The Horticultural Use of Zeolite

Horticultural Use of Zeolite as in a Salad Crop
Horticultural Use of Zeolite as in a Salad Crop

The interest in the horticultural use of Zeolite in recent years is particularly high.

And this is justified by the growing interest in exploiting the kind of natural resources that contribute to the increase of agricultural production – and consequently of the agricultural income – with the lowest possible environmental costs.

Scientific research and studies show that Zeolite can actually contribute in this direction.

In fact, the Zeolite HEU-type, that is, the Clinoptilolite with the Heulandite.

The horticultural use of Zeolite is also the main subject of this article of ‘Kalliergeia‘. The other uses of the Zeolites, such as the one concerning the increase of collective IQ of its editorial team, will be the subject of a forthcoming, strictly eschatological, tribute.

Sources of Natural Zeolites

Natural Zeolite is found in so-called Zeolite tuffs. A Zeolite tuff is nothing but the rock and the rock layers containing the natural Zeolites. These rock and layers are the geological product of volcanic action on the parent material.

Zeolite tuffs of volcaniclastic rock deposits may contain one or more natural Zeolites.

The various phases of natural Zeolites have so far numbered 67, of which only 9 have found a safe and productive scope. Of these, again, only two, the Clinoptilolite and the Heulandite, are considered to be the most suitable to be used for agricultural and horticultural use

Horticultural Use of Zeolite

Quality Characteristics of Natural Zeolites Suitable for Horticultural Use

The horticultural use of Zeolite HEU-type takes place on the basis of certain qualities of the Zeolite tuffs.

These quality characteristics can be grouped into two main categories: the first includes those specific features that are necessary – which make the natural Zeolites suitable for a variety of agricultural and horticultural applications.

The second includes those features that increase the quality of zeolite minerals and for this reason are desirable.

Necessary Zeolite Quality Characteristics

The necessary traits that a Zeolite tuff must possess in order to be suitable for use in horticulture include:

  • The complete absence of Zeolite fibrous form (such as, for example, erionite, mordenite, mazzite and mesolite)
  • The absence from the deposit of other also fibrous form of minerals (tiny needles)
  • The content of the deposit in HEU-type Zeolite (i.e., Heulandite and Clinoptilolite) in an amount greater than 80 wt%
  • The complete absence from the deposit of swelling clay minerals to prevent pozzolanic action
  • The mineral content of clay at ≤ 20 wt%
  • The content of microporous minerals, ie HEU-type Zeolite, aluminate minerals and mararay, at ≥86%
  • The content of non-microporous minerals (quartz, christobalite, tridymite, opal, alkali feldspars and placoclases) ≤ 14%
  • The concentration of the main elements, trace elements and radionuclides in such quantities that they do not exceed the Concentrations (MAC) of trace elements in agricultural soils, as defined by the relevant legislation

If even one of these traits is absence, then the agricultural & horticulture use of the Zeolite HEU-type contained in this tuff is prohibitive.

Desirable Zeolite Quality Features

Among the desirable features of the Zeolite tuff, which increase the value of Zeolite’s suitable for agricultural and horticulture use, include:

  • The greater than 170 meq/100g cationexchange capacity (C.E.C.)
  • The concentration of bioavailable metals, trace elements and radionuclides should be located within the crystalline structure instead of the concentration on the surface of Zeolite crystal frameworks
  • Less than 1% bioavailability and leachability ofdangerous-harmful metals as well as trace elements, chemical compounds and radionuclides
  • The presence of K, Ca, Mg and Na as the main cations exchangeable in the zeolitic tuff

Horticultural Use of Zeolite

Horticultural Use of Zeolite as Substrate for Succulent Cuttings
Horticultural Use of Zeolite as Substrate for Succulent Cuttings

The Natural Zeolite HEU-Type

The most suitable form for the agricultural use of Zeolite – as mentioned above – is mainly that of the HEU-type, that is, the Clinoptilolite with the Heulandite. This form of Zeolite minerals is characterized by:

  • The microporous and mesoporous that are created by the 8-ring porous and the 10-ring porous of their crystalline lattice
  • Their rather average composition, since the Si/Al ratio is between 3 and 5 (Intermediate Silica Zeolite)

Both of these elements reflect specific properties, such as the size of available spaces, affecting adsorption and desorption of molecules or the ratio of Silicon to Aluminum
related to the cation exchange capacity of minerals but also the ability to adsorb polar molecules.

Horticultural Use of Zeolite

Qualitative Grading of Natural Zeolite HEU-Type

Depending on the content of Zeolite tuffs in Clinoptilolite and Heulandite, the Zeolites are distinguished in:

  • Poor Quality when the HEU-type Zeolite is less than 55%
  • Low Quality when the HEU type Zeolite is present at a rate ranging between 56 and 65%
  • Moderate Quality, when the HEU type Zeolite is contained in a percentage ranging between 66 and 75%
  • High Quality when the HEU type Zeolite is contained in a percentage ranging between 76 and 85%
  • Very High Quality when the HEU type Zeolite is contained in more than 85%

Suitable and desirable for agricultural & horticultural use Zeolites are those characterized as High and Very High Quality.

Horticultural Use of Zeolite

The Horticultural Use of Zeolite

HEU-type Zeolite, and the natural products derived from them, can be utilized in many sectors, factors, and phases of horticultural production. This is possible because the agricultural and horticultural use of Zeolite produces remarkable results with respect to soil, irrigation, fertilization and plant protection as well as yields of cultivated plants.

And all this is largely due to:

  • The microporous and mesoporous of HEU-type Zeolites, which can reach up to 50% of their dehydrated minerals
  • Their high cation exchange capacity
  • The selective immobilization of heavy metals and cations
  • The high content of HEU-type Zeolites in silicon and aluminum oxides

Horticultural Use of Zeolite

Plants Comparison by Soil Mixture with & Without Zeolite. Left Pansy Plant with Zeolite in Soil Mixture has Richer Root System.
Left Pansy Plant with Zeolite in Soil Mixture has Richer Root System

The Effect of Natural Zeolites on Soil

The addition of natural Zeolite to the soil improves its physical and chemical characteristics. More specifically:

  • Stabilizes and increases beneficial soil aggregates
  • Improves the consistency of the light soils and lighting the texture of the heavy ones
  • It increases the cation exchange capacity of soil and soil solution
  • It tends to regulate the pH of the soil to neutral
  • It contributes to the depollution of soils by the reducing of heavy metals, toxins and radionuclides
  • Increases the fertility of soils

Horticultural Use of Zeolite

The Effect of Natural Zeolites on Irrigation of Crops

The use of natural zeolite in the field of irrigation of crops, results in the saving of water and its more efficient use. More specifically:

  • Improves the soil water-holding capacity, especially in the sandy textured ones
  • It gradually delivers the stored water to the crops
  • It directly delivers stored water to plants that are under water stress conditions

Horticultural Use of Zeolite

The Effect of Natural Zeolites on the Fertilization of Crops

The HEU-type Zeolites have a beneficial effect on the quantitative and qualitative
fertilization of the cultivated plants. More specifically:

  • Applying to the soil, they retain and do not allow the leaching of the nutrients
  • They gradually deliver nutrients to plants
  • They can contribute to reducing the amount of fertilizer in crops
  • By taking on the composition of special fertilizers, they also gradually yield the necessary nutrients for the plants

Horticultural Use of Zeolite

The Effect of Natural Zeolites on Plant Protection

The horticultural use of Zeolite has an extremely interesting plant protection effect against a range of phytopathogenic parasites and physiological diseases.

  • Its high content of silicon and aluminum oxides enhances the plant disease resistance (‘immune system’) against a number of phytopathogenic parasites
  • It deals with a significant degree of certain phytopathogens responsible for the occurrence of rots in plants when applied to the soil as water soluble
  • It does a considerable deal of certain fungi and insects when applied to the plants by foliage spray
  • By taking on the composition of specific biological preparations, it increases its plant protection against fungal infections of plants
  • Protects from sunscald and freezing crops to a remarkable extent when applied by foliage spray

Horticultural Use of Zeolite

Horticultural Use of Zeolite in Tomato Crop - Institute of Sustainable Irrigated Agriculture Tatura Victoria, in Australia
Horticultural Use of Zeolite in Tomato Crop - Institute of Sustainable Irrigated Agriculture Tatura Victoria, in Australia

The Effect of Natural Zeolite on Crops

The horticultural use of Zeolite, rated both in the areas of yield and improvement of the quality characteristics of the crop products, is considered justified. With the promise from the editorial team of ‘Kalliergeia‘ for another specialized article (…When pigs fly) about on the specific use of Zeolite in individual crops, here is just mentioned that:

  • The addition of natural Zeolite to the soil and in quantities of 5000 to 30000 kilograms per hectare, can lead to an increase in yield – depending on the conditions and cultivation – from 17 to 95%
  • The observed improvement in the quality characteristics of agricultural and horticultural products can range between 4 and 46%

Horticultural Use of Zeolite


The References to yet another exhaustively comprehensible article on ‘Kalliergeia’, which is proudly titled The Horticultural Use of Zeolite, are respectively proudly presented by the (not Zeolithic) rock band The Rolling Stones with the song of the greatest Willie Dixon ‘Little Red Rooster‘.

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Horticultural Use of Zeolite


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