THE WOODS END REPORT: Analysis of Commercial Bag Compost Products Organic Gardening Magazine
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
THE WOODS END REPORT:
Analysis of Commercial
Bag Compost Products
Commissioned to:
Organic Gardening Magazine
Emmaus, PA
DISCLAIMER: The information provided in this report has been prepared
independent of any consultative or commercial interest in any of the named
compost companies. This is a work for hire and the information is released as
non-confidential and the information is copyright-free. No liability is assumed
by the lab or the publishers of this information, its accuracy or reliability.
THE WOODS END REPORT: Analysis of Commercial Bag Compost ProductsWOODS END REPORT 11.0 INTRODUCTION:
How do commercial composts vary with respect to basic scientific traits? The
following survey reports double-blind lab results for commercial bagged com-
post products collected by a third party from across the US - principally the
Northeast- during September 1998 and analyzed at Woods End Research
Laboratory in Mt Vernon, Maine in the fall of 1998.
Laboratory evaluations and analyses included the following: pH, salt, organic
content, Solvita maturity, total-nitrogen, moisture, odor and texture. Total
nitrogen was only tested on samples which had a declared N value on the
label.
2.0 TEST METHODS
Test methods are listed below.
REFERENCE OF ANALYTICAL PROCEDURES USED IN SURVEY
Physical Parameters Symbol or Unit METHOD
Solids- Moisture Content TS% EPA 160.3 †
Chemical Parameters
pH -logH EPA 150.1
Salinity (Conductivity) dS/m EPA 120.1
Volatile Solids VS EPA 160.4
Organic Matter (VS - TKN * .54) % OM modified after
EPA 160.4 / 2
Total Kjeldahl Nitrogen TKN EPA 351.3
Biological/Microbiological Parameters
Solvita Test 0-8 TMECC #
Approved in; CA, TX,
FL, IL, ME, MN, NJ **
Organic Gardening Magazine WOODS END REPORT 23.0 SAMPLE SELECTION
LabKey Brand Names of Compost on Bag (Alphabetical Order only)
ID
X Bagged All American Compost
X Bagged Amish Way Composted Cow Manure
X Bagged Amish Way Composted Cow Manure Humus
X Bagged Back to Earth Cotton Burr Compost
X Bagged Black Gold
X Bagged Black Kow Composted Manure
X Bagged Chicken Manure Compost
X Bagged Compost+Manure
X Bagged Compostost Organic Compost
X Bagged EarthGrow Dehydrated Manure
X Bagged Farm Fresh Organic Horse Compost
X Bagged Fertil Manure Compost
X Bagged Garden Basics Composted Manure
X Bagged Garden Basics Cow Manure
X Bagged Garden Basics Organic Humus
X Bagged Gardeners Choice Organic Mushroom Compost
33 Bulk #33 Home Compost A
34 Bulk #34 Home Compost B
35 Bulk #35 Home Compost C
36 Bulk #36 Home Compost D
37 Bulk #37 Home Compost E
38 Bulk #38 Home Compost F
39 Bulk #39 Home Compost G
40 Bulk #40 Home Compost H
41 Bulk #41 Home Compost I
42 Bulk #42 Home Compost J
X Bagged Hyponex Organic Humus
X Bagged Intervale Organic Compost
X Bagged Mr Mushroom Compost
X Bagged New Era Dairyland Compost
X Bagged Organic Brands Mushroom Compost
X Bagged Organic Valley Cow Plus Organic
X Bagged ProBark Compost Soil Conditioner
X Bagged Real Stuff Organic Mushroom Compost
X Bagged Riverside Gardens Manure & Compost
X Bagged Riverside Gardens Sheep
X Bagged Scotts 3in1 Organic Compost Mix
X Bagged Southland Compost Mushroom Soil
X Bagged Stutzman Farms Chicken
X Bagged The Really Good Stuff Organic Compost
X Bagged All American Compost
X Bagged Amish Way Composted Cow Manure
Organic Gardening Magazine WOODS END REPORT 34.0 TEST RESULTS
Solv Total Labe
ID Moist Texture Odor pH Salt OM % ita N lN
1 ML Coarse Manure 7.1 7.7 14.0 8 - -
2 SAT Blobby - 7.2 2.2 31.0 8 - -
3 SAT B - 7.6 1.6 25.0 8 - -
4 H B Manure 7.6 1.3 22.0 8 - -
5 H B - 7.4 5.1 23.0 8 1.04 -
6 SAT B - 7.3 0.8 43.0 8 1.63 -
7 M F Woody 6.6 1.8 45.0 8 0.44 -
8 MH B M 6.9 1.3 15.0 8 0.71 -
9 VL Fine M 6.9 2.9 75.0 5 3.66 -
10 M F M 8.3 1.0 21.0 6 0.82 -
11 ML F,Wood M 7.8 3.0 49.0 6 - -
12 M F - 6.1 1.2 57.0 7 - -
13 M F,Grty Menthol 6.9 1.0 20.0 8 - -
14 M F,G Menthol 6.8 1.7 18.0 8 0.15 -
15 ML F - 6.9 19.7 34.0 7 1.74 -
16 L C - 5.9 4.7 11.0 8 -
17 H F Ammon 7.6 2.4 16.0 8 1.46 -
18 H F - 7.3 3.9 7.5 8 - -
19 MH F - 7.8 1.7 22.0 7 - -
20 ML F,W - 8.6 13.9 62.0 6 - -
21 M F,W - 4.5 3.9 85.0 8 - -
22 M F,W - 5.1 1.4 45.0 8 0.46 -
23 ML F,W - 6.9 3.2 20.0 6 1.05 -
24 M F - 6.8 3.5 21.0 8 0.83 -
25 ML F - 8.3 2.3 26.0 8 1.35 -
26 MH W - 5.5 1.1 92.0 8 - -
27 SAT B - 7.9 2.3 33.0 6 - -
28 SAT B - 7.5 10.2 28.0 7 - -
29 SAT B - 7.6 3.9 45.0 8 - -
30 H C - 7.4 4.2 49.0 6 - -
31 MH F - 7.4 10.5 32.0 8 - -
32 M F - 7.1 11.9 33.0 8 - -
33 MH F - 7.4 0.9 37.0 7 - -
34 SAT B Sour 7.6 2.1 24.0 8 - -
35 H F - 6.3 2.8 23.0 7 - -
36 M F,W - 7.7 2.0 30.0 7 - -
37 H F,W - 7.6 2.6 58.0 7 - -
38 M Soil,C - 7.1 6.9 17.0 7 - -
39 ML Soil,F - 7.1 4.3 25.0 7 - -
40 M S,C,W - 7.6 2.6 18.0 8 - -
41 ML S,C,W - 7.8 4.3 20.0 7 - -
Organic Gardening Magazine WOODS END REPORT 4Solv Total Labe
ID Moist Texture Odor pH Salt OM % ita N lN
42 H S,C,W - 6.6 4.6 24.0 8 -
- - Average (-) 7.13 4.06 33.2 7.4 1.18
5.0 SUMMARY OF ALL DATA
The data summarising the results of all 42 samples is:
ALL SAMPLES pH Salt OM % Solvita Total N
- MINIMUM 4.5 0.8 7.5 5 0.15
- MAXIMUM 8.6 19.7 92 8 3.66
- Average 7.13 4.06 33.2 7.4 1.18
Standard 0.82 3.94 19.4 0.8 0.89
Deviation
Variability 11% 97% 58% 11% 75%
6.0 BAGGED Vs/ GARDEN SAMPLES
The subset of garden (non-bagged samples) is seen below. The traits generally
vary less to significantly less than the bagged samples. These garden amples
would fit the category “Garden Compost” as specificed by the Woods End’s
QSAP program.
GARDEN SAMPLES pH Salt OM % Solvita Total N
- MINIMUM 6.3 0.9 17 7 -
- MAXIMUM 7.8 6.9 58 8 -
- Average 7.28 3.31 27.6 7.3 -
Standard 0.50 1.73 12.2 0.5 -
Deviation
Variability 7% 52% 44% 7% n/a
7.0 INTERPRETATION of DATA
(extracted from Woods Ends Laoratory Journal: For fill interpretation guideline see
www.woodsend.org/compost.htm)
pH: The pH must be interpreted in view of the origin and potential use of a ma-
terial. Lime treated wastes are likely to have moderately high pHs. The signif-
icance of pH is frequently underestimated. Ideally, the pH of any product, par-
Organic Gardening Magazine WOODS END REPORT 5ticularly compost, should be neutral to slightly acid (6.0 – 7.5) and efforts should be made to control it if it exceeds about 8.5. Lowering a high pH will help lower ammonia volatilization and reduce odors, as it will also favor a bal- anced microbial population. In other materials, such a potting soils, pH adjust- ment is important for reasons of plant growth. ORGANIC MATTER: Organic matter is reported in terms of total OM (weight loss on ignition minus total nitrogen). There is no absolute level of organic mat- ter which is ideal, rather the quantities must be viewed in relation to the age of a material, its nitrogen content, and its intended use. It is useful for purposes of composting to report the initial OM and contrast it with OM determined pe- riodically at later points. This gives an idea of the extent of decomposition. Or- ganic matter is often lower than expected because of incorporation of soil or sand. The OM test forms the basis for determining the sample’s C:N ratio (see later). Conversion to organic carbon is based on the factor OM x 0.54. NITROGEN: total-N: The quantity and form of nitrogen present in manure or compost is important in shaping the material’s quality. In the Woods End test we report the percent of total nitrogen. Concerning nitrogen release over the season, one should estimate this by considering the climate and the sam- ple’s intrinsic rate of decomposition (for example, as determined in our respi- ration test). Using either one of the two factors alone to judge the amount of nitrogen release may prove misleading. Our research indicates that nitrogen release from similar manures applied to the same soil may vary from as little as 20% up to 75% of total-N. CONDUCTIVITY (Salt Content): Soluble salt level (salinity) in a sample is estimated based on measurement of the electrical conductivity of a saturated paste. Components contributing most to salinity are sodium, potassium, chlo- ride, nitrate, sulfate, ammonia, and VOA. Low levels are expected for potting composts (
conductivity in the report is the traditional mmhos/cm, which is equivalent to
dS/m or dS m-1.
SOLVITA™ MATURITY TEST: The Solvita test measures total respiration in
a specified volume of compost and gives a semi-quantitative color response. The
test was developed as a field procedure to enable producers and uses of compost
to make on-the-spot stability and maturity determinations. The scale from 0 -
8 is seen in the following table:
Interpretation of Solvita Stability:
SOLVITA APPROXIMATE STAGE OF THE MAJOR
RESULT COMPOSTING PROCESS CLASS
8 Highly matured compost, well aged, possibly over-
aged, like soil; ready for most uses “FINISHED”
COMPOST
7 Well matured compost, cured, ready for most uses
6 Aeration needs are reduced; compost ready for curing;
significantly reduced management requirement
5 Past active phase of decomposition; curing can be
started; reduced need for intensive management “ACTIVE”
COMPOST
4 Compost in medium or moderately active stage
3 Active compost; young materials, still needs intensive
oversight and management
2 Very active, moderately fresh compost; high-respiration
rate; needs very intensive aeration and/or turning “RAW”
COMPOST
1 Fresh, raw compost; typical of new mixes; extremely
high rate of decomposition
Keys to Odor and Physical Rating Scale
KEY MEANING of TERM
MOISTURE:
ML Med-Low (i.e. fairly dry)
M Medium
MH Medium-High
H High - may be too wet
SAT Saturated - i.e. at or above water capacity
TEXTURE
B Blobby, sticky
F Fine
W Woody
Organic Gardening Magazine WOODS END REPORT 7KEY MEANING of TERM C Very Coarse Grty Gritty, as with gravel texture S Soil-like ODOR (-) neutral, non-odorous Sour garbage-acid Manure as in fresh cow manure M as in manure Menthol pungent like wood Ammon high ammonia vapors Organic Gardening Magazine WOODS END REPORT 8
Summary
The foregoing laboratory survey of commercial bagged composts reaveals a
wide variation of basic traits which were tested. Mosts composts were mature
to very mature; on a scale of 1-8, the average mnaturity was 7.4 with a devia-
tion of only 0.8. Only three samples out of 42 were rated immature by the Solvi-
ta test. In otherwords, the data set include mostly very aged products
pH ranged from a very acid 4.5 to strongly alkaline 8.6; the average was slight-
ly above neutral; the distribution show most samples clustered in a normal
range between 6.75 and 7.75.
With regard to salt (measured as conductivity) there were very large variations
of nearly 100%; the greatest clustering is in the normal range 1.5—2.5 mmhos/
cm. For the samples examined for nitrogen content we found 75% variation—
several bag labels that reported N gave incorrect numbers.
Organic content varied by about 60% with a clustering of samples in the medi-
um-low range of 15-19% OM. One-third of the samples smelled-poorly after re-
moving from bags. Thus, composts appeared to be very aged to over-aged and
generally on the wet side.
Conclusions
The data from the foregoing study reveal generally that bagged composts are
well to extremely well matured, and in conjuction with this contain moderately
low organic contents. Taken alone, these qualities would tend to support high
application rates by users. However, the great variance of other important test
traits such as salts and nitrogen content suggest use of the compost should be
more carefully controlled. The response of soil and plants is likely to vary wide-
ly from composts of this range if qualities.
The researchers tabulated lab traits and compared to label usage information
provided on the bags, indicating very little correlation. The report concludes
that compost users would be best off by experimenting first with composts to
Summary WOODS END REPORT 9determine their best use, or requesting more detailed information from the pro- ducers prior to purchase. The study recommends a simple slate of 5 tests be used to rate composts: pH, salt, organic matter, maturity and available nitro- gen. Conclusions WOODS END REPORT 10
You can also read
