National Organic Standards Board

Livestock Subcommittee

Petitioned Material Proposal

Aluminum Sulfate

June 21, 2016

Summary of Petition:

In August 2013 the NOP received a petition to add Aluminum Sulfate to the National List of synthetic 

substances allowed for use in organic livestock production 7 CFR 205.603 as a poultry litter treatment.

Summary of Review:

Manufacture and Uses of the Substance:

The intended and current use of aluminum sulfate is to be used as a poultry and livestock bedding 

amendment. Aluminum sulfate has been used in poultry, turkeys and livestock production for decades 

to safely and effectively protect animals and caretakers from volatilized ammonia that is generated from 

poultry and livestock manure, which accumulates in poultry and livestock bedding. For the sake of 

clarification, the term litter will be used synonymously with bedding and mixtures of used bedding and 

manure. Volatilized ammonia that occurs from the natural decomposition process in litter is the result of 

bacterial enzyme hydrolysis of uric acid to urea which is further hydrolyzed to ammonia (NH3). 

Ammonia has been shown to be detrimental to animal health, livability, well-being and overall live 

performance. Aluminum sulfate reacts with ammonia by donating acid ions, converting ammonia (NH3) 

to ammonium (NH4+), a highly reactive ion that bonds with nitrates, phosphates and sulfates forming 

stable non-volatile ammonium salts that are retained in the litter, which improve the litter’s nutrient 

value as a natural fertilizer. In addition to litter treatment in the poultry house, aluminum sulfate is 

being petitioned for use in organic crop production as a poultry litter additive. Litter treated with 

aluminum sulfate differs from non-treated litter, as it contains more total nitrogen and less soluble 

phosphorous, which increases the nitrogen fertilizer value and reduces phosphorous pollution of surface 

waters (Moore and Watkins 2012).

By retaining nitrogen in the litter through the conversion of NH3 to NH4+, and by binding soluble 

phosphorus, the fertilizer nutrient value of alum treated litter is improved. When land applied, litter that 

has been treated with alum contains bound soluble phosphorus that is utilized by plants on an as need 

basis. Plants have the ability to secrete acid from their roots to break the aluminum phosphate bonds 

re-solubilize phosphorus, making the essential nutrient available to plants. Aluminum sulfate in water 

treatment is classified as a flocculent and its function is to precipitate silica, minerals and organic 

material out of suspension. It is incorporated as one of the initial steps in municipal water purification. 

Aluminum sulfate based products have also been used for decades in municipal water treatment and 

lake restorations in the US and Canada. Over 50% of the municipal water in the US is treated with 

Chemtrade aluminum sulfate, the sponsor for this petition and aluminum sulfate is the most widely used 

water clarification chemical in the world. 

Dry aluminum sulfate is applied using drop spreaders, and centrifugal (slinger) spreaders, varying in size 

and complexity depending on application demand. Liquid aluminum sulfate is applied using a vehicle 

designed with a storage tanks, a pump and a PVC spray wand equipped with stainless steel nozzles. 

Typical dry product application rates range from 50 to 200 lbs/1000 ft2. Typical liquid product 

application rates range from 20 to 55 gal/1000 ft2. Dry aluminum sulfate is either applied by the poultry 
farmer or by custom applicators. Liquid aluminum sulfate and acidified aluminum sulfate products are 

applied by custom applicators. 

The manufacturing process for all the forms of aluminum sulfate included in the petition involves 

reacting liquid sulfuric acid with either bauxite ore containing aluminum hydroxide (Al(OH)3) and 

hydrated aluminum (Al2O3∙3H2O), or synthetic hydrated aluminum previously refined from bauxite. 

Bauxite ore is the main source of aluminum for the world and contains various aluminum minerals and 

two iron minerals (Amethyst Galleries 2014). The process creates hydrated aluminum sulfate per the 

following reactions: 

From bauxite: 3 H2SO4 + 2 Al(OH)3 + 12 H2O → Al2(SO4)3 • 18 H2O 52 

From hydrated aluminum: 3 H2SO4 +Al2O3∙3H2O + 12 H2O → Al2(SO4)3 ∙ 18 H2O 53 

The acidified formulation also contains synthetically produced sulfuric acid.

During the Spring 2016 in-person public comment session at the National Organic Standards Board 

meeting in Washington, DC, the board received one public comment that stated that there are OMRI 

listed poultry litter amendments currently in use. The Board was provided information from a 

manufacturer of a poultry litter amendment product, which is currently OMRI listed, that expressed

concerns they had with the TR. The commenter felt that the board should not approve synthetic poultry 

litter amendments when there are already effective OMRI listed products being used in the marketplace.

Category 1: Classification 

1. Substance is used for: Livestock 

 

2. For LIVESTOCK use:

a. Is the substance agricultural or non-agricultural? This substance is non-agricultural

b. If the substance is non-agricultural, is the substance: non-synthetic or synthetic. This 

substance is synthetic

The manufacturing process for all the forms of aluminum sulfate included in the petition 

involves reacting liquid sulfuric acid with either bauxite ore containing aluminum hydroxide 

(Al(OH) 3) and hydrated aluminum (Al2O3∙3H2O), or synthetic hydrated aluminum 

previously refined from bauxite. Bauxite ore is the main source of aluminum for the world 

and contains various aluminum minerals and two iron minerals (Amethyst Galleries 2014). 

The process creates hydrated aluminum sulfate per the following reactions:

From bauxite: 3 H2SO4 + 2 Al(OH)3 + 12 H2O → Al2(SO4)3 • 18 H2O 52 

From hydrated aluminum: 3 H2SO4 +Al2O3∙3H2O + 12 H2O → Al2(SO4)3 ∙ 18 H2O 53 

The acidified formulation also contains synthetically produced sulfuric acid.
3. For LIVESTOCK: This product would be listed at 205.603 Livestock Production-Synthetic. The 

substance contains sulfur. The substance is not an inert ingredient. Aluminum sulfate is not 

classified by the EPA as an inert of toxicological concern (it is on EPA List 4 (2004)). The 

substance is, however, approved as an adjuvant, used pre-harvest, and is exempted from the 

requirement of a tolerance (40 CFR 180.920). 

Category 2: Adverse Impacts 

1. What is the potential for the substance to have detrimental chemical interactions with other 

materials used in organic farming systems? [§6518(m)(1)]

TR LINES 435-478

Aluminum sulfate is being petitioned as an amendment to poultry litter for consideration in 

organic livestock application. Aluminum sulfate undergoes various chemical interactions with 

the poultry litter, altering several key chemical characteristics of the litter: 

1. The pH of the litter is reduced; however it is unlikely to fall below pH 7.0 in litter collected 

after the final grow out flock. Initially the treated litter pH does fall to about 5.7 and that pH is 

maintained for about 3-4 weeks (Moore et al. 2000) (Table 2). 

2. Aluminum sulfate reacts with water and naturally-occurring NH3 in the litter to form NH4+, 

thus stabilizing nitrogen and reducing NH3 gas volatilization to the atmosphere. In the soil 

environment, NH4+ is transient and is either rapidly taken up by plants, microbially transformed 

to NO32- which can be taken up by plants or lost to leaching, or anaerobically transformed by 

microorganisms to N2 and N2O which are lost to the atmosphere (Halvin et al. 2005). Although 

nitrogen is more persistent in the litter, there is no effect on cumulative soil nitrogen 

accumulation compared to non-treated litter, as aluminum sulfate does not alter the organic 

fraction of the total nitrogen. 

Poultry litter is a significant source of NH3 in the atmosphere, which causes formation of aerosol 

particles. It is also a source of nitric acid deposition to land or water bodies where it causes land 

and water acidification and nitrate pollution (NOAA 2000). Aluminum sulfate decreases 

atmospheric pollution of NH3 by reducing litter pH, which converts NH3 to water-soluble NH4+ 

(Shah et al. 2006). Incubation studies estimate approximately 14 g N / kg litter is lost from nontreated litter as NH3, while ammonia loss from litter treated with aluminum sulfate ranges 

between 0.7 to 4.07 g N / kg litter between the high and low application rates (Moore et al. 

2000. Assuming 40,000 lbs. of litter for a 16,000 square foot poultry house containing 20,000 

broilers (Moore and Watkins 2012), this represents a reduction of about 400 lbs. of NH3-N lost 

to the atmosphere over a 42-day period with low rates of aluminum sulfate, and about 560 lbs. 

of NH3-N at high rates of aluminum sulfate. 

3. Litter treated with aluminum sulfate contains less soluble phosphate (PO43-) than nontreated litter, as Al3+ reacts with PO43- to form insoluble AlPO4 (Table 2). Although the total 

phosphorous concentration in the litter does not change greatly, phosphorous becomes less 

plant-available, and likelihood of phosphorous transport to surface water is reduced. Aquatic 

ecosystems tend to be phosphorous-limited, and phosphorous eutrophication of natural water 
bodies is reduced when land-applied litter is treated with aluminum sulfate. The insoluble 

aluminum phosphate is not available to plants as nutrients and instead stays in the soil as a 

mineral (Moore and Edwards 2005). 

4. Litter treated with aluminum sulfate contains both higher total aluminum and higher soluble 

aluminum than non-treated litter (Table 2); however, runoff from fields where aluminum 

sulfate-treated litter is applied does not contain significantly higher levels of aluminum than 

fields where non-treated litter is applied (Moore et al. 1998). 

5. Litter treated with aluminum sulfate contains higher total sulfur and higher soluble sulfur 

than non-treated litter (Table 2). 

6. Concentration of soluble arsenic is reduced by aluminum sulfate treatment due to arsenic coprecipitation by aluminum (Violante et al. 2006) (Table 2). 

2. What is the toxicity and mode of action of the substance and of its breakdown products or any 

contaminants, and their persistence and areas of concentration in the environment? 

[§6518(m)(2)]

TR LINES 356-387

Toxicity: Aluminum sulfate is considered a dry acid, and is an irritant to the skin and eyes (UNLIO 2012). However, acidity created by the substance is neutralized by the litter, and litter 

applied to land generally has a near-neutral pH (Sims and Luka-McCafferty 2002). 

Mode of action: Aluminum sulfate reacts with water to create acid, which reduces ammonia 

losses from litter in confined poultry operations. Furthermore, aluminum causes precipitation of 

phosphates, reducing phosphorus solubility in the land-applied litter (Moore and Watkins 2012). 

Breakdown products: Breakdown products of aluminum sulfate include Al3+, Al(OH)2+, 

Al(OH)2+, Al(OH)3, SO42-, HSO4-, and H2SO4, and H3O+ (McBride 1996). Aluminum phosphate 

(Al(PO4)) precipitate is also formed via reaction of Al3+ with phosphates in the litter (Warren et 

al. 2008). 

Toxicity of breakdown products: Free Al3+ is a toxic species that increases in concentration as 

pH decreases, and typically reaches phytotoxic levels when pH falls below 5.0 (Havlin et al. 2005). 

Poultry litter without aluminum sulfate typically ranges in pH from 8.0 to 8.9 (Sims and LukaMcCafferty 2002). Shortly after aluminum sulfate application, pH of the litter decreases to about 

5.7, but becomes neutralized (near pH 7.0) after 3-4 weeks due to reaction with NH3 in the 

poultry guano (Moore et al. 2000). Thus, although adding aluminum sulfate increases total 

concentration of aluminum, persistence of the toxic Al3+ species is not enhanced. In contrast, 

application of litter near pH 7.0 to acidic soils decreases solubility of toxic Al3+ (Moore and 

Edwards 2005). 

Persistence of the breakdown products: Aluminum hydroxide and phosphates from aluminum 

sulfate addition to poultry litter are persistent in the soil after land application due to low 

solubility (Warren et al. 2008). Sulfates, however, are more soluble, serve as a source of sulfur 

for crop plants, or are lost to leaching (Havlin et al. 2005). 
Contaminants: The primary contaminants present in the Al2O3 precursor to aluminum sulfate 

include SiO2, Fe2O3, and Na2O, and could carry though into the final aluminum sulfate product, 

however do not pose toxicological concerns (Carter and Norton 2007) 

3. Describe the probability of environmental contamination during manufacture, use, misuse or 

disposal of such substance? [§6518(m)(3)]

TR LINES 392-429

Aluminum sulfate is a dry acid, and can create zones of high acidity if accidentally spilled. Acid 

damage severity from a concentrated spill is dependent on the quantity spilled, and also on the 

moisture available for reacting. If the spilled material does not come into contact with moisture, 

the majority of the material could be cleaned up before significant acidification occurs. . But, 

surfaces of most soils are typically fissured and loose, and sometimes moist, making complete 

soil cleanup unlikely. Aluminum sulfate is designated as a hazardous substance under the 

CERCLA (superfund), and discharges exceeding 5,000 lbs (2,270 kg) require notification to the 

U.S. Environmental Protection Agency (TABLE 302.4 40 CFR). 

Localized environmental acidification has a profound impact on chemical equilibrium regulating 

biological systems. In the soil, acidic conditions cause enhanced solubility of the Al3+ species, 

which is toxic to plant roots. Furthermore, both H+ and Al3+ are more strongly adsorbed to soil 

cation exchange sites than calcium, magnesium, and potassium and cause potential soil 

depletion of these nutrients via leaching. Soil remediation of large aluminum sulfate spills can be 

accomplished with a liming agent to neutralize the acidity and reduce solubility of Al3+ (NIH 

2014). 

Aluminum sulfate is sometimes deliberately added to water bodies impaired by phosphorus 

eutrophication, but accidental discharge of large quantities could cause excessive water 

acidification and subsequent solubilization of Al3+ which is toxic to aquatic organisms (UN-ILO 

2012). 

Personal protective equipment should be used when applying aluminum sulfate in the poultry 

house, but no specific precautions are needed for handling spent litter treated with aluminum 

sulfate due to the high level of dilution in the litter. In the poultry house, any aluminum sulfate 

spills should be incorporated into the litter to prevent ingestion by the birds (Walker and Burns 

2000). Applications of liquid ammonium sulfate are typically made by certified applicators due 

to transport restrictions (Moore and Watkins 2012). 

Aluminum sulfate reduces environmental contamination of phosphorus in natural water bodies 

from surface litter applications, compared to non-treated litter. Moore and Edwards (2005) 

measured 340% greater cumulative phosphorus load in runoff water from non-treated litter 

than from treated litter in a paired watershed study. 

The process of extracting bauxite ore has a deleterious impact on the environment through 

habitat degradation and fragmentation by roads, and through carbon emissions (Cooke 1999). 

After extraction, regulations in some countries require replacement of topsoil and other 
remediation measures; however quality of land after remediation is unlikely to be equivalent to 

before-extraction parameters (Cooke 1999). Most of the bauxite extraction worldwide is for the 

production of aluminum oxide, and less than 5% of bauxite imported into the U.S. is used for 

other purposes including aluminum sulfate production (USGS 2014) 

4. Discuss the effect of the substance on human health. [§6517 (c)(1)(A)(i); §6517 (c)(2)(A)(i); 

§6518(m)(4)].

TR LINES 544-563

Aluminum sulfate reacts with water to form sulfuric acid, which is an irritant. Aluminum sulfate 

is corrosive to the eyes; skin contact causes a rash and burning feeling, and inhalation causes 

throat and lung irritation (New Jersey Department of Health 2009). The magnitude of the toxic 

response to aluminum sulfate is completely dose-dependent, and the substance is permitted as 

a food additive in small quantities. Minor ingestion of dilute solutions causes stomach upset, 

while substantial ingestion can rarely cause hemorrhagic gastritis, circulatory collapse and multiorgan failure (United Kingdom National Poisons Information Service 1996). 

Aluminum is a subject of medical contention with suspected links to Alzheimer’s disease. 

Implications of a link between Alzheimer’s disease and aluminum have been made for 

approximately 40 years. The current large body of research has not concluded specific roles of 

aluminum in contributing to Alzheimer’s disease, but also has not dismissed aluminum as a noncontributor to the disease (Agency for Toxic Substances and Disease Registry 2008; Exeley 2001). 

Under FDA regulations, aluminum sulfate is generally recognized as safe (GRAS) as a food 

additive when used in accordance with good manufacturing or feeding practice (CFR 

182.1125(b)). 

Although aluminum sulfate has chronic toxicity for human exposure, use of the substance as 

petitioned should not have negative effects on human health. Use of the substance as 

petitioned decreases ammonia concentration in the atmosphere of poultry houses, which has a 

positive impact on both health of the birds and health of workers (Moore et al., 2000).

5. Discuss any effects the substance may have on biological and chemical interactions in the 

agroecosystem, including the physiological effects of the substance on soil organisms 

(including the salt index and solubility of the soil), crops and livestock. [§6518(m)(5)] 

TR LINES 485-522

Aluminum sulfate is not applied while birds are in the poultry house. The substance is not 

applied before the first flock grow-out; however, it is systematically applied thereafter before 

every flock is exposed to the litter. Any spills or concentrations of the product should be 

dispersed into the litter to avoid consumption by young chicks (Walker and Burns 2000). As 

stated in the petition, aluminum sulfate is not applied to feed. In the event of accidental 

ingestion, aluminum sulfate is corrosive and irrigating to the digestive system and kidneys of 

birds (Dumonceaux and Harrison 2013). In one study, Japanese quail fed aluminum sulfate as 

>0.10% of their diet reduced body weight accumulation, eggshell strength, plasma inorganic 
phosphorous, feed consumption, and egg production (Hussein et al. 1988). Physiological effects 

of aluminum sulfate intake by broiler chickens occurs at higher intake levels than quail, with 

decreases in weight gain when consumed at >0.93% of the diet. Higher concentrations of 

aluminum sulfate in the diet cause more severe depressions in weight gain, decreased bone 

strength, and serum phosphorous. At application rates of 100 g / kg litter, birds would need to 

ingest 10% of total dietary intake as litter to exceed 0.93% aluminum sulfate in the diet, and the 

aluminum would need to be in the original non-reacted aluminum sulfate crystalline form which 

does not persist in the presence of moisture. Typical observed litter ingestion rates are below 

this threshold, ranging from 2% to 5% of daily dietary intake. Aluminum sulfate is toxic to 

poultry if directly ingested in large quantities, but not at levels expected from litter consumption 

(Huff et al. 1996). When aluminum sulfate is used, mortality decreases and poultry weight gain 

increases, indicating the birds are likely not suffering toxic effects from incidental aluminum 

sulfate ingestion from the litter (Walker and Burns 2000). 

Deleterious effects of aluminum sulfate on the head, skin, feathers, or feet of poultry were not 

revealed in the literature review, but the material is an irritant (UN-LIO 2012). If aluminum 

sulfate remains in its original non-reacted dry form, there is potential for foot irritation. 

Producers can mitigate the potential of bird exposure by rototilling aluminum sulfate into the 

litter after application, and before birds are placed back in the poultry house. Liquid 

formulations are less likely to expose birds to concentrations of the chemical due to greater 

dispersal in the litter compared to dry formulations (Moore and Watkins 2012). Aluminum 

sulfate tends to dry out the litter, and in turkeys the use of aluminum sulfate decreased the 

incidence of foot pad dermatitis, which is associated with wet litter (Wu and Hocking 2011). 

In addition to the phosphorous-fixing properties of aluminum sulfate, litter treated with 

aluminum sulfate inhibits microbial phosphorous mineralization from organic matter (Warren et 

al. 2008). Although the literature review did not reveal problems associated with salinity of litter 

treated with aluminum sulfate, treated litter contains higher levels of soluble NH4+, and sulfur; 

thus, the salinity is likely higher than non-treated litter. However, salt damage to crops at 

normal agronomic application rates is likely low due to dilution factors (Sims and LukaMcCafferty 2002). Effects on bird health are positive, as ammonia accumulation causes lung 

irrigation to poultry (Walker and Burns 2000). Pathogen loads in the broiler house are reduced 

with aluminum sulfate, which combined with lower ammonia concentration in the air causes 

increased bird weight gain (Shah et al. 2006).

6. Are there any adverse impacts on biodiversity? (§205.200)

Aluminum sulfate reacts with water and naturally-occurring NH3 in the litter to form NH4+, thus 

stabilizing nitrogen and reducing NH3 gas volatilization to the atmosphere. In the soil 

environment, NH4+ is transient and is either rapidly taken up by plants, microbially transformed 

to NO32- which can be taken up by plants or lost to leaching, or anaerobically transformed by 

microorganisms to N2 and N2O which are lost to the atmosphere (Halvin et al. 2005). Although 

nitrogen is more persistent in the litter, there is no effect on cumulative soil nitrogen 

accumulation compared to non-treated litter, as aluminum sulfate does not alter the organic 

fraction of the total nitrogen.

Litter treated with aluminum sulfate contains less soluble phosphate (PO43-) than non-treated 

litter, as Al3+ reacts with PO43- to form insoluble AlPO4 (Table 2). Although the total 
phosphorous concentration in the litter does not change greatly, phosphorous becomes less 

plant-available, and likelihood of phosphorous transport to surface water is reduced. Aquatic 

ecosystems tend to be phosphorous-limited, and phosphorous eutrophication of natural water 

bodies is reduced when land-applied litter is treated with aluminum sulfate. The insoluble 

aluminum phosphate is not available to plants as nutrients and instead stays in the soil as a 

mineral (Moore and Edwards 2005). 

Litter treated with aluminum sulfate contains both higher total aluminum and higher soluble 

aluminum than non-treated litter (Table 2); however, runoff from fields where aluminum 

sulfate-treated litter is applied does not contain significantly higher levels of aluminum than 

fields where non-treated litter is applied (Moore et al. 1998). 

Litter treated with aluminum sulfate contains higher total sulfur and higher soluble sulfur than 

non-treated litter

Category 3: Alternatives/Compatibility

1. Are there alternatives to using the substance? Evaluate alternative practices as well as nonsynthetic and synthetic available materials. [§6518(m)(6)]

Alternatives to litter amendments include management practices such as proper air exchange in 

barns, removing caked areas and keeping litter areas dry.

TR LINES 569-581

Clinoptilolite is a naturally-occurring aluminosilicate zeolite which can absorb ammonia, 

reducing volatilization to the atmosphere. The literature contains results of mixed efficacy for 

this material, with some reports of decreased ammonia in broiler house air, and other reports of 

increased atmospheric ammonia (Amon et al. 1997; Karamanlis et al. 2008; Shah 2006). 

Agricultural lime can be applied to litter between flocks to increase litter pH, chemically inducing 

volatilization of large quantities of ammonia. The volatized ammonia can then be removed by 

ventilation before birds are placed back in the poultry house. Removal of ammonia from litter in 

between flocks reduces ammonia concentration in air for the subsequent grow-out, but does 

not mitigate ammonia production during the grow-out compared to acidification products. 

Although lime does not decrease total atmospheric ammonia pollution like aluminum sulfate, 

phosphorous in the litter is stabilized by complexation with calcium at high pH to reduce 

eutrophication of natural water bodies after land application of the litter (Shah 2006).

During the Spring 2016 in-person public comment session at the National Organic Standards 

Board meeting in Washington, DC, the board received one public comment that stated there are 

OMRI listed poultry litter amendments currently in use. The Board was provided information 

from a manufacturer of a poultry litter amendment product, which is currently OMRI listed, that 

expressed concerns they had with the TR. The commenter felt that the board should not 

approve synthetic poultry litter amendments when there are already OMRI certified listed being 

used in the marketplace. 
2. In balancing the responses to the criteria above, is the substance compatible with a system of 

sustainable agriculture? [§6518(m)(7)]

Yes, but it is unclear if this substance is needed in organic agriculture as alternatives exist. The 

subcommittee would like to pose the following questions:

1. Are there alternatives available to reduce Ammonia in poultry barns?

2. Do the alternatives work in the area of reducing or eliminating Salmonella that could be 

present in barns?

Classification Motion: Move to classify aluminum sulfate as petitioned as synthetic 

Motion by: Ashley Swaffar 

Seconded by: Harriet Behar

Yes: 7 No: 0 Abstain: 0 Absent: 1 Recuse: 0

Listing Motion: Motion to add aluminum sulfate as petitioned at §205.603

Motion by: Ashley Swaffar 

Seconded by: Jean Richardson

Yes: 0 No: 7 Abstain: 0 Absent: 1 Recuse: 0