using zeolites in agriculture

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Chapter VIII Using Zeolites in Agriculture Frederick A. Mumpton Department of the Earth Sciences State University College Brockport, NY 14420

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Page 1: Using Zeolites in Agriculture

Chapter VIII

Using Zeolites in Agriculture

Frederick A. MumptonDepartment of the Earth Sciences

State University CollegeBrockport, NY 14420

Page 2: Using Zeolites in Agriculture

ContentsP a g e

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 127Natural Zeolites . . . . . . . . . . . . . . . . . . . . . . . . 127Chemistry and Crystal Structure of

Zeolites . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128Properties of Zeolites. . . . . . . . . . . . . . . . . . 129

Applications in Agronomy ......,,.,.. . . . 133Fertilizer and Soil Amendments . . . . . . . . 133Pesticides, Fungicides, Herbicides. ,,.... 135Heavy Metal Traps . . . . . . . . . . . . . . . . . . . 135

Applications in Animal Husbandry . . . . . . . 136Animal Nutrition . . . . . . . . . . . . . . . . . . . . . 136Poultry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136Swine . . . . . . . . . . . . . . . . . . . . . . .+....... 136Ruminants . . . . . . . . . . . . . . . . . . . . . . . . . . . 139Excrement Treatment . . . . . . . . . . . . . . . . . 141Malodor and Moisture Control . . . . . . . . . 141Methane Purification. . . . . . . . . . . . . . . . . . 142

Aquacultural Applications . . . . . . . . . . . . . . . 143Nitrogen Removal From Closed or

Recirculation Systems . . . . . . . . . . . . . . . 143Aeration Oxygen Production . . . . . . . . . . . 144Fish Nutrition . . . . . . . . . . . . . . . . . . . . . . . . 144

Occurrence and Availability of NaturalZeolites .....,...,,.. . . . . . . . . . . . . . . . 144

Geological Occurrence. . . . . . . . . . . . . . . . . 144Geographic Distribution . . . . . . . . . . . . . . . 146Mining and Milling . . . . . . . . . . . . . . . . . . . 149

Discussion, ..,,.... . . . . . . . . . . . . . . . . . . . . 150Agronomic Applications . . . . . . . . . . . . . . . 150Animal Nutrition Applications ., ..,.,.., 151Excrement Treatment Applications . . . . . . 152

Conclusions and Recommendations . . . . . . . 152References .,.. . . . . . . . .,..,..+, . . . . . . . 155

Tables

Table No. Pagel. Representative Formulae and Selected

Physical Properties of ImportantZeolites . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

2. Growth Response of Radishes toAmmonium-Exchange Clinoptilolite . . . . 134

3, Growth Response of Radishes toNatural Clinoptilolite Plus Urea ,....., 134

4. Caloric Efficiencies of ZeoliteSupplements in Poultry Feeding . . . . . . . 136

5. Apparent Caloric Efficiency of Zeolitein Chicken Rations . . . . . . . . . . . . . . . . . . 137

6. Caloric Efficiency of ZeoliteSupplements in Swine Feeding . . . . . . . . 137

7. Effect of Zeolite Diets on Healthof Swine . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

8. Effect of Prenatal Zeolite Diet onNewborn Pigs, .,, . . ., ..,,.,.., ..,.,. 138

9. Effect of Zeolite Supplementing theDiets of Early Weaned Pigs . . . . . . . . . . . 139

10.

11.

12.

13.

14.

15.

16.17.

18.

19.

Effect of Zeolite Supplement inMolasses-Based Diets of Young Pigs .,. 139Effect of Clinoptilolite Supplementalin the Diet of Swine . . . . . . . . . . . . . . . . . 140Occurrence of Diarrhea and Soft-FecesAmong Calveson Diets SupplementedWith 5% Clinoptilolite . . . . . . . . . . . . . . . 141Effect of Zeolite Additions to ChickenDroppings . . . . . . . . . . . . . . . . . . . . . . . . . . 142Effect of Clinoptilolite Additions to theDiet of Trout . . . . . . . . . . . . . . . . . . . . . . . 144Reported Occurrences of SedimentaryZeolites . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148Countries Engaged in Zeolite Mining . . 150Organizations Engaged in Zeolite/Agronomic Investigations . . . . . . . . . . . . 151Organizations Engaged in AnimalNutrition Studies Using Zeolites . . . . . . . 152Zeolite Property Holders andZeoagricultural Research Efforts. ..,,,. 153

Figures

FigureNo. Pagel. Simple Polyhedron of Silicate and

. .

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.12.

Aluminate Tetrahedra . . . . . . . . . . . . . . . . 130Arrangements of Simple Polyhedra toEnclose Large Central Cavities .., ...,, 130Solid Sphere Models of SyntheticZeolite and Chabazite . . . . . . . . . . . . . . . . 131Stylized Illustration of the Entry ofStraight-Chain Hydrocarbons andBlockage of Branch-Chain Hydrocarbonsat Channel Apertures ,, ......,,,,,,., 131Langmuir-Type Isotherm for Adsorptionon Crystalline Zeolites IllustratingAlmost Complete Saturation at LowPartial Pressures of the Adsorbate ,,... 131Types of Ion-Exchange Isotherms for theReaction As + BZ = AZ + Bs, . . . . . . . . . 132Change of Soil Nitrogen of Paddy SoilWith Time . . . . . . . . . . . . . . . . . . . . . . . . . 133Yield of Chrysanthemums as a Functionof Potassium Level Supplied by One-TimeAdditions of Clinoptilolite . . . . . . . 134Cumulative Leachate NO3-N for BandedNH4-Exchanged Clinoptilolite andBanded Ammonium Sulfate ..,,,,,. . . . 135Methane-Purification System, PalesVerde Landfill . . . . . . . . . . . . . . . . . . . . . . 142Field Exposure of Zeolite Beds ,,, ,,,.. 145Scanning Electron Micrograph ofClinoptilolite Laths With Minor MordeniteFrom a Saline-Lake Deposit Tuff NearHector, CA . . . . . . . . . . . . . . . . . . . . . . . . . 146

Page 3: Using Zeolites in Agriculture

Chapter Vlll

Using Zeolites in Agriculture

AS agriculturalists the world over increasetheir effort to expand crop and animal produc-tion, more and more attention is being paid tovarious mineral materials as soil amendmentsand as dietary supplements in animal hus-bandry. The close relationship between theagricutura1 and geological sciences is notnew--crop production depends on the exist-ence and maintenance of fertile soil andagronomists rely on knowledge of mineralogyand geochemist}’ of clays and other soil con-stituents. In the animal sciences, the additionof crushed limestone to chicken feed tostrengthen egg shells is well known, as is theuse of bentonite as a binding agent in pelletizedanima1 feed stuffs.

Recently, one group of minerals has emergedas having considerable potential in a wide va-riety of agricultural processes. This group ofminerals is the zeolite group. The unique ion-exchange, dehydration-rehydration, and ad-sorption properties of zeolite materials prom-ise to contribute significantly to many years ofagricultural and aquacultural technology (60).

Most of the initial research on the use of zeo-lites in agriculture took place in the 1960s inJapan, Japanese farmers have used zeolite rockfor years to control the moisture content andmalodor of animal wastes and to increase thepH of acidic volcanic soils. The addition ofsmall amounts of the zeolites clinoptilolite andmordenite to the normal protein diet of pigs,chickens, and ruminants gave noticeable in-

Zeolites are crystalline, hydrated aluminosil-icates of alkali and earth metals that possessinfinite, three-dimensional crystal structures.They are further characterized by an ability tolose and gain water reversibly and to exchange

creases in the body weight and general “health”of the animals (52). The use of zeolites in ra-tions also appeared to reduce odor and asso-ciated pollution problems and to provide ameans of regulating the viscosity and nitrogenretentivity y of animal manure. These same zeo-lites were also found to increase the ammoni-um content of rice paddy soils when addedwith normal fertilizers.

Although most of these were preliminary re-sults and often published in rather obscurejournals or reports from local experiment sta-tions, they did suggest that zeolites could actas traps or reservoirs for nitrogen both in thebody and in the soil. The growing awarenessof such phenomena and of the availability ofinexpensive natural zeolites in the WesternUnited States and in geologically similar partsof the world has aroused considerable commer-cial interest. Zeolites are fast becoming the sub-ject of serious investigation in dozens of agri-cultural laboratories both here and abroad.Some of the ways in which zeolites can con-tribute to more efficient crop and livestock pro-duction are discussed below, along with theirrole in the rapidly expanding areas of fishbreeding and aquiculture. At this stage, thenumber of published papers dealing with “zeo-agriculture “ is quite small, and hard data arefew; however, the potential of these materialsin such areas is apparent, and zeolites showpromise of contributing directly to increasedagricultural productivity in the years to come.

ZEOLITES

some of their constituent elements without ma-jor change of structure. Zeolites were discov-ered in 1756 by Freiherr Axel Fredrick Cron-stedt, a Swedish mineralogist, who namedthem from the Greek words meaning “boiling

127

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stones, “ in allusion to their peculiar frothingcharacteristics when heated before the miner-alogist’s blowpipe. Since that time, nearly 50natural species of zeolites have been recog-nized, and more than 100 species having nonatural counterparts have been synthesized inthe laboratory. Synthetic zeolites are the main-stays of the multimillion-dollar molecular sievebusinesses that have been developed by UnionCarbide Corp., W. R. Grace& Co., Mobil Corp.,Norton Co., Exxon Corp., and several othercompanies in the last 25 years in the UnitedStates and by chemical firms in Germany,France, Great Britain, Belgium, Italy, Japan,and the Soviet Union.

Natural zeolites have long been known tomembers of the geological community as ubiq-uitous, but minor constituents in the vugs andcavities of basalt and other traprock forma-tions. It was not until the late 1950s that theworld became aware of zeolites as major con-stituents of numerous volcanic tuffs that hadbeen deposited in ancient saline lakes of theWestern United States or in thick marine tuffdeposits of Italy and Japan. Since that time,more than 2,000 separate occurrences of zeo-lites have been reported from similar sedimen-tary rocks of volcanic origin in more than 40 countries. The high purities and near-surfacelocation of the sedimentary deposits has

prompted intense commercial interest bothhere and abroad. Many industrial applicationsbased on the exciting bag of chemical and phys-ical tricks of zeolites have been developed.

The commercial use of natural zeolites is stillin its infancy, but more than 300,000 tons ofzeolite-rich tuff is mined each year in theUnited States, Japan, Bulgaria, Hungary, Italy,Yugoslavia, Korea, Mexico, Germany, and theSoviet Union. Natural zeolites have found ap-plications as fillers in the paper industry, aslightweight aggregate in construction, in poz-zolanic cements and concrete, as ion-exchang-ers in the purification of water and municipalsewage effluent, as traps for radioactive spe-cies in low-level wastewaters from nuclear fa-cilities, in the production of high purity oxy-gen from air, as reforming petroleum catalysts,as acid-resistant absorbents in the drying andpurification of natural gas, and in the removalof nitrogen compounds from the blood of kid-ney patients (58).

The applications and potential applicationsof both synthetic and natural zeolites depend,of course, on their fundamental physical andchemical properties. These properties are inturn related directly to the chemical composi-tion and crystal structure of individual species.

CHEMISTRY AND CRYSTAL STRUCTURE OF ZEOLITES

Along with quartz and feldspar, zeolites are tassium (K+) elsewhere in the structure. Thus,“tektosilicates, ” that is, they consist of three- the empirical formula of a zeolite is of the type:dimensional frameworks of silicon-oxygen( S i O4)

4 tetrahedral, wherein all four cornerM 2/ nO . Al2O a . xSiO2 ● y H2O

oxygen atoms of each tetrahedron are shared where M is any alkali or alkaline earth element,with adjacent tetrahedral. This arrangement of n is the valence charge on that element, x issilicate tetrahedral reduces the overall oxygen: a number from 2 to 10, and y is a number fromsilicon ratio to 2:1, and if each tetrahedron in 2 to 7. The empirical and unit-cell formulae ofthe framework contains silicon as its central clinoptilolite, the most common of the naturalatom, the structures are electrically neutral, as zeolites, is:is quartz (SiO2. In zeolite structures, however, (Na,K)2O . Al2O 3 ● 1 0 S i O2 ● 6 H2O orsome of the quadrivalent silicon is replaced bytrivalent aluminum, giving rise to a deficiencyof positive charge. This charge is balanced by Elements or cations within the first set of pa-the presence of mono- and divalent elements rentheses in the formula are known as ex-such as sodium (Na +), calcium (Ca2 + ), and po- changeable cations; those within the second set

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of parentheses are called structural cations, be-cause with oxygen they make up the tetrahe-dral framework of the structure. Loosely boundmolecular water is also present in the struc-tures of all natural zeolites, surrounding the ex-changeable cations in large pore spaces.

Whereas the framework structures of quartzand feldspar are dense and tightly packed,those of zeolite minerals are remarkably openand void volumes of dehydrated species asgreat as 50 percent are known (table 1). Eachzeolite species has its own unique crystal struc-ture and, hence, its own set of physical andchemical properties. Most structures, however,can be visualized as SiO4 and AlO4 tetrahedrallinked together in a simple geometrical form.This particular polyhedron is known as a trun-cated cube-octahedron. It is more easily seenby considering only lines joining the midpointsof each tetrahedron, as shown in figure 1.

Individual polyhedra may be connected inseveral ways; for example, by double four-ringsof oxygen atoms (figure 2a), or by double six-rings of oxygen atoms (figure 2b), the frame-work structures of synthetic zeolite A and themineral faujasite, respectively. Solid-spheremodels of synthetic zeolite A and of the mineralchabazite are illustrated in figures 3a, 3b.

once the water is removed from a zeolite,considerable void space is available withinboth the simple polyhedra building blocks andthe larger frameworks formed by several poly-hedra. Although water and other inorganic andorganic molecules would appear to be able tomove freely throughout a dehydrated zeoliteframework, the passageways leading into thesimple polyhedra are too small for all but thesmallest molecules to pass; however, ports orchannels up to 8 A in diameter lead into thelarge, three-dimensional cavities (figures 2a, 2b,3a, 3b).

Properties of Zeolites

Adsorption properties: Under normal condi-tions, the large cavities and entry channels ofzeolites are filled with water molecules form-ing hydration spheres around the exchange-able cations. Once the water is removed, usual-ly by heating to 3000 to 4000 C for a few hours,molecules having diameters small enough tofit through the entry channels are readily ad-sorbed on the inner surfaces of the vacant cen-tral cavities. Molecules too large to passthrough the entry channels are excluded, giv-ing rise to the well-known “molecular sieving”property of most crystalline zeolites (figure 4).

Table 1.— Representative Formulae and Selected Physical Properties of Important Zeolites

Void Channel Thermal Ion-exchangeZeolite Representative unit-cell formulaa volume a dimensions a stability capacity b

AnalcimeChabaziteClinoptiloliteErioniteFaujasiteFerrierite

Heulandite

LaumontiteMordenite

Phillipsite

Linde ALinde X

18%4739?3547

39

28

31

4750

2.6 A3.7 X 4.23.9 x 5.43.6 X 5.27.44.3 x 5.53.4 X 4.84.0 x 5.54.4 X 7.24.1 x 4.74.6 X 6 . 32.9 X 5.76.7 X 7 . 04.2 X 4 . 42.8 X 4.83.34.27.4

HighHighHighHighHighHigh

Low

LowHigh

Low

HighHigh

4.54 meq/g3.812.543.123.392.33

2.91

4.252.29

3.87

5.484,73

aTaken mainly from Breck, 1974, Meier and Olson, 1971 Void volume is determined from water contentbCalculated from unit-cell formula

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Figure 1. —Simple Polyhedron of Silicate and Aluminate Tetrahedra

a b

(a) Ball and peg model of truncated cube-octahedron. (b) Line drawing of truncated cube-octahedron,lines connect centers of tetrahedral

Figure 2.—Arrangements of Simple Polyhedra toEnclose-Large Central Cavities

a b

(a) Truncated cube-octahedra connected by double four-rings of oxy-gen in structure of synthetic zeolite A. (b) Truncated cube-octahedraconnected by double six-rings of oxygens in structure of faujasite.

The internal surface area available for adsorp-tion ranges up to several hundred square me-ters per gram, and some zeolites are capableof adsorbing up to about 30 weight percent ofa gas, based on the dry weight of the zeolite.

In addition to their ability to separate gasmolecules on the basis of size and shape, theunusual charge distribution within a dehy-drated void volume allows many species withpermanent dipole moments to be adsorbed

with a selectivity unlike that of almost all othersorbents. Thus, polar molecules such as water,sulfur dioxide, hydrogen sulfide, and carbondioxide are preferential] y adsorbed by certainzeolites over nonpolar molecules, such as meth-ane, and adsorption p recesses have been de-veloped using natural zeolites by which carbondioxide and other contaminants can be re-moved from impure natural gas or methanestreams, allowing the gas to be upgraded tohigh-Btu products. In addition, the small, butfinite, quadripole moment of nitrogen allowsit to be adsorbed selectively from air by a de-hydrated zeolite, producing oxygen-enrichedstreams at relatively low cost at room temper-ature. Both of the above processes may find ap-plication in agricultural technology.

Dehydration-rehydration properties: Becauseof the uniform nature of the pores of structuralcages, crystalline zeolites have fairly narrowpore-size distributions, in contrast to othercommercial absorbents, such as activated alu-mina, carbon, and silica gel. Adsorption on zeo-lites is therefore characterized by Langmuir-typeisotherms, as shown in figure 5. Here, percentof adsorption capacity is plotted against par-tial pressure of the adsorbate gas. Note that al-most all of the zeolite’s adsorption capacity for

Page 7: Using Zeolites in Agriculture

Figure 3.—Solid Sphere Models of Synthetic Zeolite and Chabazite

a b

(a) Solid-sphere model of the crystal structure of synthetic zeolite A (b) Solid-sphere model of the crystal structure of chabazite

Figure 4.—Stylized Illustration of the Entry of Straight.Chain Hydrocarbons and Blockage of Branch-Chain

Hydrocarbons at Channel Apertures

Figure 5.—Langmuir-Type Isotherm for Adsorption onCrystalline Zeolites Illustrating Almost Complete

Saturation at Low Partial Pressures of the Adsorbate

a particular gas (including water) is obtainedat very low partial pressures, meaning that al-though their total adsorption capacity may besomewhat less than those of other absorbents,(e.g., silica gel), zeolites are extremely efficientad sorbents even at low partial pressures. Thisproperty has been used in the zeolitic adsorp-tion of traces of water from Freon gas lines ofordinary refrigerators that might otherwisefreeze and clog pumps and valves. The extremenonlinearity of the water adsorption isothermsof zeolites has been exploited recently in thedeveloprnent of solar-energy refrigerators (81),

lon-exchange properties: The exchangeablecations of a zeolite are also only loosely bondedto the tetrahedral framework and can be re-moved or exchanged from the framework

structure easily by washing with a strong so-lution of another element. As such, crystallinezeolites are some of the most effective ion ex-changers known to man, with capacities of 3to 4 meq per gram being common. This com-

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pres with the 0.8 to 1.0 meq per gram cation-exchange capacity of bentonite, the only othersignificant ion-exchanger found in nature,

Cation-exchange capacity is basically a func-t ion of the degree of substitution of aluminumfor silicon in the zeolite framework: the greaterthe substitution, the greater the charge defi-ciency of the structure, and the greater thenumber of alkali or alkaline earth atoms re-quired for electrical neutrality. In practice,however, the cation-exchange capacity is de-pendent on a number of other factors as well,In certain species, cations can be trapped instructural positions that are relatively inacces-sible, thereby reducing the effective exchangecapacity of that species for that ion, Also, ca-tion sieving may take place if the size of theexchanging cat ion is too large to pass throughthe entry channels into the central cavities ofthe structure.

Unlike most noncrystalline ion exchangers,such as organic resins or inorganic alumino-silicate gels (mislabeled in the trade as “zeo-lites”), the framework of a crystalline zeolitedictates its selectivity toward competing ions.The hydration spheres of high-charge, small-size ions (e. g., sodium, calcium, magnesium)prevent their close approach in the cages to theseat of charge of the framework; therefore ionsof low charge and large size (e. g., lead, barium,potassium), that normally do not have hydra-tion spheres are more tightly held and selec-tively taken up from solution than are otherions, The small amount of aluminum in thecomposition of clinoptilolite, for example, re-sults in a relatively low cation-exchange capac-ity (about 2.3 meq/g); however, its cation selec-tivity is:

Cesium > Rubidium > Potassium > Ammonium >Barium > Strontium > Sodium

Calcium > Iron > Aluminum >Magnesium > Lithium (3).

Synthetic zeolite A, on the other hand, is moreselective for calcium than for sodium, and thus,acts as a water softener in laundry detergentswhere it picks up calcium from the wash waterand releases sodium (75).

Cation exchange between a zeolite (Z) anda solution (S) is usually shown by means of anexchange isotherm that plots the fraction of theexchanging ion (X) in the zeolite phase againstthat in the solution (figure 6). If a given cationshows no preference of either the solution orthe zeolite, the exchange isotherm would be thestraight line “a” at 450. If the zeolite is moder-ately or very selective for the cation in solution,curve b and c would result, respectively. If thezeolite is rejective of a particular cation, curved would result. Such is the selectivity of clin-optilolite for cesium or ammonium, for exam-ple. Clinoptilolite will take up these ions readilyfrom solutions even in the presence of highconcentrations of competing ions, a facilitythat was exploited by Ames (4) and Mercer, etal. (50), in their development of an ion-ex-change process to remove ammoniacal nitro-gen from sewage effluent.

Figure 6.—Types of Ion-Exchange Isotherms for the

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APPLICATIONS

Fertilizer and Soil Amendments

Based on their high ion-exchange capacityand water retentivity, natural zeolites havebeen used extensively in Japan as amendmentsfor sandy soils, and small tonnages have beenexported to Taiwan for this purpose (52,31),The pronounced selectivity of clinoptilolite forlarge cations, such as ammonium and potas-sium, has also been exploited in the prepara-tion of chemical fertilizers that improve thenutrient-retention ability of the soils by promot-ing a slower release of these elements for up-take by plants, In rice fields, where nitrogenefficiencies of less than 50 percent are not un-common, Minato (52) reported a 63 percent im-provement in the amount of available nitrogenin a highly permeable paddy soil 4 weeks af-ter about 40 tons/acre zeolite had been addedalong with standard fertilizer (figure 7), Turner(84), on the other hand, noted little change inthe vitrification of added ammonia when clin-

Figure 7.—Change of Soil Nitrogen of Paddy SoilWith Time

Vertical water seepage in soil = 1.35 cm/day (Yamagata PrefectureBoard of Agriculture and Forestry, 1966; reported in Minato, 1968.)

IN AGRONOMY

optilolite was mixed with a Texas clay soil, al-though the overall ion-exchange capacity of thesoil was increased. He attributed these conflict-ing results to the fact that the Japanese soilscontained much less clay, thereby accountingfor their inherent low ion-exchange capacityand fast-draining properties. The addition ofzeolite, therefore, resulted in a marked im-provement in the soil’s ammonium retentivity.These conclusions support those of Hsu, et al.(31), who found an increase in the effect of zeo-lite additions to soil when the clay content ofthe soil decreased. Although additions of bothmontmorillonite and mordenite increase thecation-exchange capacity of upland soils, thegreater stability of the zeolite to weathering al-lowed this increase to be retained for a muchlonger period of time than in the clay-enrichedsoils (22),

Using clinoptilolite tuff as a soil conditioner,the Agricultural Improvement Section of theYamagata Prefectural Government, Japan, re-ported significant increases in the yields ofwheat (13 to 15 percent), eggplant (19 to 55 per-cent), apples (13 to 38 percent), and carrots (63percent) when from 4 to 8 tons of zeolite wasadded per acre (83). Small, but significant im-provements in the dry-weight yields of sor-ghum in greenhouse experiments using a sandyloam were noted when 0.5 to 3.0 tons of clinop-tilolite per acre was added along with normalfertilizer (47). However, little improvement wasfound when raising corn under similar condi-tions. Hershey, et al. (29), showed that clinop-tilolite added to a potting medium for chrysan-themums did not behave like a soluble Ksource, but was very similar to a slow-releasefertilizer, The same fresh-weight yield wasachieved with a one-time addition of clinop-tilolite as with a daily irrigation of Hoagland’ssolution, containing 238 ppm K, for threemonths (total of 7 g potassium added), with noapparent detrimental effect on the plants (fig-ure 8).

Experiments by Great Western Sugar Co. inLongmont, CO, using clinoptilolite as a soilamendment, resulted in a significant increase

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Figure 8.— Yield of Chrysanthemums as a Functionof Potassium Level Supplied by One-Time Additions

of Clinoptilolite

tops also increased with the zeolite treatmentcompared with an ammonium sulfate control(table 2). These authors also found that natu-ral clinoptilolite added to soil in conjunctionwith urea reduced the growth suppression thatnormally occurs when urea is added alone (ta-ble 3). The presence of zeolites also resultedin less NO3-N being leached from the soil (fig-ure 9).

Both zeolite treatments apparently made con-siderably more ammonium available to theplants, especially when clay-poor soils wereemployed. The authors suggested that ammo-nium-exchanged clinoptilolite acted as a slow-release fertilizer, whereas, natural clinoptilo-lite acted as a trap for ammonium that was pro-duced by the decomposing urea, and therebyprevented both ammonium and nitrate toxic-ity by disrupting the bacterial vitrificationprocess. The ammonium selectivity of zeoliteswas exploited by Varro (85) in the formulationof a fertilizer consisting of a 1:1 mixture of sew-age sludge and zeolite, wherein the zeolite ap-parently controls the release of nitrogen fromthe organic components of the sludge.

Coupled with its valuable ion-exchange prop-erties which allow a controlled release of mi-cronutrients, such as iron, zinc, copper, man-

Table 2.—Growth Response of Radishes to Ammonium-Exchange Clinoptilolitea

130/0 clay soilb 6°/0 clay soilc

Parameter N H4-Clinoptilolite (NH4)2S 04 N H4-Clinoptilolite (NH4)2S 04

Leaf area (cm2/plant) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 187 187 150Plant weight (dry weight) (g). . . . . . . . . . . . . . . . . . . . . . . . . . . 1.84 1.12 1.40 1.1Root weight (g) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5 8.5 11.6 7.6N uptake (mg N/plant top) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57.2 35.9 42.6 38.9aLewis, et al., 1980.bPlants sampled 36 days after planting.cLeached five times; plants sampled 34 days after planting.

Table 3.—Growth Response of Radishes to Natural Clinoptilolite Plus Ureaa

13% clay soilb 6°/0 clay soilc

Parameter Zeolite + Urea Urea Zeolite + Urea Urea

Leaf area (cm2/plant) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 187 208 116Plant weight (dry weight) (g) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.59 1.23 1.38 0.71Root weight (g) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.8 12.4 6.3N uptake (mg N/plant top) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.5 38.6 44.4 18.9aLewis, et al., 1980.bPlants sampled 36 days after planting.cLeached five times; plants sampled 34 days after planting.

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Figure 9. —Cumulative Leachate N03-N for BandedNH4-Exchanged Clinoptilolite and Banded

Ammonium Sulfate (Lewis, et al., 1980)

135

issued to Aleshin, et a], (2), for grouting com-pound containing 3 to 5 percent clinoptiloliteto control herbicide percolation from irrigationcanals to ground waters.

Heavy Metal Traps

Not only do the ion-exchange properties ofcertain zeolites allow them to be used as car-riers of nutrient elements in fertilizers, they canbe exploited to trap undesirable metals and pre-vent their uptake into the food chain. Pulver-ized zeolites effectively reduced the transfer offertilizer-added heavy metals, such as copper,cadmium, lead, and zinc, from soils to plants(18). The selectivity of clinoptilolite for such

ganese, and cobalt, the ability of clinoptiloliteto absorb excess moisture makes it an attrac-tive addition to chemical fertilizers to preventcaking and hardening during storage and to an-imal feedstuffs to inhibit the development ofmold (82). Spiridonova, et a]. (78), found that0.5 percent clinoptilolite added to ammoniumnitrate fertilizer decreased caking by 68 percent.

pesticides, Fungicides, Herbicides

Similar to their synthetic counterparts, thehigh adsorption capacities in the dehydratedstate and the high ion-exchange capacities ofmany natural zeolites make them effective car-riers of herbicides, fungicides, and pesticides.Clinoptilolite can be an excellent substrate forbenzyl phosphorothioate to control stem blast-ing in rice (88). Using natural zeolites as a base,Hayashizaki and Tsuneji (26) found that clinop-tilolite is more than twice as effective as a car-rier of the herbicide benthiocarb in eliminat-ing weeds in paddy fields as other commercialproducts. Torii (82) reported that more than 100tons of zeolite were used in Japan in 1973 ascarriers in agriculture. A Russian patent was

ers (e. g., 74,19,1 1,76).

In view of the attempts being made by sani-tary and agricultural engineers to add munici-pal and industrial sewage sludge to farm andforest soils, natural zeolites may play a majorrole in this area also. The nutrient content ofsuch sludges is desirable, but the heavy metalspresent may accumulate to the point wherethey become toxic to plant life or to the ani-mals or human beings that may eventual] y eatthese plants. Cohen (12) reported median val-ues of 31 ppm cadmium, 1,230 ppm copper,830 ppm lead, and 2,780 ppm zinc for sludgesproduced in typical U.S. treatment plants. Zeo-lite additives to extract heavy metals may bea key to the safe use of sludge as fertilizer andhelp extend the life of sludge-disposal sites orof land subjected to the spray-irrigation proc-esses now being developed for the disposal ofchlorinated sewage. Similarly, Nishita andHaug (64) showed that the addition of clinop-tilolite to soils contaminated with radioactivestrontium (Sr90) resulted in a marked decreasein the uptake of strontium by plants, an obser-vation having enormous import in potentialtreatment of radioactive fallout that contami-nates soils in several pacific atolls where nu-clear testing has been carried out,

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APPLICATIONS IN ANIMAL HUSBANDRY

Animal Nutrition

Based on the successful use of montmorillo-nite clay in slowing down the passage of nu-triants in the digestive system of chickens andthe resultant improvement in caloric effieiency(73), experiments have been carried out in Ja-pan since 1965 on the application of naturalzeo1ites as dietary supplements for severaltypes of domestic animals. Because much ofthis work was superficial or not statistically sig-nificant, it has been repeated and enlargedupon in recent years by researchers in theUnited States and several other countries seek-ing agricultural applications for zeolites.

Poultry

Using clinoptilolite from the Itaya r-nine,Yamagata Prefecture, and mondenite fromKarawago, Miyagi Prefecture, Onagi (67) foundthat Leghorn chickens required less food andwater and still gained as much weight in a 2-week trial as birds receiving a control diet.Feed efficiency values (FEV) l were markedlyhigher at all levels of zeolite substitution; feed-stuffs containing 10 percent zeolite gave riseto efficiencies more than 20 percent greaterthan those of normal rations (table 4). Adverseeffects on the health or vitality of the birds werenot noted, and the droppings of groups receiv-ing zeolite diets contained up to 25 percent lessmoisture than those of control groups, after a

1 Weight gain/feed intake, excluding zeolite,

12-day drying period, making them conSider-ably easier to hand1e.

Broiler chickens fed a diet of 5 percent c1i-noptilite from the Hector, CA, deposit gainedslight1y 1ess weight over a 2-month period thanbirds receiving a normal diet, but average FEVS

were noticeably higher (table 5) (6). Perhaps ofgreater significance is the fact that none of the48 test birds on the zeolite diet died during theexperiment, while 3 on the control diet and 2on the control diet supplemented with antibi-otics succumbed. In addition to an apparentfeed-efficiecy increase of 4 to 5 percent, theprescnce of zeolite in the diet appears to havehad a favorable effect on the mortality of thebirds.

Hayhurst and Willard (27) confirmed manyof Onagi’s observations and reported small in-creases in FEV for Leghorn roosters over a 40-day period, especially during the first 10 days.The birds were fed a diet containing 7.5 per-cent clinoptilolite crushed and mixed directlywith the normal rations. Feces were noticea-bly dryer and less odoriferous. Unfortunate\,only 17 birds were used in the study and ex-tensive statistical evaluation of the resultscould not be made.

Swine

Kondo and Wagai (39) evaluated the use ofzeolites in the diets of young and mature York-shire pigs in 60- and 79-day experiments, re-

Table 4.—Caloric Efficiencies of Zeolite Supplements in poultry Feedinga

Z e o l i t e c o n t e n t A v e r a g e A v e r a g e A v e r a g e A v e r a g e Feed efficiencyGroup no. of rations starting wt. (g) final wt. (g) weight gain (g) feed intakeb (g) ratio c

1 . . . . . . . . . . . . . . . . . . . . 10 percent Cpd 553.7 795.6 241.9 668 0.3622 . . . . . . . . . . . . . . . . . . . . 5 percent Cp 540.7 778 237.3 697 0.3403 . . . . . . . . . . . . . . . . . . . . 3 percent Cp 556.7 796 239.3 748 0.3204 . . . . . . . . . . . . . . . . . . . . 10 percent Mo 532.3 757.3 225.0 634 0.3555 . . . . . . . . . . . . . . . . . . . . 5 percent Mo 552.3 814.6 262.3 775 0.3386 . . . . . . . . . . . . . . . . . . . . 3 percent Mo 534.5 791.3 256.8 769 0.3347 . . . . . . . . . . . . . . . . . . . . Control 556.5 789.3 232.8 782 0.298aOnagi (1966) Tests carried out on 48-day-old Leghorns over a 14-day period, 30 birds/group. Normal rations consisted of 16.5 Percent crude Protein and 66 Percent

digestible nutrientsbExcluding zeolite.cFeed efficiency - weight gain/feed intake (excluding zeolite).d Cp = clinoptilolite, Mo - mordenite.

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Table 5.—Apparent Caloric Efficiency of Zeolite in Chicken Rationsa

Average AverageTreatment of weight (g) consumption (g)—

4-week datad

Control diet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 730 1175Control diet + antibiotics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 708 1116Control diet with 5 percent clinoptilolite . . . . . . . . . . . . . . . . . . . . . . . . 703 1070

8-week dataf

Control diet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1869 3978Control diet + antibiotics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1882 3869Control diet with 6 percent clinoptilolite . . . . . . . . . . . . . . . . . . . . . . . . 1783 3647

Average Survivors ofF.E.V.C 48 birds

0.622 460.634 470.657 48

0.470 450.486 460.489 48

dStarter rations (O to 4 weeks)aAdapted from data of Arscott (1975)e55 ppm Zinc bacitracinbFeed consumed, excluding zeolite

CFeed efficiency value = weight/feed consumed (excluding zeolite) fFinisher rations (4 to 9 weeks)

spectively, and found that the weight gain ofanimals of both ages receiving diets contain-ing 5 percent clinoptilolite was from 25 to 2 9percent greater than that of animals receivingnormal diets (table 6). Feed supplemented withzeolites gave rise to feed efficiencies about 35percent greater than those of normal rationswhen fed to young pigs, but only about 6 per-cent greater when given to older animals. Inaddition, the particle size of the feces of thecontrol group was noticeably coarser than thatof the experiment group, suggesting that thedigestive process was more thorough whenzeolites were added to the diet. The feces ofanimals in the control group were also richerin all forms of nitrogen than zeolite-fed ani-mals, indicating that the zeolites contributedtoward a more efficient conversion of feedstuffnitrogen to animal protein.

The digestibility of crude protein and nitro-gen-free extracts tended to be improved as zeo-lite was substituted for wheat bran in swinediets at levels from 1 to 6 percent over a 12-week period (24,26). Anai, et al. (5), reportedsimilar results using 5 percent zeolite for 8 pigs

over a 12-week period and realized a 4-percentdecrease in the cost of producing body weight.They also noted a decrease in malodor andmoisture content of the excrement, Toxic orother adverse effects were not noted for anyof the test animals described. On the contrary,the presence of zeolites in swine rations ap-pears to contribute measurably to the well-being of the animals. Tests carried out on 4,000head of swine in Japan showed that the deathrate and incidence of disease among animalsfed a diet containing 6 percent clinoptilolitewas markedly lower than for control animalsover a 12-month period (83). As shown in ta-ble 7, the decrease in the number of cases ofgastric ulcers, pneumonia, heart dilation, andin the overall mortality is remarkable, The sav-ings in medicine alone amounted to about 75cents per animal, to say nothing of the in-creased value of a larger number of healthypigs.

In one test, the addition of zeolite to the dietof piglets severely afflicted with scours markedlyreversed the progress of this disease within afew days (53). Four underdeveloped Laundry

Table 6.—Caloric Efficiency of Zeolite Supplements in Swine Feeding a

Age of pigs Average weight

Start Finish Start Finish Average Average b Average c Zeolite(days) (kg) (kg) wt. gain (kg) feed intake (kg) F.E.V. improvement

Experimental d 60 120 15.43 44.43 29.00 85.0 0.341Control d 60 120 14.85 35.78 22.93 90.6 0.253 35 percentExperimentale 99 178 30.73 85.30 54.57 167.6 0.326Control e 99 178 31.20 73.50 42.30 136.2 0.308 6 percentaKOndo and Wagai (1968) Tests carried out using 5 percent clinoptilolite in rations of experimental groupsbExcluded zeolitecFeed efficiency value - weight gain/feed intake‘Eight Yorkshire pigseTwenty Yorkshire Pigs

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Table 7.—Effect of Zeolite Diets on Health of Swinea

Zeolite content Sickness causes Heart Mortality MedicinePeriod of rations Gastric ulcer Pneumonia dilatation rate (percent) cost/head

2/72 to 1/73 . . . . . . . . . ........0 77 128 6 4.0 $2.502/73 to 1/74 . . . . . . . . . ........6 percent clinoptilolite 22 51 4 2.6 $1.75aTest carried out on 4,000 swine at Keai Farm, Morioka, Iwate Prefecture, Japan (Torii, 1974)

pigs were fed a diet containing 30 percent zeo-lite for the first 15 days and 10 percent zeolitefor the remaining part of a month-long exper-iment. The severity of the disease decreasedalmost at once, and feces of all pigs were hardand normal after only 7 days. Although the pigsconsumed an average of 1.75 kg of zeolite perhead per day, no ill effects were noted, andonce they had recovered from diarrhetic ail-ments, the pigs regained healthy appetites andbecame vital. A recent Japanese patent disclo-sure claimed a method of preventing and treat-ing gastric ulcer in swine by the addition ofzeolite to their diets (49); supportive data, how-ever, were not reported.

Apparently the vitalizing effect of a zeolitediet can be transferred from mother to off-spring. Experiments at the Ichikawa LivestockExperiment Station, where 400 g of clinoptilo-lite was fed each day to pregnant sows and con-tinued through the 35-day weaning period oftheir offspring, showed substantial increase inthe growth rate of the young pigs, As shownin table 8, test animals weighed from 65 to 85percent more than control-group animals at theend of the weaning period (9). Young pigswhose dams received the zeolite diet also suf-fered almost no attacks of diarrhea, while thosein control groups were severely afflicted withscours, greatly inhibiting their normal growth.The addition of 5 percent zeolite to the rationsof pregnant sows 20 to 90 days after mating

gave rise to improved FEVs and increased lit-ter weight at parturition (46), The earlier thezeolite was added, the greater was the appar-ent effect.

Similar studies were conducted at OregonState University with young swine using ra-tions containing 5 percent clinoptilolite (16).Although lesser increases in growth rates werefound than in the Japanese studies, the inci-dence of scours was significantly reduced foranimals receiving the zeolite diet. Currently,heavy doses of prophylactic antibiotics areused to control such intestinal diseases, which,left unchecked, result in high mortality amongyoung swine after they are weaned. Federalregulations are becoming increasingly strin-gent in this area, and if antibiotics are prohib-ited, other means must be found to control suchdiseases. Natural zeolites may be the answer.

In a preliminary study involving 16 earlyweaned pigs over a 19-day period, animals onan antibiotic-free diet containing 10 percentclinoptilolite gained about 5 percent moreweight per pound of feed than those on a con-trol diet without antibiotics and about 4 per-cent more than those on an antibiotic-enricheddiet (table 9) (70). The small number of pigsused, however, limits the significance of thesefindings. In another study, a 30 percent im-provement in FEVs occurred for 35 young pigson a molasses-based diet when 7.5 percent

Table 8.—Effect of Prenatal Zeolite Diet on Newborn Pigsa

Average weight (kg)Species No. of pigs Group Newborn 21-days 35-days Weight gain improvementYorkshire 6 Experimental 1.25 4.3 7.83Yorkshire 10 Control 1.10 4.2 4.81 63 percentLaundry 6 Experimental 1.20 4.7 8.68Laundry 10 Control 1.10 4.0 4.67 96 percentaTest carried out at lchikawa Livestock Experiment station, Japan Four hundred grams of clinoptilolite given to sows n experimental group per day and continued

to end of weaning period (Buto and Takenashi, 1967)bweight-gain of experimental animals - weight-gain of control animals x 100.

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Table 9.—Effect of Zeolite Supplement in the Diets of Early Weaned Pigsa

Basal dietb Zeolite dietc Antibiotic dietd

Number of pigs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 4Average daily weight gain (g). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 245 304Feed efficiency value (FEV)e (weight gain/feed intake) . . . . . . . . . . . . . . 0.432 0.455 0.437aPond and Mumpton (1978b62% ground yellow corn 10% cerelose, 23% soybean meal, 0.5% salt, 0.5% Hopro R vitamin supplement, 1.5% ground limestone, 2.5% dicalcium phosphatecBasal diet less 10% cerelose plus 10°/0 clinoptilolite, -200 mesh, Castle Creek, IdahodBasal diet plus 0.3% Aurofac 10 antibiotic

eExcluding zeolite

clinoptilolite was substituted in the diet dur-ing the 35 to 65 kg growth period (table 10) (10).Feces of the zeolite-fed animals were also lessliquid than those on a control diet.

The addition of zeolites had little effect onthe FEVs in the 65 to 100 kg growth range.Heeney (28) supplemented normal corn-soy ra-tions of 36 pigs with 2,5 and 5 percent clinop-tilolite in a 120-day experiment (table 11). Hefound little overall difference in the FEVs; how-ever, for the first 30 days after weaning, FEVsof 0.455 and 0.424 were obtained for 2.5 and5.0 percent zeolite, respectively, comparedwith a value of 0.382 for the control animals,an increase of about 15 percent due to the pres-ence of zeolites in the diet. Little improvementwas noted between 30 and 120 days of thetreatment.

Ruminants

In an attempt to reduce the toxic effects ofhigh NH, + content of ruminal fluids whennonprotein nitrogen (NPN) compounds, such

as urea and diuret, are added to the diets of cat-tle, sheep, and goats, researchers introducedboth natural and synthetic zeolites into the ru-men of test animals (87). Ammonium ionsformed by the enzyme decomposition of NPNwere immediately ion exchanged into the zeo-lite structure and held there for several hoursuntil released by the regenerative action ofNa + entering the rumen in saliva during theafter-feeding fermentation period. Both in vivoand in vitro data showed that up to 15 percentof the NH 4 + in the rumen could be taken upby the zeolite. Thus, the gradual release ofNH4 + allowed rumen micro-organisms to syn-thesize cellular protein continuously for easyassimilation into the animals’ digestive sys-tems. The zeolite’s ability to act as a reservoirfor NH4 + “. . . permits the addition of supple-mental nitrogen to the animal feed while pro-tecting the animal against the production oftoxic levels of ammonia” in the rumen (87).

Clinoptilolite added to the feed of youngcalves improved their growth rate by stimulat-ing appetite and decreased the incidence of di-

Table 10.—Effect of Zeolite Supplement in Molasses-Based Diets of Young Pigsa

Zeolite level (%)

o 2.5 5 7.5 10

35-65 kg growth stage

Daily gain ( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 621 694 700 704 659Daily intake (g). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2900 3110 3090 2970 3040Daily feed intakec (g) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2900 3030 2940 2750 2740Feed efficiency value (FEV)d (weight gain/feed intake) . ............0.214 0.229 0.238 0.256 0.241

65-100 kg growth stages

Daily gain ( ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 541 582 526 562 535Daily intake (g). ., ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3550 3900 4260 4430 4140Daily feed intakec (g) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3550 3800 4050 4100 3730Feed efficiency value (FEV)d (weight gain/feed intake) . ............0.152 0.153 0.130 0.137 0.143aCastro and Elias (1978)blncluding zeoliteClntake less zeolite‘Excluding zeolite.

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Table 11 .—Effect of Clinoptilolite Supplemental in the Diet of Swinea

Control

Average initial weight (lb) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.6----

30-days:Average weight (lb)..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.0Average daily weight gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.09Feed/pound of gain (lb)b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.62Feed efficiency valuec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.382

60-days:Average weight (lb) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105.7Average daily weight gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.59Feed/pound of gain (lb)b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.80Feed efficiency valuec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.357

90-days:Average weight (lb) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153.7Average daily weight gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.72Feed/pound of gain (lb)b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.33Feed efficiency valuec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.300

120-days:Average weight (lb) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188.2Average daily weight gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.56Feed/pound of gain (lb)b. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.94Feed efficiency valuec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.254

OverallAverage daily weight gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.49Feed/pound of gain (lb)b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.42

2.50/oClinoptilolite

31.7

62.21.122.200,455

107.31.613.050.328

149.61.513.430.292

177.81.285,630.178

1.403.45

50/0Clinoptilolite-.

31.7

62.51.172.360.424

106.21,523.090.324

150.01,573.670.272

176.41.274.300.233

1.373.34

Feed efficiency-valuec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.292 0.290 0.299aFrom Heeney (1977), 6 pigs in each treatment. Control diet - 76.9% ground corn, 20% soybean 011 meal, 1.5% dicalcium phosphate, 0.5% CaCo3, 0.5% salt, 0.1%

trace mineral 0.25% vitamin premix, 025°/0 ASP250 antibiotic Zeolite diets contained 25 and 5°A replacement of corn.bExcluding zeoliteCWeight gain/feed Intake, excluding zeolite

arrhea and soft feces (38). Five percent zeolitewas added to the normal grass and hay dietsof lo-and 184-day-old heifer calves over a 180-day period. The animals on the zeolite-supple-mented diets gained approximately 20 percentmore weight than those in control groups, andalthough the test calves consumed more feed,the feeding costs per kilogram of weight gainedwere significantly less than for control animals.No deleterious effects were noted, and the fe-ces of the test animals contained slightly lesswater and fewer particles of undigested solids.The incidence of diarrhea and soft-feces wasmarkedly less in zeolite-fed calves than in con-trol animals (table 12)

Watanabe, et al. (86) raised six young bul-locks for 329 days on a diet containing 2 per-cent clinoptilolite, along with 72 percent digest-ible nutrients and 11 percent crude protein.Although little difference in the final weightsof test and control animals was noted, teststeers showed slightly larger body dimensionsand reportedly dressed out to give slightly high-

er quality meat. These differences were re-flected in the overall higher prices obtained forthe test animals and a 20 percent greater profit.In addition, diarrhea and other intestinal ail-ments were noticeably less prevalent in the ani-mals on the zeolitc diet, and the excrementfrom these animals was significantly less odor-iferous, again testifying to the retentivity ofclinoptilolite for ammonia. It is unfortunatethat a higher level of zeolite was not used inthese experiments; earlier studies in the UnitedStates showed that as much as 40 percent claycould be added to animal rations without ad-verse effects (68),

One study found increased protein digestionwhen 5 percent powdered clinoptilolite wasadded to a high-volubility protein diet of 18 Hol-stein steers and cows over a 118-day period;however, statistically significant weight in-creases were not noted, The addition of 2 per-cent zeolite to the rations of cows was effec-tive in preventing diarrhea and in increasingmilk product ion (20). These effects were appar-

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Table 12.–Occurrence of Diarrhea and Soft-Feces Among Calves on Diets Supplemented With5% Cl inopt i lo l i tea

—Incidence of diarrhea Incidence of soft-feces

Grass-fed Hay-fed Control Grass-fed H a y - f e d - C o n t r o l

30 . . . . . . . . . . . . . . . . . . . . . . . . . . 0 036-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 161-90 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O 091-120 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0121-150 . . . . . . . . . . . . . . . . . . . . . . . . . . . O 0151-184. . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0

4 0 0 42 9 4 132 1 1 131 2 0 134 4 0 80 0 0 0

Total 1 1aData summarized from Kondo et al (1969)

Excrement Treatment

In the Unitcd States, livestock productioncreates more than 1 billion metric tons of solidwastc and nearly 400 million tons of liquidwaste each year (43). Accumulations of suchmagnitude pose serious problems to the healthof man and beast alike and can pollute nearbystreams and rivers. In addition, the largeamount of undigested protein remaining in theexcrement represents a valuable resource thatfor the most part is being wasted because ofour growing dependence on chemical fertil-izers. The physical and chemical properties ofmany natural zeolites lend themselves to a widevariety of applications in the treatment of ani-mal wastes, including the:

c reduction of malodor and associated pol-lution,

c creation of healthier environments for con-fined livestock,

Q control of the viscosity and nutrient reten-tivity of the manure, and

c purification of methane gas produced by an-aerobic digestion of the excrement.

Malodor and Moisture Control

The semifluid droppings in large poultryhouses commonly emit a stench that is discom-forting to farm workers and to the chickensthemselves. The noxious fumes of ammoniaand hydrogen sulfide contribute to decreased

13 16 5 51—

reSistance to respiratory diseases and result insmaller and less healthy birds (15,35). In manyareas of Japan clinoptilolite is now mixed withthe droppings directly or packed in boxes sus-pended from ceilings to remove ammonia andthereby improve the general atmosphere inchicken houses (82). The net result is reportedto be an overall increase in egg production andhealthier birds.

One study used a zeolite-packed air scrub-ber to improve poultry-house environments(36). By passing ammonia-laden air over aseries of trays containing crushed clinoptilo-lite, 15 to 45 percent of the NH3-N was removedeven though the contact time was less than onesecond. There was an associated reduction inodor intensity. The use of such a scrubbercould improve the quality of the air in poultryhouses without the loss of heat that accompa-nies normal ventilation. The ammonium-loadedzeolite could then be used as a valuable soilamendment on disposal.

Water content, maggot population, and am-monia production can be all minimized whenchicken droppings are mixed with one-thirdzeolite (table 13). Similar results can be ob-tained if powdered zeolite is added directly tothe rations of the birds, all without affectingthe vitality or growth rate of the chickens (67).Apparently, gaseous ammonia reacts with thehydrous zeolite to form ammonium ions thatare selectively ion-exchanged and held in thezeolite structure. These experiments suggestthat the addition of zeolites to poultry wastescould reduce labor costs associated with air-drying or the high energy costs of thermal treat-

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Table 13.—Effect of Zeolite Additions toChicken Droppings

Property 2.1 3:1 5:1 10,1 Control

Moisture content (%) 123 131 134 157 185Maggot content (counts per

unit area) 38 101 172 387 573Ammonia generation (relative

quantities) 315 370 245 500 450aOnagi (1965) Clinoptilolite was spread on droppings of Leghorn chickens

every third day for a 15-day period The total amount of droppings iS the samein all tests, Including the control

ment, whilc at the same time retain the valu-able fertilizer components and meet ecologi-cal standards.

In swine raising, pigs fed a diet containing10 percent cinoptilolite had feces richer in allforms of nitrogen after drying than those fromcontrol groups (vide supra) (39). As a result ofthis study and of other investigations, about 25tons of clinoptilolite per month is spread onthe floors of a Sapporo swine-raising facilityto adsorb urine and other liquid wastes (82).The buildings were said to be dry, clean, andconsiderably less odoriferous. In Akita Prefec-ture, Japan, a zeolitic mudstone is used to treatoffensive odors and to reduce moisture contentof swine excrement (30). The dried manure isthen sold as an inexpensive rice fertilizer.

An innovative application of zeolites in ex-crement treatment was patented and involvesthe addition of a natural zeolite and ferrous sul-fate to chicken droppings (37), The ferrous sul-fate inhibits zymosis and decomposition of thedroppings, and the zeolite stabilizes the hygro-scopic nature of this compound and capturesN H4 + produced in the manure. The mixtureis dried at 1200 to 1500 C and used as an odor-less, organic fertilizer, It is also used as a pro-tein-rich feedstuff for fish, fowl, and domes-tic animals.

Methane Purification

Although it is well known that anaerobic di-gestion of animal excrement and other organicwastes produces an impure methane-gas prod-uct, this source of energy has generally beenignored for anything except local or in-houseuse (32). One major drawback is the fact thatin addition to methane, copious quantities ofcarbon dioxide and sulfur compounds are also

produced during the digestion process, givingrise to low-Btu products that are extremely cor-rosive. Nevertheless, the process is still an at-tractive one, and Goeppner and Hasselmann(21) estimated that a billion cubic feet of 700Btu/ft 3 methane gas could be produced by treat-ing the 250,000 tons of manure produced eachday in the United States. The methane pro-duced by the anaerobic digestion of the organicwastes of a typical New York State dairy farmof 60 head may be equivalent to the farm’s en-tire fossil-fuel requirements (32).

A recent development of Reserve SyntheticFuels, Inc., using the adsorption properties ofnatural zeolites, suggests that this methane canbe economically upgraded to high-Btu prod-ucts. In 1975, this company opened a methane-recovery and purification plant to treat meth-ane gas produced by decaying organic matterin the Pales Verde landfill near Los Angeles,As shown schematically in figure 10, raw gascontaining about 50 percent methane and 40

Figure 10. —Methane-Purification System,Pales Verde Landfill

Page 19: Using Zeolites in Agriculture

143

percent carbon dioxide is fed to two pretreat- feet of methane meeting pipeline specificationsment vessels to remove moisture, hydrogen sul- is produced each day and delivered to localfide, and mercaptans. The dry gas is then utility companies (65). Such a zeolite-adsorp-routed through three parallel columns packed tion process to upgrade impure methane pro-with pellets of dehydrated chabazite/erionite duced by the digestion of animal manure ap-and carbon dioxide is removed by adsorption pears to be technically feasible and awaitson the zeolite. Approximately 1 million cubic detailed economic and engineering evaluation.

AQUACULTURAL APPLICATIONS

In recent years, more and more fish productshave found their way to the dinner tables andfeeding troughs of every country, and the com-mercial breeding and raising of fish as a sourceof protein is becoming a major business in theUnited States and other countries, Many vari-eties of fish, however, are extremely sensitiveto minor fluctuations in such factors as watertemperature, pH, O2, H2S, and NH4+. Thechemical and biological environment of aqua-cultural systems must be maintained withinclose limits at all times. Processes based on theselective adsorption and ion-exchange proper-ties of several natural zeolites for oxygen aer-ation of hatchery and transport water and forthe removal of toxic nitrogen from tanks andbreeding ponds may contribute significantly toincreased product ion for human and animalconsumption.

Nitrogen Removal From Closedor Recirculation Systems

In closed or recirculating aquacultural sys-tems, NH4 + produced by the decompositionof excrement and unused food is one of theleading causes of disease and mortality in fish.I n oxygen-poor environments, even a fewparts-per-million NH4 + can lead to gill dam-age, hyperplasia, and substantial reduction ingrowth rates (42). Biological vitrification is acommon means of removing NH4 + from cul-ture waters; however, processes similar tothose used in municipal sewage-treatmentplants based on zeolite ion exchange have beenfound to be effective in controlling the nitro-gen content of hatchery waters (40). Zeolite ion

exchange might be a useful alternative to bio-filtration for NH4+-removal and have the ad-vantages of low cost and high tolerance tochanging temperatures and chemical condi-tions (33).

Unpublished tests conducted in 1973 at aworking hatchery near Newport, OR, indicatedthat 97 to 99 percent of the NH, + producedin a recirculating system was removed by clinop-tilolite ion-exchange columns (34). Trout alsoremained healthy during a 4-week trial whenzeolite ion exchange was used to regulate thenitrogen content of tank waters (69), Becker In-dustries of Newport, OR, in conjunction withthe U.S. Army Corps of Engineers, has devel-oped a single-unit purification facility forhatchery-water reuse. The system incorporatesa zeolite ion-exchange circuit for nitrogen re-moval and is designed to handle typical con-centrations and conditions encountered atmost of the 200 fish hatcheries operating in thePacific Northwest (34).

A similar ammonium-ion removal systemusing zeolite ion exchange for fish haulage ap-plications, where brain damage due to excessNH, + commonly results in sterility, stuntedgrowth, and high mortality has also been de-veloped (63). Three-way cartridges and filterscontaining granular clinoptilolite will also beavailable for home aquaria. The U.S. Fish andWildlife Service investigated zeolite ion-ex-change processes for the treatment of recircu-lating waters in tank trucks used to transportchannel catfish from Texas hatcheries to theColorado River in Arizona (48). If NH4+ canbe removed, the number of fish hauled in suchtrucks can be nearly tripled.

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Aeration Oxygen Production

Oxygen-enriched air can be produced by theselective adsorption of nitrogen by activatedzeolites. A pressure-swing adsorption processcapable of producing up to 500 m 3 of 90 per-cent oxygen per hour was developed in Japanfor secondary steel smelting (80). Smaller gen-erators with outputs of as little as 15 liters of50 percent O2 per hour are also manufacturedand used to aerate fish breeding tanks and inthe transportation of live fish. Carp and gold-fish raised in such environments are said to belivelier and to have greater appetites (41), Inclosed tanks and stagnant ponds, oxygen aer-ation could markedly increase the number offish that could be raised per unit volume.

Oxygen produced by small, portable unitscontaining natural zeolite absorbents could beused to replenish free oxygen in small lakeswhere eutrophication endangers fish life. Fast,et al. (1 7), showed that the oxygen of hypolim-nion zones could be increased markedly by aer-ation using liquid O2 as a source. Haines (23)demonstrated side-stream pumping could im-prove the dissolved oxygen in the hypolimnionof a small lake in New York State.

Fish Nutrition

The high-protein rations used in commercialfish raising are quite expensive and their costhas been a limiting factor in the development

of large-scale aquacultural operations. Thephysiology of fish and poultry is remarkablysimilar, and if the results achieved with chick-ens can be duplicated with fish, the substitu-tion of small amounts of inexpensive zeolitesin normal fish food, with no adverse changein growth and perhaps a small increase in feedefficiency, could result in considerable savings.The quality of the water in recirculating sys-tems should also be improved by the use of zeo-lite-supplemented food, as should that of theeffluents. Leonard (44) reported preliminary re-sults of experiments where 2 percent clinop-tilolite was added to the normal 48 percent pro-tein food of 100 rainbow trout: after 64 days,a 10 percent improvement in the biomass in-crease was noted, with no apparent ill effectson the fish (table 14).

Table 14.—Effect of Clinoptilolite Additions to theDiet of Trouta

Control Test100% normal 98% normal feed

feedb 2% clinoptilolite

Average starting weight (g) 10.2 10.1Average 64-day weight 48,6 52.3Average weight gain 38.4 42,2Mortalitv. ... ~ ~ 4 3a100 rainbow trout.bStandard 48% protein fish food

OCCURRENCE AND AVAILABILITY OF NATURAL ZEOLITES

Geological Occurrence other hand, are ideally suited for simple, inex-

Since their discovery more than 200 years pensive, open-pit mining.

ago, natural zeolite minerals have been widely Most sedimentary zeolite deposits of eco-recognized by geologists as cavity and fracture nomic significance were formed from fine-fillings in almost every basaltic igneous rock. grained volcanic ash or other pyroclastic ma-Attractive crystals up to several centimeters in terial that was carried by the wind from ansize adorn the mineral museums of every coun- erupting volcano and deposited onto the landtry; however, such traprock occurrences are surface, into shallow freshwater or saline lakes,generally too low-grade and heterogeneous for or into the sea fairly close to the volcaniccommercial extraction. The flat-lying and near- source. Much of the land-deposited materially monomineralic sedimentary deposits, on the was quickly washed into lakes where it formed

Page 21: Using Zeolites in Agriculture

beds of nearly pure ash. Successive eruptionsresulted in sequences of ash layers interstrati-fied with normal lake or marine Sediments,such as mudstoncs, silt stone, sandstones, andlimestones, as well as beds of diatomite, ben-tonite, and chert (figure 1 I).

The layers of volcanic ash (called volcanictuff) vary in thickness from less than a centi-metcr to several hundred meters and maystretch for 10 kilometers. Many of these bed-ded tuffs have been transformed almost com-pletely into well-formed, micrometer-size zeo-litc minerals. Zeolitically altered tuffs occur inrelatively young sedimentary rocks in diversegeological environments. Sedimentary zeolitedeposits of this kind have been classified intothe following types, with many gradations be-tween the types, Sheppard (77), Mumpton (54),and Munson and Sheppard (62):

1.

2.

3.4.

5.

6.

7.

145

deposits formed from volcanic materialsin hydrologically ‘ c l o s e d " s a l i n elake systems;deposits formed in hyrdrologially ‘open”fresh-water lake or ground watcr systems;deposits formed in marine environments;deposits formed by low-grade, burial meta-morphism;deposits formed by hydrothermal or hot-spring activity in bedded Sediments:deposits formed from volcanic materialsin alkaline soils;deposits formed without direct evidenceof volcanic precursors.

The most common zeolites in sedimentarydeposits are analclime, chabazite, c1inoptilolite,erionite, heulandite, laumontite, mordenite,phillipsite, and wairakite, with clinoptiloliteranking first in abundance. Except for heulan-

Figure 11.— Field Exposure of Zeolite Beds

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dite, laumontite, and wairakite, “sedimentary”zeolites are alkalic and are commonly more si-licic than their igneous counterparts. Commer-cial interest is mainly in deposits of the firstfour types. Zeolite tuffs in saline-lake depositsare generally a few centimeters to a few metersthick and commonly contain nearly monomin-eralic zones of the larger pore zeolites, erioniteand chabazite that are relatively uncommon inother types of deposits. “Open-system” depos-its and marine tuffs deposited close to theirsource are generally characterized by clinop-tilolite and/or mordenite and may be severalhundred meters thick. Zeolitic tuffs are com-monly soft and lightweight, although somehard, siliceous deposits of clinoptilolite andmordenite are known. Many sedimentary zeo-lite beds contain as much as 95 percent of asingle zeolite species, while others consist oftwo or more zeolites with minor amounts ofcalcite, quartz, feldspar, montmorillonite clay,and unreacted volcanic glass.

Most zeolites in sedimentary rocks crystal-lized from volcanic ash by reaction of the amor-phous, aluminosilicate glass with pervadingpore waters derived either from saline lakes ordescending ground waters. Others originatedby the alteration of preexisting feldspars, feld-spathoids, biogenic silica, or poorly crystallineclay minerals. Although the exact mechanismof formation is still under investigation, zeo-lites in sedimentary rocks probably crystallizedas well-formed, micrometer-size crystals bymeans of a dissolution-reprecipitation mech-anism, with or without an intermediate gelstage (55) (figure 12).

The factors controlling whether a zeolite ora clay mineral formed or which of several zeo-lites formed from a given starting material arealso only poorly understood, although temper-ature, pressure, reaction time, and the concen-trations of the dissolved species, such as H+,silica, alumina, and alkali and alkaline earthelements, seem to be paramount in importance.Early formed species also tend to react furtherwith pore fluids of different composition, there-by yielding even more complex assemblages.

Figure 12.–Scanning Electron Micrograph ofClinoptilolite Laths With Minor Mordenite From a

Saline-Lake Deposit Tuff Near Hector, CA(from Mumpton and Ormsby, 1976)

Geographic Distribution

The distribution of zeolite deposits in vari-ous geographic regions of the world is gov-erned solely by the geology of those regions.Regions that have undergone past volcanic ac-tivity are likely to contain significant depositsof zeolite minerals. Although the zeolite phil-lipsite is known to have formed within the last10,000 years in a small saline-lake deposit atTeels Marsh, NV (79) by the alteration of vol-canic ash from the explosion of Mt. Mazuma(Crater Lake), and chabazite has been identi-fied in deposits on the walls of ancient Romanbaths in France, most potentially commercialdeposits of zeolites are of Tertiary or lowerPleistocene age (70,000 to 3 million years ago).Thus, any part of the Earth that was subjectedto volcanic activity during this period undoubt-edly contains extensive deposits of volcanicash, and if these ash deposits had an opportu-nity to react with percolating ground watersor alkaline pore waters from former salinelakes, beds of high-grade zeolites are apt toexist.

Although zeolites are now considered to besome of the most abundant and widespread au-

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147

thigenic silicate minerals in sedimentary rocks,their existence as major constituents of alteredvolcanic tuffs is still not common knowledgeamong the geologists of many countries. Be-cause of their inherently fine crystal size, zeo-lites are not easily identified by ordinary micro-sscopic techniques and have often been missedby geologists and mineralogists studying theseformations. In general, zeolite identification re-quircs sophisticated X-ray diffraction and elec-tron microscopic equipment not available inmany geological laboratories; however, oncea particular soft, lightweight, clay-like rockfrom a particular area is identified in the lab-oratory as a zeolite rock, similar materials areeasy to locate in the field.

Table 15 lists the countries where zeoliteshave been reported from sedimentary rocks ofvolcanic origin and estimates the chances ofdiscovering additional deposits in these coun-tries. Sedimentary zeolites have been found onevery continent, although few have been re-ported from the Middle East, Latin America,or the East Indies, mainly because geologistsin these regions generally have been unawareof the widespread occurrence of zeolites inaltered volcanic tuffs. Wherever zeolites havebeen found, however, man has used the soft,lightweight tuffs for hundreds of years as eas-ily carved stone in a variety of structures rang-ing from walls and foundations of buildings tobarns and corrals to house livestock. Zeoliticblocks have been found in buildings associatedwith the Mayan pyramids at Monte Alban andMitla in southern Mexico (56) and are usedtoday in the construction of modern dwellingsin the Tokaj region of eastern Hungary. Zeo-lites are mined in only a dozen countries (ta-ble 16), but the potential is much greater.

The high probability of finding minable de-posits of zeolites in countries where they havenot yet been reported, but where there has beenconsiderable volcanic activity in the past, is il-lustrated by the discovery of major bodies ofsedimentary zeolites in Mexico and in centralTurkey in the early and late 1970s, respectively.Both countries show promise of becoming ma-jor suppliers of mineral raw materials in theyears to come, but, as with most developing na-

tions, they have only limited in-house geologi-cal expertise to service their blossoming min-eral industry.

During the late 1950s and 1960s the geologi-cal similarity}’ of the Western United States andnorthern Mexico led geologists to speculateabout the existence of zeolite deposits south ofthe border. It was not until 1972, however, thatthis author (56) discovered the first such de-posit in southern Oaxaca after visiting a largestone quarry during an unrelated project. Therock was being used as a local dimension stoneand closely resembled zeolitic tuffs that werebeing quarried in Japan. Subsequently, the Oax-acan rock was shown to consist of about 90percent clinoptilolite and mordenite. Shortlythereafter, several similar deposits were discov-ered in this part of Mexico and Mexican scien-tists quickly learned to recognize zeolitic tuffsin the field. One deposit was spotted in a roadcut while driving past it at 50 miles per hour,suggesting that many more await discoverywith only minimal exploration efforts. As a re-sult of these discoveries, at least three other de-posits of sedimentary zeolites have been foundin the northern part of the country by Mexi-can geologists who are now atune to the exis-tence of zeolites in volcanogenic environmentsand to their potential applications in industrialand agricultural technology.

Similar to Mexico, major parts of the centralAnatolian region of Turkey are covered bythick sequences of Tertiary volcanic rocks, but,with the exception of a few minor occurrencesof analcime in saline-lake environments, re-ports of zeolites in the volcanogenic sedimen-tary rocks of this country have been rare. Theprincipal reason for this is simply lack of ex-ploration combined with a lack of knowledgeabout the potential applications of such mate-rials in industry. Turkey’s few geologists havebeen more occupied with their chrome andborate resources, which are exported in largequantities to acquire badly needed currency.In 1977, however, several low-grade occur-rences of erionite and chabazite were uncov-ered in Turkey’s Cappadocia region, along witha major deposit of clinoptilolite (7). In 1979, asecond major deposit was discovered by the au-

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Table 15.— Reported Occurrences of Sedimentary Zeolites

Zeolite . —Country species

Minable Minor Chances fordeposit occurrence finding deposit

Europe:BelgiumBulgaria

CzechoslovakiaDenmarkFinlandFranceGermany

Great Britain

Hungary

Italy

PolandRomaniaSoviet Union

Spain

Switzerland

Turkey

Yugoslavia

North America:Canada

Cuba

GuatemalaMexico

PanamaWest Indies

Africa:AngolaBotswanaCongoEgyptKenya

LaumontiteClinoptiloliteMordeniteAnalcimeClinoptiloliteClinoptiloliteLaumontiteClinoptiloliteChabazitePhillipsiteAnalcimeAnalcimeClinoptiloliteLaumontiteClinoptiloliteMordeniteChabazitePhillipsiteAnalcimeClinoptiloliteClinoptiloliteClinoptiloliteMordeniteChabaziteAnalcimeLaumontiteClinoptiloliteMordeniteClinoptiloliteLaumontiteClinoptiloliteErioniteChabaziteAnalcimeClinoptiloliteAnalcimeMordeniteErionite

LaumontiteClinoptiloliteClinoptiloliteMordeniteClinoptiloliteClinoptiloliteMordeniteAnalcimeErionitePhillipsiteClinoptiloliteWairakiteClinoptilolite

ClinoptiloliteClinoptiloliteAnalcimeHeulanditePhillipsiteErionite

xxxx

x

xxxx

xxxxxxxxx

xxxxxxxxx

xx

xxxxxx

xxxxxxxx

x

x

x

xx

x

x

xxxxx

xxxxx

x

xxxxxxxx

xxxx

x

xx

x

x

xx

xx

x

PoorExcellentExcellentPoorGoodPoorPoorGoodGoodGoodPoorPoorPoorPoorExcellentExcellentExcellentExcellentGoodExcellentExcellentExcellentExcellentGoodGoodGoodGoodGoodPoorPoorExcellentExcellentExcellentExcellentExcellentGoodExcellentGood

PoorGoodExcellentExcellentExcellentExcellentExcellentGoodExcellentExcellentExcellentPoorExcellent

GoodGoodGoodGoodExcellentExcellent

Page 25: Using Zeolites in Agriculture

149

Table 15.— Reported Occurrences of Sedimentary Zeolites—Continued

Zeolite Minable Minor Chances forCountry species deposit occurrence finding deposit

Northwest Africa AnalcimeMordeniteClinoptilolite

Republic of South Africa AnalcimeClinoptilolite

Tanzania ErioniteChabazitePhillipsiteAnalcimeClinoptilolite

x GoodGoodExcellentPoorExcellentExcellentExcellentExcellentExcellentExcellent

x

xx

xxxxxxx

Asia:IranIsraelPakistanAustralia

ClinoptiloliteClinoptiloliteAnalcimeClinoptiloliteAnalcimeClinoptiloliteLaumontiteAnalcimeClinoptiloliteMordeniteAnalcimeLaumontiteWairakiteClinoptiloliteAnalcimeClinoptiloliteMordeniteLaumontiteErioniteLaumontite

x ExcellentExcellentGoodGoodGoodExcellentPoorGoodExcellentExcellentPoorPoorPoorExcellentGoodGoodExcellentGoodGoodPoor

xxx

x

xxx

ChinaFormosa x

xJapan xxx

xxxxx

KoreaNew Zealand

xxx

xxxxx

Oceania

South Africa:Argentina

x

ClinoptiloliteAnalcimeLaumontiteClinoptilolite

xxx

ExcellentExcellentPoorExcellent

xxChile

Antarctica:Antarctica Laumontite

Phillipsitexx

PoorPoor

thor (59) and R. A. Sheppard of the U.S. Geo-logical Survey, accompanied by a Turkish ge-ologist, with a minimum of field effort. Thisindicates a widespread distribution of such ma-terials in volcanogenic sedimentary rocks inthis country.

face deposits overlain by a few to no more than25 meters of overburden. The zeolite beds areusually flat-lying and vary only slightly in thick-ness along the length of the deposit. Shallowdrilling is usually required to outline the areasof highest grade, but many deposits are minedby simple projection of the bed behind the out-crop, Commonly, the exposed bed can be bro-ken in the mine by bulldozers or rippers; inplaces small amounts of blasting are required.In thinner deposits, care must be taken to elim-inate overlying and underlying clays and vol-canic ash from the ore to preserve purity, butin some of the thicker deposits this poses noproblem,

Mining and Milling

The mining of zeolites in bedded sedimen-tary deposits is a relatively straightforwardprocess requiring only a minimum of equip-ment and trained personnel. Almost all of theknown zeolite deposits being mined are sur-

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Table 16.—Countries Engaged in Zeolite Mininga

Country M i n e r a l -—

Mines Remarks

United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Mexico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cuba . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Japan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Korea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bulgaria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Hungary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Soviet Union . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Yugoslavia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .South Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Italy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .aAs of 1980

ClinoptiloliteChabaziteErioniteMordeniteMordenite/ClinoptiloliteClinoptiloliteClinoptiloliteMordeniteClinoptiloliteClinoptiloliteClinoptiloliteMordeniteClinoptiloliteMordeniteClinoptiloliteClinoptiloliteChabazite/PhillipsiteChabazite/Phillipsite

12421118521113121

Processing the raw ore is dependent on theenvisioned end use. Water-purification appli-cations require a fine-sand fraction that mustbe prepared from the ore by crushing andscreening whereas fertilizer and animal nutri-tion uses will likely make use of finely pow-dered material. In general, preparation in-volves only crushing, screening, and bagging.Where particle size is critical, the screenedproduct must be washed to remove undersizematerial and then dried. More sophisticated ap-

Agronomic Applications

Many more available.Single deposit, four companies.

Estimated.Estimated.

Estimated.Estimated.Estimated.Several more available.

Numerous, used for construction.Several, used for construction.

plications may require that the zeolite he ion-exchanged to an ammonium or potassium formbefore being shipped to the consumer. In suchcases, the pulverized and screened productmust be subjected to a series of washes withchloride or sulfate salts of these elements,washed with water to e1iminate excess salts,filtered, dried, and bagged. In 1980, crushedore could be produced i n the United States forabout $30 to $40/ton.

DISCUSSION

Although zeolites have been used for manyyears in Japan as soil amendments, they areonly now becoming the subject of serious in-vestigation in the United States as slow-releasefertilizers, moisture-control additives to low-clay soils, traps for heavy metals, carriers ofpest icicles, fungicides, and herbicides, and de-caking agents in fertilizer storage. As soilamendments they appear to retain moistureand i reprove the overall ion-exchange capac-it y of sandy and volcanic soils. Studies are be-ing carried out on both pure zeolite and on zeo-lite that has been pretreated with nutritiveelements, such as potassium or ammonium. In

either case, the zeolite appears to act as a slow-release fertilizer, selectively holding such ele-ments in its structure for long periods of time,thereby increasing the efficiency of such ad-ditives and reducing the total cost of fertiliza-tion. Although the data available are not une-quivocal, the greatest success appears to havebeen with root crops such as sugar beets, car-rots, and radishes, where nitrogen is a vital nu-trient. The optimum level of application, how-ever, must still be determined for various typesof soils and for the particular crop in question,as must the frequency and exact mode of ap-plication, the optimum particle size of the zeo-lite, and the nature of chemical pretreatmentof the zeolite.

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Table 17 lists organizations that have or areconducting experiments on the use of naturalzeolites in agronomic applications.

Animal Nutrition Applications

Despite the lack of statistical significance, nu-merous studies strongly suggest that the addi-tion of certain zeolite mincrals to the diets ofswine, poultry, and ruminants results in de-cided improvement in growth and in feed effi-ciency (weight gain/pounds of nutritional feedconsumed). In addition, the incidence of intes-tinal disease among young animals appears tobe less when zeolites are part of the daily diet,The most dramatic results have been reportedby overseas workers where experiments mayhave been conducted under conditions thatwere somewhat less sanitary than those gen-erally employed in the United States. Zeolite-supplemented diets appear to be most benefi-

cia1 in swine during the first 30 to 60 days af-ter weaning, although there is some evidenceto suggest that zeolites in the rations of preg-nant sows contributc to increased litter weightsand healthier offspring. In Japan, 2 to 5 per-cent clinoptilolite in the diets of cattle appearedto result in larger animals and fewer incidencesof diarrhea. One study in the United Statesfound a 12-percent increase in feed efficiencyfor cattle during the first 37 days using only1.25 percent zeolite.

The exact function of the zeolites in both die-tary and antibiotic phenomena are not well un-derstood and await serious ph}’biological andbiochemical investigation. The ammonium se-lectivity of clinoptilolite suggests that inruminants it acts as a reservoir for ammoniumions produced by the breakdown of vegetableprotein and nonprotein nitrogen in rations, re-leasing it for a more efficient synthesis intoamino acids, proteins, and other nitrogenouscompounds by micro-organisms in the gastro-intestinal (GI) lumen, From the concentrationof ammonia in the portal blood of weanling ratsfed a 5 percent clinoptilolite diet or dosed oral-1y with this zeolite, Pond, et al. (71), postulatedthat the zeolite bound free ammonia in the GItract, thereby preventing its buildup to toxiclevels in the system. Such an antibiotic effectcould indeed be responsible for the largergrowths recorded for zeolite-fed animals.

Table 18 lists organizations that have or areconducting experiments on the use of naturalzeolites in animal nutrition applications,

Table 17.—Organizations Engaged in Zeolite/Agronomic Investigationsa

Organizations Crop Organization Crop

Department of Horticulture Radishes Agricultural Experiment Station CornColorado State University New Mexico State University SorghumFort Collins, Colorado Las Crucas, New MexicoDepartment of Agronomy Sorghum Department of Plant Science RadishesColorado State University Corn University of New Hampshire CornFort Collins, Colorado Wheat Durham, New HampshireDepartment of Environmental Chrysanthemums Texas Agricultural Experiment Rice

HorticuIture StationUniversity of California Texas A&M UniversityDavis, California Beaumont, TexasU.S. Sugarcane Field Laboratory Sugarcane Department of Soils, Water NitrogenU.S. Department of Agriculture and Engineering retentionHouma, Louisiana Tucson, Arizona in soilsaAs of 1980

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Table 18.—Organizations Engaged in Animal Nutrition Studies Using Zeolitesa

Organization Animal Organization Animal

Department of Poultry ScienceColorado State UniversityFort Collins, ColoradoDepartment of Animal ScienceColorado State UniversityFort Collins, ColoradoClayton Livestock Research Center

New Mexico State UniversityClayton, New MexicoDepartment of Poultry ScienceOregon State UniversityCorvallis, OregonLivestock Nutrition ServiceWestminster, CaliforniaDepartment of Animal ScienceUniversity of VermontBurlington, VermontU.S. Meat Animal Research CenterU.S. Department of AgricultureClay Center, NebraskaDepartment of Animal SciencePennsylvania State UniversityUniversity Park, Pennsylvania

Chickens

Swine

Beef Cattle

Chickens

Cattle

Ruminants

Rats (swine)

Cattle

Department of Animal ScienceCornell UniversityIthaca, New YorkDepartment of Animal ScienceOregon State UniversityCorvallis, OregonWestern Washington Research and Ex-tension

CenterWashington State UniversityPuyallup, WashingtonDepartment of Animal ScienceUniversity of KentuckyLexington, KentuckyFood and Animal Research, Inc.Juneau, WisconsinDepartment of BiologyCleveland State UniversityCleveland, OhioDepartment of Agricultural EngineeringOregon State UniversityCorvallis, Oregon

Swine

SwineRabbits

DairyCattle

Calves

Calves

ChickensSwine

Odor control

a As o f 1980 .

Excrement Treatment Applications

Although the results are difficult to quantify,almost all studies of the use of zeolites as die-tary supplements in animal rations have re-ported a noticeable decrease in excrement mal-odor and have attributed this observation to thehigh selectivity of the zeolite in the feces forthe ammonium ion. Similar results were notedwhen zeolites were added directly to cattlefeedlots, suggesting that not only can healthierand less odoriferous environments be achievedby the addition of zeolites to animal manure,but that the nitrogen-retention ability of the ma-nure can be improved as well.

Zeolite purification of low-Btu methane pro-duced by the anaerobic fermentation of excre-ment and other agricultural waste products

may be a means of producing inexpensive en-ergy on individual farms or in small commu-nities, and zeolite ion-exchange processes maybe employed in the removal of ammonium ionsfrom recirculating or closed aquacultural sys-tems, thereby allowing more fish to be raisedor transported in the same volume of water.Aquacultural research of this type has been oris being conducted by Becker Industries, New-port, OR; the U.S. Fish and Wildlife Service,Fish Cultural Development Center, Bozeman,MT; Jungle Laboratories, Comfort, TX; the De-partment of Fisheries and Wildlife, New Mex-ico State University, Las Crucas, NM; the Nar-ragansett Marine Laboratory, University ofRhode Island, Kingston, RI; and the Depart-ment of Zoology, Southern Illinois University,Carbondale, IL.

CONCLUSIONS AND RECOMMENDATIONS

Although they have been used locally for sev- tives to animal rations, and in the treatmenteral years in Japan and other parts of the Far of agricultural wastes is still in the experimen-East in small amounts, the use of zeolites as tal stage in the United States. A number of agri-soil amendments, fertilizer supplements, addi- cultural organizations have or are investigat-

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ing such uses for natural zeolites in thiscountry. The projects have generally beensponsored by grants or contracts from compa-nies that themselves are developing applica-tions for zeolites in one or more areas of tech-nology, or they have been funded by theinstitutions themselves and make use of zeo-lite products provided free or at low cost bythe companies. Table 19 summarizes the agri-cultural research efforts of companies that holdproperties of natural zeolites. In addition,other, nonproperty holding organizations, suchas International Minerals & Chemical Corp.,Cargill, Inc., and Lowe’s, Inc., have also beeninvolved in the development of uses of natu-ral zeolites in agriculture.

Overseas, six to eight agricultural stations inJapan continue to investigate natural zeolitesas soil amendments and dietary supplements;Pratley Perlite Mining Co., which owns a largec1inoptilolite deposit in South Africa, has madeseveral studies of the use of zeolites in the ra-tions of swine and poultry; and a recent Bul-garian-Soviet symposium on natural zeolitescontained seven papers on animal-nutrition ap-plications and two on soil-amendment uses,

‘Second Bulgaria n-%t’iet Symposium on Natu ra] Zeolites,Kardzhali, Bulgaria, Oct. 11-14, 1$)79,

Similar projects are in progress in Cuba andHungary, where deposits of clinoptilolite andmordenite are abundant. The intense interestin the several socialistic countries mentionedabove undoubtedly stems from their efforts touse their own natural resources and therebyreduce their dependency on foreign sources ofexpensive fertilizers and animal rations. Thesesame objectives, of course, are desired by eachdeveloping nation—maximum use of local rawmaterials and minimal use of imported prod-ucts that must be purchased with hard curren-cy. Where they can be found within a particu-lar nation or where they can be obtained fromneighboring countries at minimum cost, nat-ural zeolites have the potential to increase theagricultural productivity of that nation by re-ducing the need for or increasing the efficiencyof chemical fertilizers and animal feedstuffs.

To convert the agricultural promise of natu-ral zeolites into commercial reality, a concertedeffort must be made in the United States andelsewhere by both the private sector and byState and Federal funding organizations. Thestudies to date have been mainly of a prelimi-nary nature—radishes have been grown insteadof potatoes, and rats have been raised insteadof beef cattle—or of limited duration or extent.

Table 19.—Zeolite Property Holders and Zeoagricultural Research Efforts

Organization Zeolite Speciesa Research Effort

Anaconda Company Clinoptilolite, Erionite, In-house; sponsoredChabazite/Erionite, Clinoptilolite, Chabazite, Mor-denite, Phillipsite

Colorado Lien Co. Clinoptilolite SponsoredDouble Eagle Petroleum & Mining Co. Clinoptilolite, Clinoptilolite SponsoredForminco Clinoptilolite NoneHarris & Western Corp. Clinopti/elite/A40rdenite NoneLadd Mountain Mining Co. Erionite/Clinoptilolite NoneLeonard Resources Clinoptilolite SponsoredLetcher Associates ClinoptiloliteMinerals Research

NonePhillipsite None

Minobras, Inc. Erionite NoneMobil Oil Corp. Erionite NoneMonolith Portland Cement Co. Clinoptilolite NoneNL Industries Clinoptilolite NoneNorton Co. Chabazite/Erionite, Ferrierite NoneNRG Corp. Chabazite/Erionite NoneOccidental Minerals Corp. Clinoptilolite, Clinoptilolite, Erionite In-house; sponsoredRocky Mountain Energy Co, ClinoptiloliteUnion Carbide Corp.

SponsoredChabazite/Erionite, Mordenite, Erionite In-house; sponsored

U.S. Energy Corp. Clinoptilolite NoneW. R. Grace & Co. Chabazite/Erionite, Ferrierite NoneaRoman type = working mines, italics = prospects

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Little information has been developed to illum-inate the long-term benefits or adverse impactson food production. Many of the companiessponsoring this research have considered theresults proprietary, and rightfully so, but work-ers in the field are therefore unable to obtainthe latest information, a situation that often re-sults in massive duplication of effort. Large-scale testing of zeolites under sustained fieldconditions and projects involving statisticallysignificant numbers of animals are greatlyneeded at this juncture. Such projects will re-quire continuous funding by State and Federalagencies, or perhaps, international agencies ifthe results are to be applied to developing na-tions. It would be extremely instructive to carryout such testing in several developing nationsthemselves, where agricultural practices arenot as finely tuned as in the United States.

The actual introduction of natural zeolitesinto specific agricultural processes should poseno major problems. Crushed and sized mate-rial could be added to the fields directly orbanded into the soil either alone or with nor-mal fertilizers using standard equipment. Like-wise, the zeolite could be mixed as a powderor fine granules with normal feedstuffs pro-vided for livestock, or be inserted as a bolusinto the stomachs of ruminants. It could alsobe sprinkled on or mixed with manure accumu-lations on a daily basis for nutrient retentivity.

None of these processes would require spe-cial machinery; in fact, all could be carried outby hand, if such were the common practice inthat country. Users would, of course, need tobe instructed as to the correct amount to ap-ply to fields or to mix with normal rations, andthe optimum time to apply it for specific crops,and considerable educational efforts may benecessary to convince the small farmer of thebenefits of zeolite additives. In this regard, zeo-lites are no different than any innovative pro-cedure that many farmers are slow to accept.

Because the use of zeolites in agriculturalprocesses has not yet reached the proven orcommercial stage, any scenario developed tointroduce this promising technology into de-veloping nations would involve contributions

from both the United States and the develop-ing nations. The contribution of the UnitedStates would be both geological and agricul-tural expertise in zeolite technology, whereasthe contribution of the developing nationswould be a willingness to search for depositsof zeolites and a willingness to carry out somenecessary long-term or large-scale testing un-der field conditions. Any implementation planshould begin with a series of visits by a teamof zeolite experts from the United States toselected developing nations in the world wherezeolites are known or have a high probabilityof occurring. In addition to a leader who wouldhave a broad background in zeolite technology,the team would consist of four to eight geolo-gists, agronomists, animal nutritionists, andagricultural engineers who are not only experi-enced in the use of zeolites in agriculture orin the occurrence of zeolites in volcanogenicsedimentary formations, but who can incite anenthusiasm in others for the wonderful thingsthat zeolites can do. The team would include:

c

a geologist who is not only knowledgea-ble about the occurrence of zeolites in suchenvironments, but who is capable of work-ing with local resource people to find andevaluate potential deposits of zeolites inthese countries;an agronomist or plant scientist with con-siderable experience in the use of zeolitesto improve crop productivity;an animal nutritionist with the necessaryexpertise in the use of zeolites as dietarysupplements in animal nutrition; andan agricultural engineer who has workedwith zeolites in excrement treatment to im-prove the health of confined livestock orthe ammonium retentivity of animal wastes.The agricultural engineer would also pro-vide practical experience to the team.

Prior to the first visit to a developing nation,the team would arm itself with the latest infor-mation in the field by visiting the leading ex-periment stations and research laboratories inthis country and abroad where zeoagriculturalinvestigations are being carried out, Specialemphasis would be placed on the recent workin Japan and in countries of Eastern Europe.

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It is vital that the introduction of zeoagricul-ture into a developing nation not end with thevisit of a team of U.S. experts. On the contrary,the initial visit should be folloed up as soonas possible with specific plans for implement-ing the technology into the nation’s agriculturalprocesses. Although the implementation sce-nario of all innovative technologies would ap-pear to be similar from this point on, the zeo-lite scenario would involve a search for thesematerials in the developing nation if such ma-terials had not already been reportrd from thatcountry. Such exploration would probably becarried out by the local geological survey ormining agency, but should be assisted in thefield by a geologist familiar with the occur-rence of zeolites. If zeolites are known in thecountry or if they can be obtained from neigh-boring regions without difficulty, plans shouldbe made with the country's agricultural peo-ple to field test the technology under optimumconditions. Such plans and tests should alsobe made with the assistance of agronomists oranimal scientists already familiar with the useof zeolites in these processes.

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