymes Nature s GREEN-RELEAF

Transcription

1 Product Quality Frank Franciosi Novozymes Nature s GREEN-RELEAF

2 Principle #1: Compost quality must be defined in relation to its use

3 Compost Good for One Use May Be Bad for Another, and Vice Versa Growing Media Topdressing/amendment PS: David Granatstein Mulch Erosion control

4 PS: BioCycle PS: Vermont Natural Ag Products

5 Relative Importance of Compost Quality Quality Measurement Greenhouse or Nursery Crops Target Compost Use Sales to General Public Soil amendment for fruit & vegetable crops Landscape Mulch Plant Growth Response High High High Low Nutrient content Low Medium Medium Low ph & soluble salts High High Medium Low Man-made inerts High High Medium Medium Sensory: color & odor Maturity & stability Medium High Low High High High Medium Low Particle size High Medium Medium Medium

6 What Determines Compost Quality? 1. Raw Materials (Feedstocks) Manure Sawdust Grass clippings Food Waste

7 Collect Feedstocks Collect Feedstocks 2. Composting Process Feedstock receipt Compost facility activities Non-compostables Recycle or dispose Collect Feedstocks Monitoring Feedstock preparation, mixing Active Composting 1 st Stage 2nd Stage Curing Odor control Water management Overs Dust control Product analysis Screening Storage and packing Recycle or dispose? Product sales, distribution and use

8 Why Test Compost? Regulations require it Environmental health and safety Customers want or need it Avoid problems Meet specifications Understand the process

9 How Do We Test For Quality? Take a representative sample Analysis only as good as the sample! Send to a reputable laboratory for testing List of compost labs:

10 Composite Sample Random cut-outs At least 15 similarsized sub-samples

11 Measuring Compost Quality What do we want to know? Is the compost done? Is the compost safe? What are its characteristics?

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15 Maturity and Stability Critical for horticultural applications, bagged product, and disease suppression Purposes of maturity measurements Evaluate success of composting process Comply with minimum product standards by users 15

16 Compost Stability Biological Stability Measurement of microbial activity How to Measure Respirometry testing Carbon dioxide evolution (CO 2 ) Oxygen uptake (O 2 ) Dewar 16

17 TMECC Method: CO 2 Evolution 17

18 CO 2 -C RATING GENERAL CHARACTERISTICS 1 very stable 2 4 stable > 11 moderately unstable unstable raw compost raw compost, raw organic products raw feedstock, unstabilized material well cured, finished compost no continued decomposition no odors moderately well cured compost odor production not likely curing compost odor production not likely aeration requirement reduced some odor production high aeration requirement moderate to high potential for VFA phytotoxicity odor production likely high aeration requirement high potential for VFA phytotoxicity and odor high potential for negative impact on soil carbon and nitrogen dynamics odor production expected probable VFA phytotoxicity with most materials negative impact on soil carbon and nitrogen dynamics expected

19 Respirometry Interferences Respirometry tests are performed on well aerated samples with balanced nutrient status Excessive salts or heavy metals can inhibit activity Excessively low (<35%) or high moisture (>50%, wet weight basis) High ammonia (> 500 ppm) can inhibit microbial activity High carbonates in compost can artificially inflate readings

20 Compost Maturity Degree of completeness of composting Immature composts can have: Free ammonia Volatile organic acids Immature composts can be phytotoxic Measure maturity with bioassays Z-Test (Earthworm) Cucumber seedling emergence & vigor

21 Compost Maturity: Bioassay

22 Cucumber Bioassay Tests for Phytotoxicity Phytotoxins include: Plant pathogens Free ammonia Herbicides Mature condition Emergence 80% of control Vigor 80% of control

23 Compost Maturity Bioassay Results

24 Bioassay Interferences High boron (B) concentration >50 ppm can be phytotoxic Excessively high salts relative to plant nutrients, specifically with cress and radish seed Sodium (Na) or chloride (Cl) relative to potassium (K), phosphorus (P) and nitrogen (N)

25 Other Maturity Indicators Temperature and reheating (decrease/time) Oxygen demand (decrease/time) C:N ratio Ammonia (decrease/time) or nitrate (low) Sensory: color, particle size and odor

26 Determine C:N Ratio as described in TMECC A Compost Maturity Index C:N Ratio is equal to or less than 25:1 Yes Test at least One Group A and One Group B Parameter (Table G2) Group A Group B No Evaluate Maturity Indicator Test Result (Table G4) Evaluate Stability Test Result (Table G3) Immature Assign Maturity Rating (Table G5) Very Mature Mature

27 Table G5

28 TMECC Maturity Index VERY MATURE MATURE IMMATURE Well cured compost No continued decomposition No toxicity potential No impact on plant-available soil nitrogen Cured compost Odor production not likely Limited toxicity potential Minimal impact on plant-available soil nitrogen Uncured or raw compost Odor production likely High toxicity potential Significant impact on plant-available soil nitrogen

29 Measuring Compost Quality What do we want to know? Is the compost done? Is the compost safe? For people and plants? Does it have limitations? What are its benefits? How can I use it?

30 Environmental Health and Safety

31 Pathogens Fecal coliforms and Salmonella are species of bacteria tested to determine if both human and plant pathogens have been reduced to safe levels Fecal coliforms < 1000 MPN/g Salmonella < 3 MPN/4g

32 Fecal Coliforms Are everywhere Occur at much higher concentrations than pathogens If <1000 MPN/g, pathogens are well below problematic concentrations If they are well distributed, pathogens are not

33 How Does Bacterial Regrowth Occur? During curing, remnant fecal coliforms can regrow as pile cools (if readily available carbon is abundant) Trommel screening can cause burst of bacterial growth by mixing bacteria, available carbon and moisture Birds, burrowing animals, contaminated water

34 Metals and Inerts Metals EPA 503 metals Inerts Metal fragments Glass Plastic

35 EPA 503 Metals (from SCL, n=3659) 503 limits Average Arsenic Cadmium Chromium* 1200* 30 Copper Lead Mercury Molybdenum 4.21 Nickel Selenium Zinc 2800

36 Sources of EPA 503 Metals Treated lumber (copper, arsenic, chromium) Batteries (lead, cadmium, zinc) Tires and fishing weights (lead) Metal fragments sized < 4mm (various) Painted wood (lead)

37 Metal, Glass, Plastic Fragments Metals: safety issue due to possibly being sharp and of unknown composition Sources: trash, demolition materials, weights, medical waste Glass: safety issue due to being sharp Sources: trash, demolition materials Plastic (non-compostable): Hurts the eyes purely an aesthetic issue Total Inerts (Metal + Glass + Plastic ) < 1.0 % by wt.

38 Compost Phytotoxicity Problems Due to fermentation in immature, high C/N materials Anaerobic limited aeration in overly large or wet pile Sour bark, sweet or sour odor Ammonium toxicity from immature low C/N materials Composted manure, food waste, sewage sludge Ammonia odor More severe in infertile, low CEC soils or potting mixes Soluble salts Excessively high sodium or chloride Very high ammonium

39 Plant Health and Safety

40 Fermentation-induced phytotoxicity caused mostly by acetic acid in composted mulch

41 Ammonium Toxicity Caused by Composted Manure in Low CEC Soil

42 Soluble Salts K + Mg 2+ Na + NH 4 + Ca 2+ Cl 2 SO 4 NO 3 CO 2 3 HCO 3 Measured by electrical conductivity Presence of soluble ions in solution (not all though) How well does a compost extract or slurry conduct electricity? Reported as either Deci Siemens per meter (ds/m), or Millimhos per centimeter (mmhos/cm)

43 Soluble Salts High salt content can affect seed germination and root health Excess soluble salts are phytotoxic Crops and plants differ widely in salt tolerance Composts usually < 10 and often <2.5 ds/m Typical soil levels < 1.5 ds/m

44 Leaching Continue curing If high ammonium Dilution, changing recipe Must know specific ions to balance Use as fertilizer If high in Potassium and low in Na and Cl

45 Weed Seeds Measured with germination test WHAT DO WEEDS INDICATE?

46 Herbicide Residues 48

47 Herbicide Residues Fortunately, most herbicides are short-lived Re-emerging issue: pyridine carboxylic acids Clopyralid, Aminopyralid, Aminocyclopyrachlor, others Dow: Stinger, Confront DuPont: Imprelis Used to control broadleaf weeds Clop: Effective at 3 parts per billion; after 18 months in compost pile Simple bioassay can detect possible contamination

48 Measuring Compost Quality What do you want to know? Is the compost stable and mature? Is the compost safe to use? Does it have limitations? What are compost s beneficial qualities? Physical Chemical Biological

49 Testing Compost Qualities Physical parameters Moisture content Bulk density Water-holding capacity Particle size

50 Physical Parameters May fluctuate widely Moisture Content Most often expressed as % of total weight If M.C. < 35% - very dusty, hard to handle, may not be mature If M.C. > 60% - very clumpy, heavy

51 Physical Parameters Bulk Density Affected by moisture content, ash content, particle size distribution & degree of decomposition To convert from weight to volume basis B.D. dry important in growing media As B.D. dry increases, porosity is reduced and water-holding capacity increases

52 Physical Parameters Water Holding Capacity Amount of water held in pores after gravitational loss for a period of time Amount held in compost after 4 hrs of free drainage Important for use in container mixes and potting soils

53 Physical Parameters Particle Size Turf applications (topdressing, etc.) Equipment used must pass ¼ particle size Where rapid drainage is important Growing media, golf courses, sediment filter systems

54 Chemical parameters Nutrients C:N CEC ph Testing Compost Qualities Nitrogen, Phosphorous, Potassium, Minor and Trace Elements Liming potential/buffering capacity

55 Testing Compost Qualities Biological parameters Organic Matter Microbial Analysis Disease supressiveness

56 Bacteria Fungi Actinomycetes Pseudomonads

57 Biological Parameters: Beneficial Microorganisms Frontier of understanding compost Soil Food Web Bacterially vs. Fungally-dominated Bacterial for rapid turnover, annuals Fungal for perennials and woody plants

58 If it isn t STA Compost...What is it??

59 Seal of Testing Assurance (STA) Program WHAT IS IT? Compost testing and information disclosure program (employing standardized practices) PURPOSE To assist compost end users purchase the product they require for their particular project To assure that compost end users know the characteristics of the compost products they purchase To improve overall customer confidence in compost selection and utilization

60 Meeting Overall Program Goals STA Composters will: Complete on-going product testing (operate on-going sampling/testing regime, sampling methods) Disclose test data results (lab analyses) Provide appropriate end use instructions Use uniform product label * Treat compost like any other retail, horticultural, agricultural product marketed in the U.S.

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62 Seal of Testing Assurance Program If it isn t STA Compost what is it? Consider Joining Contact: Al Rattie Al.rattie@compostingcouncil.org Visit USCC website at:

63 Compost Quality Recap Which quality parameters are most important?