Zeolite, Bentonite, Diatomaceous earth, Kaolin: Which mineral for which job?

Zeolite, bentonite, diatomaceous earth: why they are so often confused

The confusion is entirely understandable. Zeolite, bentonite, diatomaceous earth and kaolin look similar; they are all natural and inert, and their uses overlap in many areas: soil improvement, animal feed additives, detoxification, and plant sprays. In practice, however, each ‘works’ through a completely different mechanism — some via ion exchange, others via swelling, others via mechanical friction, and others via a protective film. Once you understand the mechanism, the choice becomes easy.

Each in a single sentence

🪨 Zeolite (clinoptilolite)

Crystalline aluminosilicate with a ‘cage-like’ structure filled with pores of a constant diameter. It works primarily through ion exchange and adsorption: it binds ammonia, heavy metals and positively charged ions, whilst also retaining and gradually releasing water and nutrients. It does not swell on contact with water — it retains its structure.

🧱 Bentonite (mainly montmorillonite)

Laminated (stratified) clay derived from volcanic ash. Its characteristic feature: it swells significantly when exposed to water, opening up the space between its layers and dramatically increasing the binding surface area. It has a high cation-exchange capacity and is particularly effective at binding aflatoxins. Sodium bentonite can absorb 12–15 times its volume in water.

🦴 Diatomaceous earth

Fossilised shells of microscopic algae (diatoms), consisting mainly of amorphous silicon dioxide. Its effect on insects is mechanical, not chemical: its sharp, porous microstructures scratch the insect’s waxy exoskeleton and absorb its lipids, leading to dehydration. Because the mechanism is physical, insects do not develop resistance.

⚪ Kaolin

White clay. In agriculture, it is used as a ‘particle film’: when sprayed in solution, it forms a white, protective film on leaves and fruit. This film reflects solar radiation (protection against sunscald and heat stress) and deters insects from laying eggs or feeding.

Comparison table at a glance

What task? Which mineral

If you want the short answer before getting into the details, start with the task at hand and see where it leads. The sections that follow explain in detail why this is the case in each instance.

Soil & nutrition → Zeolite

For soil improvement, zeolite is the obvious choice. Thanks to its microporous structure, it acts as a ‘reservoir’ for water and nutrients: it retains moisture and trace elements (such as nitrogen and potassium) and releases them gradually to the roots, reducing the wastage of fertilisers and water. Bentonite, on the other hand, due to its swelling properties, can adversely affect aeration and drainage in certain soils — it serves more as a sealant (e.g. in lakes/reservoirs) than as a nutrient enhancer.

Insects on plants → Diatomaceous earth or kaolin (depending on the objective)

Here, the choice depends on the problem. diatomaceous earth is a contact insecticide: it acts by mechanical abrasion/dehydration on insects with ‘hard’ or hairy bodies that walk on the dust (e.g. beetles, ants in stored produce). Kaolin acts preventatively: the white film makes the fruit ‘invisible’ or unattractive to adult insects and reduces egg-laying — which is why it is particularly popular against the olive fruit fly, where studies have shown seasonal protection lasting over 14 weeks. It should be noted that zeolite has also been used as a protective film/repellent on leaves; consequently, in olive cultivation, zeolite and kaolin are often regarded as alternatives based on the same principle.

Animal feed & mycotoxins → Bentonite & Zeolite

In animal feed, both bentonite and zeolites are used as mycotoxin binders — they trap the toxins so that they are not absorbed by the animal. However, there is one important difference: bentonite (montmorillonite) is the most well-documented binder, particularly for aflatoxins, with very high binding rates. zeolites cover a broader spectrum (ammonia, heavy metals) and also help to bind aflatoxins. In practice, many formulations combine the two.

Human detoxification → Zeolite & Bentonite

Both are used in human detoxification, with a slightly different ‘philosophy’. zeolite (clinoptilolite) is distinguished by its selective ion exchange and thermal stability, targeting specific toxins and heavy metals without significantly affecting the absorption of nutrients. Bentonite has a strong negative charge and a large surface area, with particularly well-documented efficacy against aflatoxins. This is why certain products (such as Zeobent) combine zeolite and bentonite, to achieve a broader spectrum of binding.

Odours & hygiene → Zeolite

For odours (cat litter trays, stables, animal living areas), zeolite is the pre-eminent choice, as it immediately binds ammonia — the main source of odour — via ion exchange, before it becomes a smell. diatomaceous earth absorbs moisture and grease, but does not have the same selective action on ammonia. This is why cat litter and odour-neutralising products are mainly based on zeolite.

Can I use them together?

Yes — and it often makes sense, as the mechanisms are complementary. In detoxification, the combination of zeolite and bentonite covers a broader spectrum of toxins (selective ion exchange + strong binding of aflatoxins). For plants, you can use zeolite in the soil (for nutrition and moisture retention) and diatomaceous earth or kaolin on the foliage (for insects). The key is to understand the role each plays, so that you do not pay for overlapping effects.

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