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Page 1
Ozone
Crops
August 14, 2002
National Organic Standards Board Technical Advisory Panel Review
Page 1 of 1
Compiled by OMRI for the USDA National Organic Program
1
Executive Summary
2
3
Ozone was petitioned for use as a gas that is injected into soil under plastic mulch for weed control. An additional request
4
was made for use as an antimicrobial agent to clean irrigation lines. Ozone may also be used to treat soil for soil borne
5
pathogens, and this was also considered in this review. In all these types of use ozone gas (O
3
) is generated on-site using
6
an electrically powered corona discharge ozone generator.
7
8
Ozone is a bluish explosive gas or blue liquid. It is found naturally in the atmosphere at sea level contains an ozone
9
concentration at very low levels, but is also an air pollutant and a component of smog, reaching tenfold or higher levels in
10
cities at times. Although it is a pollutant and health hazard in the lower atmosphere, naturally occurring ozone is produced
11
in the outer atmosphere by the photoreaction of solar ultraviolet (UV) radiation on oxygen protecting the earth from
12
excessive radiation.
13
14
Ozone decomposes spontaneously in water and is a very reactive oxidizing agent with a short half-life. It is used to
15
disinfect water and to oxidize color and taste contaminants in water. It is also increasingly used for disinfection purposes
16
of food and food contact surfaces and is permitted by the National Organic Standards for use in organic processing
17
(including post harvest handling) with no restrictions.
18
19
Two reviewers felt that ozone should be permitted for use in organic crop production, though limited to use for cleaning
20
irrigation lines, weed control and for soilborne pathogen control. One of the reviewers in favor of use found that this type
21
of usage is a relatively new technique with unreliable results for pathogen control, and noted some reservations regarding
22
possible surface crusting and loss of soil structure when used for weed control. One reviewer objected strongly to use of a
23
“a known and problematic air pollutant” in organic farming and described hazards to workers and those downwind of
24
application, negative impact on soil humic acid fraction, plant damage, and lack of evidence of effect on soil
25
microorganisms. This reviewer did not object to use to treat irrigation water when ozone can be recaptured to prevent off-
26
gassing into the environment.
27
28
Summary of TAP Reviewer’s Analyses
1
29
30
31
Synthetic/
Nonsynthetic
Allow without
restrictions?
Allow only with
restrictions?
Synthetic (3-0) No (3)
Yes (0)
Yes (2)
No (1)
32
Identification
33
1
This Technical Advisory Panel (TAP) review is based on the information available as of the date of this review. This review addresses the requirements of the Organic Foods
Production Act to the best of the investigator’s ability, and has been reviewed by experts on the TAP. The substance is evaluated against the criteria found in section 2119(m) of the
OFPA [7 USC 6517(m)]. The information and advice presented to the NOSB is based on the technical evaluation against that criteria, and does not incorporate commercial
availability, socio-economic impact, or other factors that the NOSB and the USDA may want to consider in making decisions.
34
Chemical Names: Ozone, triatomic oxygen, O
3
35
36
Other Name: Trioxygen
37
38
Trade Names: SoilZone, Triox
39
40
CAS Number: 100028-15-6
41
42
Other Codes:
43
NIOSH RTECS #RS8225000
44
45
Characterization
46
47
Composition:
48
Ozone (O
3
) is triatomic oxygen.
49

Page 2
NOSB TAP Review Compiled by OMRI
Ozone
Crops
August 14, 2002
Page 2 of 18
50
Properties:
51
Ozone is a bluish, explosive gas or blue liquid. It has a characteristic pungent odor that is detectable at concentrations as
52
low as 0.02 to 0.05 ppm. At greater concentrations it is irritating to eyes and the respiratory tract and at high
53
concentrations ozone may be fatal. It is a strong oxidizing agent, mp –193
o
C, bp –111.9
o
C. It is sparingly soluble in
54
water. At 20
o
C, solubility of 100 percent ozone is 570mg/L (Richardson, 1994).
55
56
Atmosphere at sea level contains an ozone concentration of about 0.05 ppm (Budavari, 1996). In cities with smog
57
conditions ozone concentration may reach 0.5 ppm or higher at times. (Francis, 1997) Ozone decomposes spontaneously
58
in water (US EPA, 1999). The reaction generates hydroxyl free radicals, which are very reactive oxidizing agents but have
59
a half-life of microseconds. In aqueous solution, ozone can react by direct oxidation of compounds or can oxidize
60
compounds by hydroxyl free radicals that are produced during ozone decomposition.
61
62
How Made:
63
Ozone is usually formed by combining an oxygen molecule with an oxygen atom in an endothermic reaction. Naturally occurring
64
ozone is produced in the outer atmosphere by the photoreaction of solar ultraviolet (UV) radiation on oxygen. At ground level,
65
ozone may be produced by reactions caused by changes in entropy, e.g. water falling on rocks in a waterfall. Ozone is also
66
produced by photoreactions with nitrogen oxides (NO
x
) and volatile organic compounds (VOC) from industrial emissions,
67
vehicles and other sources (US EPA, 1999).
68
69
Because ozone is unstable it is generated at the point of use. It can be generated by irradiating oxygen-containing gas with UV
70
light and other technologies but the primary industrial method is by the corona discharge method. The oxygen containing gas is
71
passed through two electrodes separated by a dielectric and a discharge gap. When voltage is applied to the electrodes, electrons
72
flow across the gap and provide energy for the disassociation of oxygen molecules, which leads to the formation of ozone (US
73
EPA, 1999).
74
75
There are generally four system components to an ozone generating process: a power source or ozone generator, a gas source, an
76
ozone delivery system and an off-gas destruction system. The gas source may be air, high purity oxygen or a combination of the
77
two (US EPA, 1999). Air feed systems are more complicated than liquid oxygen feed systems because the air must be clean, dry,
78
free of contaminants and with a maximum dew point of -60
o
C to prevent damage to the generator.
79
80
Specific Uses:
81
Ozone has been used in Europe to treat drinking water for more than 100 years (US EPA, 1999). Ozone in the United
82
States has been used to disinfect water and to oxidize color and taste contaminants in water. It is increasingly used for
83
disinfection purposes.
84
85
The petitioned use is for the use of ozone for weed control (Pryor 2001) with an additional request for use as an
86
antimicrobial agent to clean irrigation lines as an alternative to chlorine (Herman 2002). In addition, the use of ozone for
87
control of soil borne pathogens will be considered in this review. In all these types of use ozone would be generated on
88
site.
89
90
Ozone gas for weed control is used in combination with plastic mulch and is applied in a gaseous form. The target
91
treatment area is the space between the plastic mulch and either the drip irrigation tubing if it is buried or the soil surface
92
if drip tubing is not buried. Ozone is applied under the mulch before the crop is planted. It has also been applied once
93
the crop is in place (Pryor, 1999; Pryor, 2001). It may be applied through drip tape, which can later be used for crop
94
irrigation. Ozone oxidizes plant tissue and weakens or kills emerging weeds. Ozone treatment for weed control may be
95
used in combination with soil solarization. As described in the petition, ozone for weed control may be applied at rates of
96
2 lbs/acre with a total number of applications ranging from 7-30 depending on weed species.
97
98
Ozone uses for control of soil borne pathogens has been tested at rates ranging from 50-400 lbs per acre (Pryor, 1999). It
99
can be applied through drip tubing under plastic mulch or by various methods of direct injection (Pryor 1996, 1997).
100
101
Ozone can be used to treat or prevent clogged drip irrigation systems by at least two methods. Recycled irrigation water
102
can be treated with ozone before reuse. (NIDO, 1997) A requested additional use is to inject ozone into the irrigation
103
lines to act as an antimicrobial agent (Herman 2002). This seems to be a fairly new use with little information to describe
104
the method. One industry writer reports that the gas is generated on site in a closed system and dissolved in water under
105
pressure, and that undissolved gas is collected and disposed of by means of a special separator to avoid accumulation of
106
gas bubbles in the system (Hassan, undated).
107
108
109
110

Page 3
NOSB TAP Review Compiled by OMRI
Ozone
Crops
August 14, 2002
Page 3 of 18
Action:
111
Ozone is a strong oxidizing agent and very corrosive. In plants, it can cause membrane lysis and necrotic lesions. It may
112
affect photosynthesis and generally represses various genes (Sandermann, 1996). It is germicidal against a wide range of
113
organisms including bacteria, viruses and protozoa. In bacteria, it attacks the bacterial membrane, disrupts enzymes and
114
affects nucleic acids (EPA, 1999). In viruses, ozone modifies the viral capsid and may break the protein.
115
116
Combinations:
117
Not sold in combinations.
118
119
Status
120
121
Historic Use:
122
Historically ozone has been used to disinfest and oxidize pathogens and contaminants from drinking water. It was first
123
used in the Netherlands in 1893. Ozone was used in Los Angeles, California in 1987 to treat drinking water and by 1998,
124
264 water treatment plants in the U.S. were using ozone (US EPA, 1999). Since the implementation of the Surface Water
125
Treatment Rule the use of ozone for primary disinfection of water has increased (EPA, 1999). Use as a soil treatment to
126
kill living organisms is a relatively recent invention (Pryor, 1996).
127
128
OFPA, USDA Final Rule:
129
Ozone is listed for use in post-harvest handling and processing (7 CFR 205.605(b)(20). It could be considered a
130
production aid under 7 USC 6518(c)(1)(B)(i).
131
132
Regulatory: EPA/NIEHS/Other Sources
133
The EPA sets standards for ozone levels under the National Ambient Air Quality Standards as required by the Federal
134
Clean Air Act. EPA considers ozone producing equipment to be ‘pesticidal devices.’ Ozone generation is subject to
135
pesticide worker safety requirements (40 CFR 170).
136
137
Ozone is subject to the National Primary Drinking Water Regulations under the Safe Drinking Water Act because it is
138
used as a disinfectant in water treatment to kill pathogens. (40CFR 141.65)
139
140
FDA considers ozone to be GRAS as a direct food additive and allows the use of ozone as an antimicrobial agent for
141
bottled water and food processing (21 CFR 184.1563). Bottled water maximum residual permitted ozone level is 0.4 mg/l
142
at bottling.
143
144
OSHA: 29 CFR 1910.1000 Subpart Z
145
Transitional Limit: PEL-TWA 0.1 ppm
146
Final Limit: PEL-TWA 0.1 ppm; STEL 0.3 ppm
147
ACGIH: TLV-Ceiling Limit 0.1 ppm
148
NIOSH Criteria Document: None
149
NFPA Hazard Rating: Health (H): None
150
Flammability (F): None
151
Reactivity (R): None
152
153
154
Status Among U.S. Certifiers
155
California Certified Organic Farmers (CCOF) –CCOF Certification Handbook (rev. January 2000). Not specifically listed.
156
Maine Organic Farmers and Gardeners Association (MOFGA) –MOFGA Organic Certification Standards 2001. Not specifically
157
listed.
158
Midwest Organic Services Association (MOSA) –MOSA Standards January 2001. Not specifically listed.
159
Northeast Organic Farming Association of New Jersey (NOFA-NJ) – NOFA-NJ 2000 Organic Certification Standards. Not
160
specifically listed.
161
Northeast Organic Farming Association of Vermont (NOFA-VT) – 2001 VOF Standards. Not specifically listed.
162
Oregon Tilth Certified Organic (OTCO) – OTCO Generic Materials List (April 30, 1999). Not specifically listed.
163
Organic Crop Improvement Association International (OCIA) –OCIA International Certification Standards, July 2001. Not
164
specifically listed.
165
Quality Assurance International (QAI) – QAI Program, Section 5.2 Acceptable and Prohibited Materials. Not specifically
166
listed.
167

Page 4
NOSB TAP Review Compiled by OMRI
Ozone
Crops
August 14, 2002
Page 4 of 18
Texas Department of Agriculture (TDA) Organic Certification Program – TDA Organic Certification Program Materials List. Not
168
specifically listed.
169
Washington State Department of Agriculture Organic Food Program – Chapter 16-154 WAC Organic Crop Production Standards.
170
Not specifically listed.
171
172
International
173
CODEX – Not specifically listed.
174
EU 2092/91 – Not specifically listed.
175
IFOAM – Not specifically listed.
176
Canada – Not specifically listed.
177
Japan – Not specifically listed.
178
179
Section 2119 OFPA U.S.C. 6518(m)(1-7) Criteria
180
181
1. The potential of the substance for detrimental chemical interactions with other materials used in organic farming systems.
182
As a strong oxidizing agent, ozone has the potential to react with many different substances. Ozone oxidizes
183
pesticides, organic matter, and reacts with iron and most other materials. Ozonation of water produces various by-
184
products such as aldehydes, ketones, carboxylic acids, organic peroxides, epoxides, nitrosamines, N-oxy compounds,
185
quininones, hydroxylated aromatic compounds, brominated organics and bromite ion. (Kirk-Othmer, 1996)
186
187
When ozone is used for weed control, it is applied directly to the space between the buried drip irrigation tubing or
188
the soil and the plastic mulch. It is not clear how much ozone diffuses into the soil in this system but Qui, et al.
189
(2001) found that the ozone mass transfer rate was influenced by soil moisture and texture. An early study found that
190
ozone applied as gas at 0.5 ppm did not penetrate the soil to a statistically significant extent (Blum and Tingey, 1977).
191
More recent work examined the effect of ozone on soil organic matter when ozone is used to decontaminate soil . In
192
a system where a soil extract was ozonated, researchers found a decrease in the humic acid fraction, a reduction of the
193
average molecular size, and an increase in the low molecular acid fraction. The low molecular acid fraction is readily
194
degradable by microorganisms (Ohlenbusch et al., 1998).
195
196
In lab studies ozone caused reduction in respiration rates of ectomycorrhizal fungal mats. However when these fungi
197
were associated with their host plant roots the ectomycorrhizal roots were more resistant to ozone than non-
198
ectomycorrhizal roots (Garret et al., 1982). In laboratory studies soil nematode populations of Meloidogyne javanica
199
and free living nematodes were significantly reduced by ozone treatment and were dosage and flow rate dependent
200
(Qui et al., 2001). In other research, ozone treatment of Easter lily bulbs did not reduce nematode numbers (Giraud
201
et al., 2001) although it did give a positive yield response. In field experiments with tomatoes, Pryor (2001b) found
202
that ozone treatments did not significantly reduce nematode populations, but may have led to increased yields in
203
some cases.
204
205
Ozone is used for water treatment because it oxidizes or disinfects many components that impact water quality. It
206
will oxidize iron and manganese which precipitate as ferric and manganese hydroxides. This could result in crop iron
207
deficiencies (von Broembsen, 2002.). It partially oxidizes organic matter to forms that are more easily biodegradable.
208
Ozone is also germicidal against many types of pathogenic organisms including viruses, bacteria and protozoa (US
209
EPA, 1999). Ozone itself does not remain as a residual in irrigation water because of its rapid decomposition. It does
210
form a variety of byproducts in reaction with organic matter. It can also react with the bromide ion if present to form
211
brominated disinfection byproducts (US EPA, 1999). The ozone will most likely oxidize any materials that a grower
212
injects into the irrigation lines at the same time as the ozone. For example, if growers inject fertilizer such as fish
213
emulsion or other material into the irrigation system, ozone will oxidize the material. The extent would depend on the
214
concentration of the added material, the concentration of the ozone and the contact time.
215
216
2. The toxicity and mode of action of the substance and of its breakdown products or any contaminants, and their persistence and areas of
217
concentration in the environment.
218
Ozone is a strong oxidant and is inherently bioreactive. Given its reactivity and relative concentration, it is the oxidant
219
of primary concern in photochemical smog (Klaasen, 2001).
220
221
Ozone is rated as a high irritant via inhalation and to skin, eyes and mucous membranes. It also affects the central
222
nervous system and there are mutation data and reproductive concerns. (NTP 2002, NJ 1996) Higher exposure can
223
cause headache, upset stomach, vomiting, and pain or tightness in the chest. Ozone can irritate the lungs causing
224
coughing and/or shortness of breath. Higher exposures can cause a build-up of fluid in the lungs (pulmonary edema),
225
with severe shortness of breath. Liquefied ozone on contact with skin or eyes can produce severe burns. There is
226

Page 5
NOSB TAP Review Compiled by OMRI
Ozone
Crops
August 14, 2002
Page 5 of 18
limited evidence that ozone causes cancer in animals. It may cause cancer of the lung, mutations (genetic changes) and
227
may damage the developing fetus. (NJ 1996, Richardson 1994)
228
229
230
NTP Toxicity
Type of
dose
mode
specie amount
units
LC50
ihl
cat
34,500 ppb/3H
LC50
ihl
gpg
24,800 ppb/3H
LC50
ihl
ham
10,500 ppb/4H
LCLo
ihl
hmn
50,000 ppb/0.5 H
TCLo
ihl
hmn
100,000 ppb/0.016 H
TCLo
ihl
hmn
1,000
ppb
Source: NTP, 2001
Abbreviations
231
LC50 = lethal concentration 50 percent kill
232
LCL = lowest published lethal concentration
233
TCL = lowest published toxic concentration
234
H = hour
235
ihl = inhalation hmn = human gpg = guinea pig ham = hamster
236
237
Eco Toxicity (Richardson 1994):
238
Fish – LC 50 (96 hr) rainbow trout 9.3microg/l,
239
LC 50 (24 hr) bluegill sunfish 0.06 mg/l
240
241
Invertebrate – Bacteria species showed change in phospholipid levels after 30 sec. aeration with 1mg/l. Euglena gracilis
242
had damaged plasma membranes. Enzyme deactivation in yeasts was found.
243
244
In plants, it can cause membrane lysis and necrotic lesions. It may affect photosynthesis and generally represses
245
various genes (Sandermann, 1996). It is germicidal against a wide range of organisms including bacteria, viruses and
246
protozoa. In bacteria, it attacks the bacterial membrane, disrupts enzymes and affects nucleic acids (US EPA, 1999).
247
In viruses, ozone modifies the viral capsid and may break the protein.
248
249
When ozone is applied beneath plastic mulch for weed control its mode of action is in part by direct oxidation. It is
250
taken up by the plant stomata where it is decomposed in the apoplast. Ozone effects chloroplast function and
251
nuclear gene expression by mechanisms that are not understood at this time. Membrane lysis is thought to be a later
252
effect of ozone (Sandermann, 1996). The ozone would also be in contact with soil. The amount of soil affected
253
depends in part on the depth of the placement of the drip irrigation lines. Ozone oxidizes the soil humic acid fraction
254
of organic matter (Ohlenbusch et al., 1998).
255
256
When ozone is applied under plastic the area of concentration is the zone between the drip irrigation tubing or soil
257
surface and plastic mulch. When ozone is in contact with organic materials such as plants, its half-life is a few
258
minutes. Potential concern would be for worker safety during the application of the ozone and any leaks in the
259
system. The half-life of ozone in ambient air is 12 hours (Pryor 2001). Ozone’s only decomposition product is
260
oxygen.
261
262
In water there are two modes of action by ozone, direct oxidation and oxidation by hydroxyl free radicals. It oxidizes
263
organic matter, attacks bacterial membranes, disrupts enzymatic activity, disassociates viral capsids and attacks RNA.
264
265
In water ozone decomposes rapidly and the only residual is dissolved oxygen. However decomposition by products
266
may be present. If the bromide ion is present in water brominated decomposition products may remain. Formation
267
of aldehydes has also been found as a result of ozone disinfection (Liberti and Notarnicola, 1999) Some of the
268
disinfectant by products are potentially toxic or carcinogenic, however bioassay screening studies have shown that
269
ozonated water induces substantially less mutagenicity than chlorinated water. (Kirk Othmer, 1996) Ozone does not
270
form halogenated by products (trihalomethanes) when reacting with natural organic matter in water, unless bromide
271
ion is present in the raw water. (US EPA 1999)
272
273
Disinfection and chemical oxidation rates by ozone are relatively independent of temperature (EPA, 1999). If
274
recirculated irrigation water is treated with ozone, the excess ozone must be scrubbed to prevent release to the
275
atmosphere and to protect workers from ozone exposure.
276
277

Page 6
NOSB TAP Review Compiled by OMRI
Ozone
Crops
August 14, 2002
Page 6 of 18
3. The probability of environmental contamination during manufacture, use, misuse, or disposal of the substance.
278
Ozone at ground level is considered a priority air pollutant by US EPA. Ozone would be generated on site both for
279
use in soil treatment and as an antimicrobial agent in irrigation systems. Ozone is not stored on site. Because ozone
280
is toxic care must be taken to avoid leaking of ozone from the system during generation. Levels of 1ppm for 30
281
minutes or more produce headaches. OSHA’s maximum permissible exposure level (PEL) to ozone is not to exceed
282
0.1 mg/L by volume averaged over an 8 hour period.
283
284
During water treatment ozone gas is transferred to water. In treating recycled irrigation water, ozone that is not
285
transferred to the water is released as off gas. The concentration of ozone in the off gas of these systems is above the
286
concentration fatal to humans and may contain as much as 3,000 ppm ozone (US EPA, 1999). Off gas containing
287
ozone should be captured and converted to oxygen before release into the atmosphere. Ozone systems that inject
288
directly into the irrigation lines use much lower concentrations of ozone and do not treat off gas.
289
290
4. The effects of the substance on human health.
291
Ground level ozone may reach levels that are harmful to human health. Most of the studies regarding ozone as a
292
threat to human health are related to ozone as an air pollutant generated by automobile exhaust and other fossil fuel
293
generated sources (US EPA, 1999).
294
295
Acute Toxicity. High concentrations above 0.1 mg/L by volume average over an 8 hour period may cause nausea,
296
chest pain, reduced visual acuity and pulmonary edema. Inhalation of > 20 ppm for at least an hour may be fatal.
297
298
Chronic effects. May have deleterious effects on the lungs and cause respiratory disease. See response to criterion
299
number 1.
300
301
5. The effects of the substance on biological and chemical interactions in the agroecosystem, including the physiological effects of the substance on
302
soil organisms (including the salt index and solubility of the soil), crops and livestock.
303
The effects are mainly the immediate result of ozone’s strong oxidizing capacity. Ozone is a broad-spectrum biocide
304
that can oxidize soil organic matter and other substances in soil (Ohlenbusch et al., 1998). Ozone does not persist in
305
soil with either the weed control or water treatment system application. It is converted to oxygen within a short
306
period of time. The issue is what, if any, are the remaining impacts of ozone use.
307
308
When ozone is used for weed control, the ozone is in contact with the soil, soil organic matter and microorganisms.
309
It has been shown in the laboratory that ozone can oxidize the soil humic acid fraction into lower molecular weight
310
fractions which are more biologically available to soil microorganisms (Olenbusch, 1998). This research found that
311
bacterial regrowth increased with ozonation time. The effects on the populations of other soil microorganisms were
312
not examined in this research.
313
314
Other research has shown that ozone does reduce populations of at least some other soil microorganisms such as
315
some nematodes while other nematodes appear unchanged (Qui et al., 2001 and Giraud et al., 2001). Soil injection at
316
250 lb/acre rate resulted in increases of yield of tomatoes comparable to chemical fumigants in one year, although it
317
did not statistically reduce root galling by nematodes. (Pryor 1999). Yield increases were theorized to have resulted
318
from other biological effects, possibly increase in nutrient availability. Conventional farmers use soil fumigation with
319
methyl bromide to achieve large increases in yield in crops such as carrots, tomatoes and strawberries although the
320
increases are not linked to specific elimination of known pathogens. A study of the populations of the different
321
strains of the fungi Fusarium in organic (treatments used cultural methods) and non-organic farming systems
322
(treatments used the fumigant Telone) found that the greatest number of pathogenic strains were recovered from the
323
organic farm, however no plants at the organic site showed any symptoms while plants on the conventional site did
324
show symptoms. In addition, the organic site was found to exhibit more than twice the number of non-pathogenic
325
strains of Fusarium which have been shown to reduce the incidence of Fusarium wilt (Bao, 2000).
326
327
The availability and form of soil organic matter affects a broad spectrum of soil chemical and microbiological
328
reactions. Soil organic matter influences cation exchange capacity, soil buffering, soil microorganism population
329
dynamics, and plant disease among other aspects of the soil environment (Brady, 1974, Engelhard, 1989).
330
331
If the crop is present when ozone is applied there can be physiological impacts such as burning on the crop (Pryor, 1999). It
332
appears that when plants are exposed to ozone it elicits plant responses that are similar to plant responses to pathogens.
333
These responses to ozone are just beginning to be understood (Sandermann, 1996). Ozone is a known air pollutant that
334
causes crop damage ( Mersie 1990, Hatzios 1983), and in event of a leak in application method can cause crop loss (Pryor
335
1999).
336
337

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NOSB TAP Review Compiled by OMRI
Ozone
Crops
August 14, 2002
Page 7 of 18
Ozone that is used to treat water before it is injected into the irrigation lines does not come in contact with the soil or crop
338
plants. The ozone off gas is recycled or converted to oxygen so that it is not released to the atmosphere. The reaction of
339
ozone with the bromide ion or organic matter that may be in the water can create decomposition by products. No
340
information was found on the potential impact of these on the soil environment when irrigation water is used. The
341
decomposition byproducts of ozone treatment appear to be of less concern than the decomposition byproducts of chlorine
342
treatment although brominated decomposition byproducts may be of health concern (von Broembsen. 2002, EPA, 1999,
343
Braghetta 1997).
344
345
When ozone is injected with water into irrigation lines to clean them, there is the potential that some ozone will move from
346
the irrigation lines to the soil or air. No information has been found that examined this question. In actual practice the
347
grower must monitor the system to determine that enough ozone has been injected to reach throughout the irrigation line
348
before it has been completely consumed by oxidation reactions.
349
350
6. The alternatives to using the substance in terms of practices or other available materials.
351
There are various weed control methods available to organic growers and in general growers need to use a variety of
352
techniques to achieve effective weed control. Some of the methods include: flame throwers, mulch, cultivation, water
353
management, bioherbicides, steam treatment and soil solarization (Smith et al., 2000 and Boyette et al., 1999).
354
355
Soil solarization is a technique that could be used alone or in conjunction with ozone or other material like cabbage
356
residue (Chellemi et al., 1997). It can be used both for weed and pathogen control. New heat-retentive films are
357
more effective at raising soil temperatures during solarization (Chase et al., 1999). Cyperus spp. (nutsedge) are
358
particularly difficult weeds to control. Recent research showed that soil temperature of 45
o
C was not lethal to Cyperus
359
spp. tubers (Chase, Sinclair and Locascio, 1999). Temperatures of 50 - 55
o
C were 100% lethal to tubers. The new
360
heat retentive films were more effective at killing Cyperus rotundus.
361
362
Alternatives for control of soil borne pathogens include crop rotation, solarization, use of disease suppressive
363
compost, other organic nitrogen amendments, biocontrol, and IPM methods. A recent compendium of a 2000 EPA
364
meeting report lists 117 papers on alternatives to methyl bromide, including many tests of biocontrols and cultural
365
methods (US EPA 1997, 2000; Bull 2000). One-year rotations out of strawberries increased subsequent strawberry
366
yields by 18-44% relative to continuous strawberries (Duniway 2000). Varieties more suited for organic production
367
are also identifiable, for instance the ‘Camarosa’ variety is significantly more susceptible to Verticillium than ‘Chandler’
368
or ‘Selva’ (Duniway, 2000.) Existing organic production techniques are considered to adequately control soil borne
369
pathogens, and result in slightly lower yields that are offset by higher prices (US EPA 1996). Use of strawberry plant
370
plugs rather than bare root resulted in earlier production, less transplant wounding, increased vigor and offset
371
problems from soil born pathogens (Sances, 2000.)
372
373
Current potential alternatives to the use of ozone as an antimicrobial in irrigation systems include chlorine, acetic acid,
374
and citric acid (OMRI, 2001). Ozone is a stronger oxidizing agent than all of these. Ozone by itself and in water does
375
not form trihalomethanes, which are carcinogenic (US EPA 1999) Chlorine treatment forms trihalomethanes.
376
377
If a grower wishes to removed pathogens and particulate from their water source, slow sand filtration would be an
378
alternative (Wohanka, 1995). Slow sand filtration is a water treatment system that has been used for more than 100
379
years. Untreated water filters slowly through a fine sand bed. A skin of organic and inorganic material and
380
microorganisms begins to form on the surface of the sand bed. The biological activity of this area extends through
381
the upper region of the bed. This method has been effective against several pathogens including Cylindrocladium spp.,
382
pythiaceaeous fungi, Verticillium dahliae and others (Wohanka, 1995).
383
384
There are certain situations where slow sand filtration would not be an alternative to ozone use. If a grower’s
385
irrigation lines are already clogged, sand filtration is not going to correct the situation. If a grower were applying a
386
fertilizer such as compost tea or fish emulsion through the irrigation lines, the sand filtration process would not clean
387
the irrigation lines or keep them from clogging due to biofouling. This is because the fertilizer would need to be
388
injected after the sand filtration step. Otherwise the sand filtration would remove the desired nutrient content. The
389
effectiveness of ozone injected into a drip irrigation system to prevent clogged emitters is not documented, and is
390
questionable due to the rapid decomposition of ozone in the aqueous environment into oxygen. No supporting
391
technical literature was found to substantiate this claim, it appears to be an experimental treatment.
392
393
7. Its compatibility with a system of sustainable agriculture.
394
To answer this question each use should be considered separately since the target organisms and methods and rates of
395
application are different. In addition the mode of transport for each use is different. For weed control, ozone is
396
injected into an air-water interface in the soil or on the soil surface. For use in cleaning of irrigation lines and water
397
treatment, ozone is injected into the water either before or as it enters the irrigation line. In general the impacts of the
398

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use of a material should be targeted rather than widespread. Potential non-target, unintended impacts need to be
399
considered.
400
401
Ozone for weed or soil borne pathogen is not selective with regard to the plant species that it kills. It is toxic to all
402
plants, however different species respond differently to the same dose of ozone (Hatzios and Yang, 1983, and
403
Sandermann, 1996). It is applied in a defined space, the area between the buried drip irrigation tubing or the soil
404
surface and the plastic mulch (Pryor, 1999). It is a very strong oxidant and will oxidize the soil surface that it
405
contacts. It can oxidize soil organic matter and make it more biologically available (Ohlenbusch et al., 1998). It is
406
unclear from the references found by the reviewer how deep ozone will diffuse into the soil under the conditions of
407
the proposed use. It was also unclear what concentration of ozone the weeds and soil would be exposed to. The
408
petitioner claims the impact will only reach 0.25 inches when applied at rates suitable for weed control. It is very
409
reactive, has a short half-life and does not leave a residual effect. It is destructive to a wide range of microorganisms
410
but not all (EPA, 1999; Giraud et al. 2001; and Qui et al., 2001).
411
412
The production of ozone from oxygen is due to an endothermic reaction, and requires a considerable input of energy.
413
The patent documents mention the presence of a generator on the apparatus (Pryor 1996, 1997) but does not
414
describe the power requirements needed, presumably supplied by diesel or gas engine. The EPA describes the voltage
415
requirements for an air-fed corona discharge system as 5-7 kilowatts/hour/pound of O
3
produced. As much as 85%
416
of the energy used in ozone production is lost as heat. (US EPA 1999)
417
418
When ozone is used to treat water it is reactive with a wide variety of chemicals and compounds in the water
419
including iron, manganese and organic matter. It is also germicidal against many microorganisms such as protozoan
420
cysts, viruses, and bacteria including E. coli 0157:H7 (EPA, 1999 and Unal et al., 2001). It is applied to water before
421
use in irrigation or directly injected into irrigation lines with irrigation water. When ozone is used treat water prior to
422
irrigation, ozone concentrations are higher than when it is injected into irrigation lines to prevent biofouling. In the
423
first instance, the system is enclosed and excess ozone is captured and recycled or converted to oxygen before it is
424
released to the atmosphere. Typical concentrations of ozone found during water treatment are from <0.1 to 1 mg/L
425
(EPA, 1999). When ozone is injected directly into the irrigation system, concentrations are lower. A potential
426
problem with the second system from a purification point of view is that the ozone may be completely consumed by
427
oxidation reactions with chemicals, microorganisms and organic materials in the line before it reaches the end of the
428
irrigation line. Excess ozone is not captured in this system.
429
430
431
Additional Questions for the reviewers:
432
Note: The initial petitioner only requested review for purposes of weed control, and did not respond to questions requesting
433
more information on other uses. NOSB advised that it also be reviewed for soil pathogen control.
434
435
1. Have you seen or can you find any specific mention of use of ozone injected in drip irrigation systems as a cleaning
436
agent?
437
2. Does anyone have access to this reference, and can you report on it:
438
Raub, L., Amrhein, C., and M. Matsumoto. 2001. The effects of ozonated irrigation water on soil physical and
439
chemical properties. Ozone Science and Engineering. 23(1):65-76
440
3. Do you have any additional evidence on impact of ozone on the soil ecosystem, short or long term?
441
4. Have you seen any information on the effect of ozone application on soil organic matter and nutrient availability.
442
5. Please express your technical review, advice and conclusions distinctly on each of these uses of ozone. Is it possible to
443
permit use for some purposes but not others? (e.g for weed control but not soil pathogens)
444
445
446
447
TAP Reviewer Discussion
448
449
Reviewer 1
[Ph.D. chemistry. Research entomologist advising growers and homeowners about pesticides and alternative pest control methods.
450
Western US]
451
452
OFPA Criteria Evaluation
453
454
(1) The potential of such substances for detrimental chemical interactions with other materials used in organic farming systems;
455
I agree with the criteria evaluation, with additional comment:
456
Since ozone is such a powerful oxidizing agent, it might attack the plastic irrigation tubing and destroy it over time.
457
Seems like plasticizers such as dioctylphthalate in tubing would be destroyed. However, this is speculation, and no
458
one seems to have observed this with limited ozone applications in the field.
459

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460
(2) The toxicity and mode of action of the substance and of its breakdown products or any contaminants, and their persistence and areas of
461
concentration in the environment;
462
I agree with the criteria evaluation.
463
464
(3) The probability of environmental contamination during manufacture, use, misuse or disposal of such substance;
465
I agree with the criteria evaluation, with additional comment:
466
The possibility of a problem increases with the size of the ozone generator. For soilborne pathogen control, amounts
467
generated and release volumes would be higher than with the other two applications, and thus might be riskier.
468
469
If the generator is set up properly, leaks in the ozone supply line, torn or compromised plastic sheeting, and the
470
possibility of fire are the only risks that I can think of.
471
472
(4) The effect of the substance on human health;
473
Ozone has actually been used in medicine. Amounts in plasma higher than 80 µg/ml of gas per ml of blood are
474
detrimental (Bocci et al. 2001).
475
476
(5) The effects of the substance on biological and chemical interactions in the agroecosystem, including the physiological effects of the substance on
477
soil organisms (including the salt index and solubility of the soil), crops and livestock;
478
479
Ozone seems to have very little effect on soil nematodes. It seems to have more of an effect on soil bacteria than soil
480
fungi. Treatment of strawberry fields with high rates of ozone improved colonization of Trichoderma when this
481
microbial was used subsequently as an inoculant, so there must have been either an initial knockback of competing
482
microbials or releases of nutrients favorable for Trichoderma sp. growth (Pryor 2001b).
483
484
(6) The alternatives to using the substance in terms of practices or other available materials; and
485
486
For nursery operations, steam is a practical alternative for management of pathogens. Suppressive composts are
487
especially valuable in containerized production. Crop rotation is probably the most practical alternative for field crops
488
(see Quarles and Daar 1996).
489
490
(7) Its compatibility with a system of sustainable agriculture.
491
492
One possible problem is destruction of soil organic matter. Raub et al. (2001) believed that oxidation of organic
493
matter on the soil surface could lead to surface crusting and loss of soil structure. They suggested longterm studies to
494
explore this possibility. Surface effects would be most likely with weed control. For weed and pathogen control there
495
are several applications throughout a 30-day period. Amounts applied for pathogen control are 10-fold or more
496
greater, but the ozone is applied about 3 inches deep, rather than directly on the surface. Cleaning of irrigation lines
497
should not lead to any problem with soil structure because most of the ozone would be contained in the irrigation
498
tubing.
499
500
Another consequence of ozonation could be release of copper ion, which is bound to organic matter. Lin et al. (2001)
501
found that ozonation of humic acids in water degraded them to smaller molecules that were unable to chelate copper
502
ion. In soils where Cu has been overapplied, ozonation could lead to phytotoxicity due to excess free copper.
503
504
RESPONSE TO ADDITIONAL QUESTIONS
505
(1) Have you seen or can you find any specific mention of use of ozone injected in drip irrigation systems as a cleaning agent?
506
I talked to [owner of a well known west coast organic farm supply company.] She has not heard of anyone cleaning
507
irrigation lines by direct injection of ozone. She has heard of farmers treating irrigation water with ozone before it is
508
applied to the irrigation system.
509
510
(2) Can you find and report on this reference?: Raub, L., Amrhein, C. and M. Matsumoto. 2001.
511
512
To check the effect of ozone on soil structure, Raub et al. (2001) applied ozonated water at 10mg/liter to 20 cm glass
513
columns containing various California soils. They found that the ozone reacted with the humic acids and other
514
organic material, degrading it to smaller molecules. Degradation of the organic matter released cations such as Ca+2.
515
The organic acids and cations lowered pH of the applied water and caused clay in the soil to coagulate. Coagulation of
516
the clay particles increased the water infiltration rate and allowed the soil columns to drain quicker. In soils with high
517
sodium content (>15%) the improved drainage was not observed.
518
519

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Positive results other than improved drainage was improved oxygenation, and probably increased microbial activity,
520
since the humic acid was degraded to smaller molecules that could be metabolized by microbes. Anecdotal
521
information was presented that soil ozonation might “improve crop vigor, reduce insect and disease, enhance water
522
penetration, and reduce fertilizer needs.”
523
524
Raub et al. (2001) felt, however, that longterm studies were needed to see if oxidation of organic matter on the soil
525
surface would lead to surface crusting and loss of soil structure.
526
527
(3) Do you have any additional evidence on impact of ozone on the soil ecosystem, short or long term?
528
See Larson (1999), Lin and Klarup (2001), Hayes (2000) and Pryor (2001b).
529
530
(4) Have you seen any information on the effect of ozone application on soil organic matter and nutrient availability?
531
Ohlenbusch et al. (1998), Raub et al. (2001) and Lin and Klarup (2001) show humic acid breakdown into smaller
532
molecules. Pryor (2001b) showed improved soil colonization of Trichoderma after soil ozonation. This fact could
533
indicate that ozone treatment made more nutrients available. Earlier reports (Larson 1999) also speculated that the
534
ozone soil treatment increased nutrients available for crops.
535
536
(5) Please express your technical review, advice and conclusions distinctly on each of these uses of ozone. Is it possible to permit use for some
537
purposes but not others? (e.g for weed control but not soil pathogens)
538
1. Use of ozone to clean irrigation lines.
539
Cleaning irrigation lines with ozone seems a reasonable use of the material. Ozone is already being used to treat
540
irrigation water. It does not seem to be much of a jump to use it to clean the irrigation system.
541
542
However, if it is injected directly into the tubing and flushed with water, care must be taken to do it safely and
543
effectively.
544
545
2. Use of ozone to control soil pathogens.
546
Using ozone in this manner is probably safe enough, and data presented by Pryor (2001a) shows that there will
547
probably be few impacts on soil microflora.
548
However, I could not find any information on effects on earthworms.
549
550
My major concern is that the technology has not yet been optimized and may be somewhat unreliable. The problem
551
for pathogen control is soil penetration. Best results have come in sandy soils that were irrigated with water before
552
fumigation. Perhaps because of patchy field coverage, published field trials on ozone pathogen control give
553
inconsistent results. When yield increases do occur, they are not directly related to the dose of ozone used. Larger
554
application rates often give lower yields. It may be that any yield increases are due to improved nutrient availability
555
and better biocontrol. Both of these factors could vary considerably.
556
557
In the 1997 field trials reported at a methyl bromide alternatives conference, ozone was applied through drip tubing
558
buried about 3 inches deep to sandy pre-irrigated soil. This placed the ozone very near the root zones. With these
559
best-case conditions there were significant yield increases with tomatoes, carrots and strawberries (Pryor 1999).
560
561
California 1998 field trials were published in Larsen (1999). Ozone soil treatment reported here gave increased yields
562
of tomatoes, carrots, strawberries and other crops. Applications were made through drip irrigation tubing to sandy
563
soils. Large emitters (4 gallons/hr) were used to get a large flow rate. Strawberry fields that were treated were under
564
heavy attack of Verticillium. Strawberry yields increased 51% as a result of ozone treatment. Ozone application rates
565
were 400 lb/acre.
566
567
Hayes (2000) treated strawberry fields with ozone plus the biocontrol organism Trichoderma. The combination
568
treatment generally gave increased yields over controls. However, increases were smaller compared to earlier trials
569
because standard 0.5 gallon/hr irrigation drip emitters were used. According to the author, higher ozone flow rates
570
with the larger 4.0 gallons/hour emitters give better results, especially if you are not dealing with sandy soil.
571
572
In field trials conducted in 2000, Pryor (2001b) tried treating tomatoes with ozone for nematode control and
573
strawberries with ozone for pathogen control. Tomatoes were treated with ozone alone, ozone +biocontrol
574
organisms, and standard nematicides (Telone). The highest application rate of ozone gave yields lower than the
575
controls. Modest application rates of ozone plus biocontrol microbials gave yields similar to the standard chemical
576
Telone. Best yields were shown with biocontrol microbials alone. Only Telone gave any nematode control, but yields
577
with Telone were lower than with microbials alone.
578
579

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Strawberries were treated with ozone alone, ozone plus microbials, and microbials alone. None of the treatments
580
significantly increased yields over controls. This report, though, was for a year when the pathogen challenge was low.
581
582
Combination of ozone plus Trichoderma did, however, lead to increased colonization rates of the microbial (Pryor
583
2001b).
584
585
Despite my concerns about reliability, the technology should be allowed. Perhaps continued use will lead to more
586
reliable treatments.
587
588
3. Use of ozone for weed control.
589
Laboratory data supplied by Pryor (2001a) show that ozone should only have minor non-target impacts on the soil
590
ecosystem. The field test by Pryor and Bayer (2001) seems to establish efficacy. If oxidation of soil organic matter
591
causes negative longterm impacts on soil structure (Raub et al. 2001), NOSB can suspend its use.
592
593
594
Reviewer 1 Conclusion
Summarize why it should be allowed or prohibited for use in organic systems.
595
a. Ozone should be allowed in organic agriculture for cleaning irrigation lines. Use in this manner should not violate
596
any of the Section 2119 Criteria. Excessive amounts should not be used so there is no appreciable off-gassing and air
597
contamination.
598
599
b. Ozone should be allowed in organic agriculture for weed treatments. Publications cited show that it is generally
600
effective for this purpose, and use in this manner should not violate any Section 2119 Criteria. If long term use leads
601
to problems with soil structure, the NOSB can determine that this use should be suspended.
602
603
c. Application for pathogen control should not violate Section 2119 Criteria. I have some reservations, however, that
604
the technique has not yet been optimized for reliable pathogen control in the field.
605
606
Reviewer 1 Recommendation Advised to the NOSB:
607
The substance is Synthetic
608
Though a case can be made for non-synthetic, since ozone is already classified synthetic in Section 205.605 of the
609
Final Rule, it should be classified as synthetic for the cases below.
610
611
For Crops, the substance should be
612
Added to the National List.
613
614
Suggested Annotation, including justification:
615
Ozone should be added to the National List for the following applications:
616
1. For cleaning irrigation lines
617
2. For weed control
618
3. For soilborne pathogen control
619
620
621
Reviewer 2
[Ph.D. exposure assessment-toxicology, M.S. chemistry. Certification review committee member, Eastern U.S.]
622
623
Comments on Database
624
The following information needs to be corrected or added to the database:
625
626
The photochemical production of ozone in the troposphere, and the difficulties associated with minimizing its impact
627
are not adequately represented in this document. Most ozone in the troposphere is anthropogenically-generated, and
628
is often above 0.80 ppm in prolonged afternoon and evening episodes (Lioy and Dyba, 1989). At this concentration,
629
decreased pulmonary function and athletic performance, increased airway reactivity and decreased (respiratory)
630
particle clearance were found in non-smoking adults (Hobbes and Mauderly, 1991). Significant reductions on
631
respiratory function are proportional to tropospheric ozone concentration, which is alarming, as a large segment of
632
the US population resides in locations where the National Ambient Air Quality Standards (NAAQS) are violated for
633
more than 100 days per year (McDonnell et al., 1993).
634
635
OFPA Criteria Evaluation
636
(1) The potential of such substances for detrimental chemical interactions with other materials used in organic farming systems;
637
I agree with the criteria evaluation
638
639

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(2) The toxicity and mode of action of the substance and of its breakdown products or any contaminants, and their persistence and areas of
640
concentration in the environment;
641
The criteria evaluation needs to be corrected or amended as follows:
642
643
I don’t follow the NTP table very easily, as I don’t use LC data alone.
644
645
Long-term exposure studies indicate that the primary target tissues are the nasal epithelium and the centrianinar
646
region of the lung ((Hobbes and Mauderly, 1991). In the lower regions of the lung, where lining fluid is thin, damage
647
to cells may be due directly to O
3
(Pryor, 1992). In higher regions, aldehydes and peroxides, which result from
648
reactions in the lipid bilayers of the mucous lining with O
3
, may be inciting damage (ibid., 1992). See the section on
649
human health (number 4) for additional human toxicity.
650
651
(3) the probability of environmental contamination during manufacture, use, misuse or disposal of such substance;
652
I agree with the criteria evaluation.
653
654
(4) the effect of the substance on human health;
655
The criteria evaluation needs to be corrected or amended as follows:
656
657
A correlation has been drawn between tropospheric summer ozone concentration and emergency room hospital visits
658
for asthma, in four different regions of the North American continent (Cody, 1992). Healthy individuals at risk
659
included those who exercise outdoors and who occupationally remain outdoors for much of the day, and also
660
children, particularly in summer, when temperatures are comfortable for outdoor activities and ozone levels are at
661
their highest. (See Database section for related comments.)
662
663
(5) the effects of the substance on biological and chemical interactions in the agroecosystem, including the physiological effects of the substance on
664
soil organisms (including the salt index and solubility of the soil), crops and livestock;
665
Here is additional supporting information or comments.
666
667
A three year study of Scots pine seedlings led to the conclusion that in a relatively O
3
tolerant species, the chronic
668
effects of O
3
exposure include growth reduction, increased needle abscission and changes in C allocation that are
669
influenced by plant N availability (Utriainen and Holopainen, 2001).
670
671
Response to ozone in ponderosa pine was greatest when there was low nutrients supplied (Andersen and Scagel,
672
1997). Significant effects on below-grown respiratory activity were apparent before any reduction of total plant
673
growth was found.
674
675
(6) the alternatives to using the substance in terms of practices or other available materials; and
676
I agree with the criteria evaluation
677
678
(7) its compatibility with a system of sustainable agriculture.
679
I agree with the criteria evaluation.
680
681
RESPONSE TO ADDITIONAL QUESTIONS
682
683
1. Have you seen or can you find any specific mention of use of ozone injected in drip irrigation systems as a cleaning agent?
684
No
685
3. Do you have any additional evidence on impact of ozone on the soil ecosystem, short or long term?
686
No.
687
4. Have you seen any information on the effect of ozone application on soil organic matter and nutrient availability ?
688
See Ohlenbusch et. al 1998… I was unable to get more than the citation of the following. Also, see criterion (5).
689
Anderson, C.P. Ozone stress and changes below-ground: linking root and soil processes. Phyton. 2000,40: 7-12.
690
691
5. See Conclusion.
692
693
Reviewer 2 Conclusion
Summarize why it should be allowed or prohibited for use in organic systems.
694
The use of ozone may be seriously detrimental to the health of humans who work with it, and those exposed
695
indirectly, downwind of exposure. The use of a known and problematic air pollutant would make its consideration as
696
a tool in organic farming questionable. One argument that is commonly submitted, utilizes that characteristic odor of
697
O
3
as an early detection signal for avoidance. However, rapid olfactory fatigue is being overlooked, as is the tendency
698
for workers to ignore minor, acute irritations, in order to achieve the work goal. Long-term and cumulative effects
699
can not be ignored.
700

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701
Additionally, the references provided and which I have obtained make little reference to long term effects of ozone in
702
the soil characteristics. The effects of altering the humic acid fraction and precipitating iron oxides are significant to
703
ban its use in soil applications, as an organic treatment. Damage to plants also is of concern, as even ozone-tolerant
704
species are affected by ozone exposure. Further, I encountered no references in peer-reviewed work to impacts to
705
beneficial soil organisms.
706
707
The use of ozone for (1) control of soil borne pathogens, (2) weed control, (3) to treat livestock waste for either
708
control of pathogens or (4) to ozonate for fertilizer, should not be allowed, as the ecological and human health impact
709
may be too high to warrant its use. Cleaning irrigation lines without recapture, should not be allowed for latter
710
reason. However, water purification of recycled nursery or hydroponic and aquaculture systems, using the stipulation
711
of off-gas recapture, may be reasonable, since other options for this goal often add unwanted by-products into the
712
water stream.
713
714
Reviewer 2 Recommendation Advised to the NOSB:
715
The substance is Synthetic
716
For Crops the substance should _Not Be Added to the National List.
717
718
719
Reviewer #3
[
Organic farmer, organic inspector, works with organic certifier. Western U.S.]
720
721
OFPA Criteria Evaluation
722
723
For OFPA Criteria 1-3, 5-6:
724
I agree with the criteria evaluation
725
726
(4) the effect of the substance on human health;
727
728
I agree with the harmful effects discussed in the criteria section
729
730
I believe amendments should be added which discuss the claimed positive effects on human health. These effects fall
731
roughly in three categories; water purification, use as a residential and office air cleanser, and use in alternative and
732
conventional medicine. …The health claims [made by manufacturers of ozone generating] residential air purification
733
systems are discounted, and [consumers are] warned against their use by the American Lung Association. (ALA, 2002)
734
[Alternative medical publications describe] the use of ozone therapy in some human diseases and in medical therapy.
735
(Bocci, 1996, Figueras undated; Bocci et al 1994)
736
737
RESPONSE TO ADDITIONAL QUESTIONS
738
739
1. Have you seen or can you find any specific mention of use of ozone injected in drip irrigation systems as a cleaning agent?
740
Internet search turned up very few references concerning use of ozone in drip lines (Hassan, undated; Von Broembson
741
2002; Del Ag.2002)
742
743
3. Do you have any additional evidence on impact of ozone on the soil ecosystem, short or long term?
744
4. Have you seen any information on the effect of ozone application on soil organic matter and nutrient availability?
745
3 and 4. Discussion in criteria evaluation is sufficient. Some minor additional discussion is included in attached references.
746
747
5. Please express your technical review, advice and conclusions distinctly on each of these uses of ozone. Is it possible to permit use for some purposes but
748
not others? (e.g. for weed control but not soil pathogens)
749
I think it is possible but difficult to separate soil application of ozone for weed control but not for soil pathogens
750
control. The primary difference is the pounds per acre used. Appropriate record keeping may be able to track this, but
751
since ozone is generated on site, tracking could be more difficult. Assuming honesty and integrity on the part of the
752
producer, I believe it is difficult to justify limiting the amount of ozone used for these primary reasons:
753
754
The primary detrimental effects are how much ozone escapes into the atmosphere and how deeply the soil is
755
sterilized. The atmospheric problem is dealt with by system design and monitoring. It is also in the producer’s best
756
interest to not waste the costly ozone. A poorly designed or maintained system for weed control could leak more than
757
a well designed and maintained system for destroying soil pathogens. If both systems are well designed, the pollution
758
of the atmosphere would be minimal. In practice, it is an identical technique and practice being used. The problem of
759
how deeply the soil is sterilized is reflected in two concerns. One concern is what residues or breakdown products are
760
left and the other concern is the effects on the soil microorganisms. Some data indicates that the breakdown products
761

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of ozone in the soil are beneficial to the microorganisms and subsequently to the crops. The concern of how quickly
762
microorganisms recolonize is dependent of the effects of the residues. Ozone itself does not have significant residues
763
and its breakdown products may actually encourage both the growth and diversity of microorganisms.
764
765
Ozone treatment for soil pathogens is a possible replacement for far more toxic materials (which, ironically deplete
766
atmospheric ozone) and its use should be encouraged from the environmental perspective. The environmental
767
perspective is an important element of the organic industry both in producer’s intention and in market expectations.
768
769
Ozone’s use in the soil is a technique as well as a material that affects both weeds and microorganisms at all levels of
770
use. If it is approved for weed control but not soil pathogen control, it will be hard to specify what level will be
771
allowed. In some regions for some weeds, the application rate needed to be effective may also be effective for
772
controlling some soil pathogens. On what basis should it be decided which weeds and pathogens are allowed to be
773
controlled by this technique (and which aren’t) since the technique is the same and the residues similar at all levels?
774
775
For these reasons, I think if Ozone is approved for weed control, it should also be allowed for soil treatment.
776
777
Reviewer 3 Conclusion
– Summarize why it should be allowed or prohibited for use in organic systems.
778
779
Ozone is a highly reactive oxidizer, that leaves little residue and fewer decomposition products than other oxidizers
780
such as chlorine. It requires a high energy input and specialized equipment to produce. It does not have a history of
781
being used in organic agriculture. No major certification agencies make reference to it nor is it mentioned in organic
782
production guides. Ozone’s use in conventional agriculture is relatively recent and still in research and development
783
stage, though some commercial scale farms have begun to use it. The decision to use ozone by conventional growers
784
is based on weighing these factors; the increased costs, increased efficacy and environmental regulations. Ozone is an
785
alternative to materials that have higher undesirable residuals such as chlorine or are being phased out such as methyl
786
bromide.
787
788
Being highly reactive, ozone exhibits many conflicting properties depending on the concentration and on which trace
789
materials are present. It is.a major pollutant with severe negative health effects. It is used both in alternative and
790
conventional medicine in therapy and also in large scale water purification systems designed for human consumption.
791
792
As a TAP reviewer with a farmer’s perspective, my approach is to look primarily at the material itself, what it would
793
replace and how it would be used in organic production. Since the material is not currently used in organic agriculture;
794
the questions that need to be answered are: why would it be needed? What organic production problems might it
795
solve? Are the effects of using the material compatible with organic agriculture’s goals? I will also address the
796
environmental effects of producing the material.
797
798
The environmental effects of producing ozone are primarily related to the energy required to produce it (85% of
799
which is lost as heat). The cost of equipment and the effort needed to maintain it limit ozone’s use to medium and
800
large scale operations. The high energy cost is a potential reason to not permit its use in organic agriculture due to
801
energy related pollution. On the other hand, if a more efficient method of ozone production were developed, this
802
objection would disappear. Therefore, the high use of energy is not sufficient reason to support its ban from organic
803
agriculture.
804
805
The more important question is on what basis should a new, synthetic material be introduced to organic agriculture.
806
The only reasons for inclusion I can support are:
807
808
1. If the material being introduced replaces materials that are less desirable to use because of environmental, safety,
809
residue or health considerations. In short, if the new material fits the idealized organic criteria more closely than
810
existing materials. This concept envisions an evolving organic production system that continually changes toward the
811
idealized criteria as both new materials and new knowledge become available. This is true for some uses of ozone.
812
813
2. The material fits the criteria for use in organic agriculture except for being synthetic AND is an effective solution
814
for an organic production problem or contributes to the expansion of organic production systems. This concept
815
allows the methods and techniques of organic production to evolve and handle new situations and reach further into
816
mainstream society.
817
818
In the current organic climate, concerns about contamination from use of manures and compost products are new
819
threats to organic agriculture. An effective sanitizer or disinfectant without residues may be needed to meet changing
820
USDA and HAACP regulations and still be acceptable to the organic market. Ozone has already been accepted in
821
organic food processing for direct contact with food. Current ozone technology may not be sufficient to meet crop
822

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NOSB TAP Review Compiled by OMRI
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August 14, 2002
Page 15 of 18
production problems, but if more efficient ozone production or techniques were developed, the material itself may be
823
able to provide a partial solution.
824
825
Reviewer 3 Recommendation Advised to the NOSB:
826
Ozone should be considered as a Synthetic allowed only with annotations
827
828
1. Restricted to use as weed and disease control with appropriate environmental controls and monitoring AND only
829
after other methods have been tried. This method must be considered as a last resort
830
831
Comment- There are many approved organic alternatives for weed and disease control in soils. These should be
832
tried first. The potential for ozone to develop into an alternative to extremely high polluting materials is
833
important to explore. If shown to be effective and clean, it should be allowed as a tool for organic farmers.
834
835
2. Allowed for use in cleaning drip irrigation lines with appropriate environmental controls and monitoring
836
Comments- The efficacy of using ozone in this manner has not been shown but there is potential that it may be
837
an alternative to chlorine or hydrogen peroxide.
838
839
840
Conclusion - Ozone for organic crop production:
841
Two out of three reviewers felt that ozone should be permitted for use in organic crop production, with use limited to:
842
1) cleaning irrigation lines,
843
2) weed control and
844
3) for soilborne pathogen control.
845
846
One suggested further restrictions limiting weed and pathogen control use to that of “last resort. ” If approved for use,
847
this requirement is already established under 7CFR 205.206(d-e). A possible further restriction on use in irrigation as
848
suggested by one reviewer, could be stated at 205.601(a)(5) “ozone, injected in irrigation lines in a method to prevent off-
849
gassing.”
850
851
These two reviewers did not find a compelling reason to reject usage, despite a lack of data in some areas such as effect on
852
soil structure or earthworm populations. They did find some benefits to use and generally felt further experimentation
853
might yield more data on effectiveness and impact.
854
855
The third reviewer found that health and safety reasons are a strong argument to prohibit use, along with the known
856
effects on soil humic acid fraction, and the unknown long-term effects on soil and beneficial soil organisms.
857
858
This use is not permitted under current regulatory language of CODEX, the EU, or Japan and may require further
859
consultation over equivalency issues if approved in the US.
860
861
862
References
863
*= included in packet
864
865
*ALA 2002. Ozone Generators- What is Ozone Air Pollution? American Lung Association of Washington.
866
http://www.alaw.org/air_quality/information_and_referral/indoor_air_quality/ozone_generatiors.html
867
868
* Anderson, C.P. and C.F. Scagel, 1997. Nutrient availability alters belowground respiration of ozone-exposed ponderosa
869
pine.Tree Physiology, 1997, 17: 377-387. (abstract)
870
871
* Bao J., D. Fravel, G. Lazarovits, D. Chellemi, P. van Berkum, and N. O'Neill. 2000 Population Structure Of Fusarium
872
Oxysporum In Conventional And Organic Tomato Production In Florida. In: 2000 Annual International Conference on
873
Methyl Bromide Alternatives and Emissions Reductions, US EPA and USDA
874
http://www.epa.gov/ozone/mbr/airc/2000/7fravel.pdf
875
876
*Barth, G. 1995. The potential for slow sand filtration for recirculating hydroponic systems in Australia. South Australian
877
Research and Development Institute. Http://www.sardi.sa.gov.au/hort/floricul/barth3.htm.
878
879
*Blum, U., and D. Tingey. 1977. A study of the potential ways in which ozone could reduce root growth and nodulation
880
of soybean. Atmospheric Environment. 11:737-739.
881
882

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Crops
August 14, 2002
Page 16 of 18
* Bocci, V., F. Corradeschi, Silva Silvestri, E. Luzzi and L. Paulesu. 1994. Further Evaluation of the Therapeutic Index of
883
Ozone Used in Autohemotherapy. From the Proceedings, Ozone Application in Medicine, September 1, 1994, Zurich Switzerland,
884
no organization named. Excerpted on internet at http://www.o3therapy.com/further.htm
885
886
* Bocci,V. 1996. Ozone as a bioregulator: Pharmacology and toxicology of ozone therapy today. Journal of Biological
887
Regulators and Homeostatic Agents Vol. 10 number 2 pg. 31-53 abstract available at http://www.o3therapy.com
888
889
* Bocci, V., C. Aldinucci, E. Borrelli, F. Corradeschi, A. Diadori, G. Fanetti and F. Valacchi. 2001. Ozone in medicine.
890
Ozone Science and Engineering 23:207-217.
891
892
*Boyette, C.D., Abbas, H.K., and H.L. Walker. 1999. Bioherbicides as alternatives to methyl bromide foe weed control in
893
tomato. In: Annual International Conference on Methyl Bromide Alternatives and Emissions Reductions. US EPA and USDA.
894
895
Brady, N.C. 1974. Ed. 8
th
Edition. The Nature and Properties of Soils. McMillan Pub. Co. NY pp .639.
896
897
Braghetta A., J Jacangelo, R Rhodes Trussell, J Meheus, M. Watson. 1997 The practice of chlorination: application,
898
efficacy, problems and alternatives. Internationl Water Supply Association Blue Pages.
899
http://www.iwahq.org.uk/pdf/bp0004.pdf
900
901
*Budavari, S. 1996. The Merck Index 12
th
Ed. Whitehouse Station NJ, Merck and Co.
902
903
* Bull, C. T. , K. G. Shetty, and K. V. Subbarao . 2000 . Interactions Between Myxobacteria, Plant Pathogenic Fungi and
904
Biocontrol Agents In: 2000 Annual International Conference on Methyl Bromide Alternatives and Emissions Reductions. US EPA
905
and USDA http://www.epa.gov/ozone/mbr/airc/2000/94bull.pdf
906
907
*Chase, C.A., Sinclair, T., Chellemi, D., Olson, S., Gilreath, J. and S. Locascio. 1999. Heat-retentive films for increasing
908
soil temperatures during solarization in a humid, cloudy environment. Hortscience 34(6):1085-1089.
909
910
*Chase, C.A., Sinclair, T. and S. Locasio. 1999. Effects of soil temperature and tuber depth on Cyperus spp. Control.
911
Weed Sci. 47:467-472.
912
913
*Chellemi, D., Olson, S., Mitchell, D., Secker, I., And R. McSorley. 1997. Adaptation of soil solarization to the integrated
914
pest management of soilborne pests of tomato under humid conditions. Phytopathology. 87(3)250-258.
915
916
Cody, R.P. 1992, Environmental Research, 58:184-194.
917
918
* Del Agricultural. 2000 Complete Understanding of Ozone Use and Technology
919
http://www.delozone.com/Pages/agozonefacts.html
920
921
* Duniway, J. M., J. J. Haoa, D. M. Dopkinsa, H. Ajwab, and G. T. Brownec. 2000. Some Chemical, Cultural, And
922
Biological Alternatives To Methyl Bromide Fumigation Of Soil For Strawberry. In: 2000 Annual International Conference on
923
Methyl Bromide Alternatives and Emissions Reductions. US EPA and USDA.
924
http://www.epa.gov/ozone/mbr/airc/2000/9duniway.pdf
925
926
Engelhard, A.W. 1989. Ed. Soilborne Plant Pathogens: Management of Diseases with Macro and Microelements. APS Press, St. Paul
927
Minn. Pp. 217.
928
929
* Figueras MD José Turrent, . Antonio A. Ramírez de Arellano Llovet MD. (no date) Ozone vs. Ozone Therapy: The
930
Paradox” Ozone Research Center, Havana Cuba. http://www.o3therapy.com/PARADOX.htm
931
932
* Francis, A. W. 1997. Ozone. In McGraw-Hill Encylclopedia of Science and Technology 8
th
Ed. v. 12: 683-686. McGraw-Hill,
933
NY.
934
935
*Gilreath, J., Noling, J., Locascio, S. and D. Chellemi. 1999. Efficacy of methyl bromide alternative in tomato and double
936
cropped cucumber. In: Annual International Conference on Methyl Bromide Alternatives and Emissions Reductions. US EPA and
937
USDA.
938
*Giraud, D.D., Westerdahl, B., Riddle, L., Anderson, C., and A. Pryor. 2001. Hot water and ozone treatments of Easter
939
lily for the management of lesion nematode, Pratylenchus penetrans. Phytopathology. 91(6 supplement) S134.
940
941

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Crops
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* Hassan, F. H. (undated) Cleaning of Drip Lines. The Microirrigation Forum. Downloaded Aug. 2002 from
942
http://www.microirrigationforum.com/new/archives/cleandlines.html
943
944
*Hatzios, K., amd Y. Yang. 1983. Ozone-herbicide interatctions on sorghum (Sorghum bicolor) and velvetleaf (Abutilon
945
theophrasti) seedlings. Weed Science 31:857-861.
946
947
* Hayes, C. 2000. Ozone biocidal properties and stimulation of Trichoderma harzianum (strain T-22) when applied in
948
combination as an environmentally benign alternative for methyl bromide. EPA Grant 68D99035, Bioworks Inc.
949
950
* Herman, M. Feb 13, 2002. electronic mail: Ozone as an antimicrobial agent, crop production aid. Sent to NOSB members
951
and NOP.
952
953
Hobbes C.H. and J.L. Mauderly. 1991, Clinical Toxicology, 29:375-384.
954
955
*Hoitink, H., and M. Krause. 1999. New approaches to control of plant pathogens in irrigation water. In: Ornamental
956
Plants – Annual Reports and Research Reviews 1999, special Circular 173-00. Ohio State University.
957
Http://ohioline.osu.edu/sc173/sc173_13.html.
958
959
*Kirk-Othmer 1996. Encylopedia of Chemical Technology, 4
th
Ed. Vol. 17. J. Kroschwitz, ed. pp 987-994. John Wiley, NY. Price
960
961
* Larson, L.E. 1999. Integrated Agricultural Technologies Demonstrations. Public Interest Energy Research (PIER) Rpt. No.
962
P600-00-012, California Energy Commission, Sacramento, CA. 100 pp.
963
964
* Liberti, L. and M. Notarnicola. 1999. Advanced treatment and disinfection for municipal wastewater reuse in agriculture.
965
Water Sci. Tech. 40(4-5):235-245.
966
967
* Liew, Chiam L.; R. Prange. 1994. Effect of ozone and storage temperature on postharvest diseases and physiology of
968
carrots (Daucus carota L.). J. Amer. Soc. Hort. Sci. 119(3):563-567.
969
970
* Lin, M. and D.G. Klarup. 2001. The effect of ozonation of humic acids on the removal efficiency of humic acid-copper
971
complexes via filtration. Ozone Science and Engineering 23:41-51.
972
973
Lioy, P. and Dyba, R. 1989. Toxicology and Industrial Health, 5:493-504.
974
975
Klaasen, C.D. 2001. Casarett & Doull’s Toxicology (6
th
ed.) New York: McGraw-Hill.
976
977
*Locascio, S., Olson, S., Chase, C.A., Sinclair, T., Dickson, D. Mitchell, D. and D. Chellemi. 1999. Strawberry
978
production with alternatives to methyl bromide fumigation. In: Annual International Conference on Methyl Bromide Alternatives
979
and Emissions Reductions. US EPA and USDA.
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981
*Mathers, H. 2000. Weed Control: Root rots, recirculated water and disinfectants. Part 2. Ohio State University.
982
Http://hcs.osu.edu/basicgreen/diseases/rootrot2.htm.
983
984
McDonnell, W.F., Zenick, H. and C. Hayes 1993.J. Air Waste Man. Assoc., 43:950-954.
985
986
*Mersie, W., T. Mebrahtu, and M. Rangappa. 1990. Response of corn to combinations of atrazine, propyl gallate and
987
ozone. Environmental and Experimental Botany. 30(4):443-449.
988
989
* NIDO 1997 National NIDO Project. Water disinfestation:- Chloro-bromination and ozone systems get the thumbs up!
990
Nursery Paper No. 8-97. Http://www.ngia.com.au/np/np97_8.html.
991
992
*Ohlenbusch, G., Hesse, S., and F. H. Frimmel. 1998. Effects of ozone treatment on the soil organic matter on
993
contaminated sites. Chemoshpere vol. 37 (8):1557-1569.
994
995
*Ozonators. Http://www.greenair.com/ozonat.htm.
996
997
Pryor, W.A. 1992. Free Radical Biology and Medicine, 12:83-8.
998
999
*Pryor, A. 1996. Method and apparatus for ozone treatment of soil to kill living organisms. US Patent #5,566,627.
1000
1001
_______ 1997. Method and apparatus for ozone treatment of soil. US Patent #5,624,635.
1002

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Crops
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1003
*_______.1999. Results of 2 years of field trials using ozone gas as a soil treatment. In: 1999 Annual International Conference
1004
on Methyl Bromide Alternatives and Emissions Reductions, G. L. Obenauf, ed. US EPA and USDA.
1005
*_______.2001. Petition For the Inclusion of Ozone Gas Used for Weed Control in the National List. Submitted to
1006
National Organic Program, USDA.
1007
1008
* Pryor, A. 2001b. Field trials for the combined use of ozone gas and beneficial microorganisms as a preplant soil
1009
treatment for tomatoes and strawberries. Pest Management Grants Final Report. Contract No. 99-0220 California Dept.
1010
Pesticide Regulation. 18 pp.
1011
1012
Quarles, W. and S. Daar. 1996. IPM Alternatives to Methyl Bromide. Bio-Integral Resource Center, Berkeley, CA 94707.60 pp.
1013
1014
*Qui, J.J., Westerdahl, B., Pryor, A., and C.E. Anderson. 2001. Reduction of root-knot nematode, M. javanica, in soil
1015
treated with ozone. (abstr.) Phytopathology 91(6 supplement) S141.
1016
1017
* Raub, L., Amrhein, C., and M. Matsumoto. 2001. The effects of ozonated irrigation water on soil physical and chemical
1018
properties. Ozone Science and Engineering. 23(1):65-76.
1019
1020
* Richardson, M. L. 1994. The Dictionary of Substances and their Effects. P 388-391. Royal Soc. Chemistry, Cambridge UK
1021
1022
*Sances, F., and E. Ingham. 1999. Conventional and organic alternatives to methyl bromide on California strawberries. In:
1023
Annual International Conference on Methyl Bromide Alternatives and Emissions Reductions. US EPA and USDA.
1024
1025
* Sances F. 2000. Conventional and organic alternatives to methyl bromide on California strawberries. In : 2000 Annual
1026
International Conference on Methyl Bromide Alternatives and Emissions Reductions. US EPA and USDA.
1027
http://www.epa.gov/ozone/mbr/airc/2000/24sances.pdf
1028
1029
*Sandermann, H. 1996. Ozone and Plant Health. Annual Review of Phytopathology. 1996. 34:347-366.
1030
1031
*Smith, R., Lanini, W.T., Gaskell, M., Mitchell, J., Koike, S. and C. Fouche. 2000. Weed management for organic crops.
1032
Univ. of California, Div. Agriculture and Natural Resources, Publication 7250.
1033
1034
*Unal, R., Kim, J., and A. Yousef. 2001. Inactivation of Escherichia coli O157:H7, Listeria monocytogenes, and
1035
Lactobacillus leichmannii by combination of ozone and pulsed electrical field. J. of Food Protection. 64(6):777-782.
1036
1037
* US EPA 1996. Methyl Bromide Alternatives Case Studies Vol. II. Organic Strawberry Production As An Alternative to
1038
Methyl Bromide http://www.epa.gov/ozone/mbr/casestudies/volume2/orgsber2.html
1039
1040
US EPA 1997. Methyl Bromide Alternatives Case Studies Vol. III. Disease Suppressive Compost as an Alternative to
1041
Methyl Bromide. http://www.epa.gov/ozone/mbr/casestudies/volume3/compost3.html
1042
1043
* United States EnvironmentalProtection Agency, 1999. Alternative Disinfectants and Oxidents Guidance Manual. Office of
1044
Water. EPA 815-R-99-014, April 1999. http://www.epa.gov/safewater/mdbp/alternative_disinfectants_guidance.pdf
1045
1046
US EPA 2000. Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions
1047
http://www.epa.gov/ozone/mbr/airc/2000/index.html
1048
1049
* Utriainen, J. and T. Holopainen. 2001. Nitrogen Availability modifies the ozone responses of Scots pine seedlings
1050
exposed inan ope-filed system. Tree Physiology. 21:1205-13.
1051
1052
*Von Broembsen, S. 2002. Disease management and water recycling. Oklahoma Cooperative Extension Service.
1053
http://zoospore.okstate.edu/nursery/managing/disease/index.html and
1054
http://zoospore.okstate.edu/nursery/managing/treat/ozonation.html
1055
1056
*von Broembsen, S. Capturing and recycling irrigation water to protect water supplies. In: E-951, Water Quality Handbook
1057
for Nurseries. Oklahoma Extension Service. Http://okstate.edu/OSU_Ag/agedcm4h/pearl/e951/e951ch7.htm.
1058
1059
*Wohanka, W. 1995. Disinfection of recirculating nutrient solutions by slow sand filtration. Acta Horticulturae 382:246-
1060
251.
1061
1062
This TAP review was completed pursuant to United States Department of Agriculture Purchase Order # 43-6395-2900A.
1063