Which Harmful Elements Can Zeolite Bind in Soil? What Research Shows
Natural zeolite is often described as a mineral that "cleans" soil. That is not quite accurate. Zeolite does not remove harmful elements from the soil. It binds them in place, so less of them dissolves in the soil water and less reaches plant roots. For farmers and soil-remediation projects, that is often what matters most: lower metal content in the crop.
How zeolite binds metals
Zeolite is a porous mineral with a negatively charged framework. Positively charged ions are held on its surface and inside its pores. Many heavy metals in soil are present as positive ions, such as cadmium (Cd²⁺), lead (Pb²⁺), zinc (Zn²⁺) and copper (Cu²⁺). When zeolite holds these ions, they become less mobile and less available to plants.
What published studies show
Cadmium and lead in maize and barley (USA). In a pot study at the University of Georgia, natural zeolite at 15 g per kg of soil in most cases significantly reduced cadmium and lead uptake by maize and barley (Chlopecka & Adriano, 1997).
Cadmium near lignite mine dumps (Bosnia and Herzegovina). In a field study, zeolite significantly reduced cadmium mobility in the soil. Maize leaves from zeolite-treated plots contained less heavy metals than leaves from untreated plots (Murtić et al., 2020).
Lead, cadmium and zinc in heavily polluted soil (Italy). Of three amendments tested, zeolite was the most effective at reducing cadmium uptake by white lupin. Plants on zeolite-treated soil grew 1.8 times more above-ground biomass than on untreated soil (Castaldi et al., 2005).
Heavy metals in leached chernozem (Russia). Researchers at Ulyanovsk State Agrarian University found that natural zeolite applied at 5 t/ha reduced the mobility of heavy metals in the soil (Razenkov & Kulikova).
Which elements: the short answer
Cadmium: the strongest and most consistent evidence.
Lead and zinc: reduced in several studies, but usually less than cadmium.
Copper: some studies show an effect, but the data are thinner.
The limits
Zeolite is not always the strongest option. In a Czech study, lime and synthetic zeolite reduced cadmium, lead and zinc uptake more than natural zeolite did. In a Romanian field trial near a former smelter, natural zeolite lowered available cadmium, lead and zinc, but other amendments lowered them more. Zeolite works best as part of a plan, often together with liming or compost.
Rates are higher than for fertility. For yield, typical rates are 200–500 kg/ha. For binding metals, studies used about 5 t/ha in the field and up to 1.5% of soil mass in pots.
Results depend on the rock. The type and amount of zeolite minerals, soil pH and the level of pollution all affect the result. Most studies above used clinoptilolite-rich zeolite. Test the material on your own soil before a large project.
Our activated natural zeolite
Israway supplies thermally activated natural zeolite from the Tatar-Shatrashan deposit (Tatarstan, Russia). The product is covered by an EAEU declaration of conformity.
Fractions for soil use: 0.2–0.8 mm, 0.8–2.5 mm and 2.5–5 mm; other fractions on request
Packaging: big bags of 700–800 kg, depending on the fraction, or 25 kg bags on pallets, 1 tonne per pallet
Minimum order: 20 tonnes
More about soil use: Zeolite for agriculture.
For remediation projects and soil-improver blends, we can send a sample for your own soil test.
Sources
Chlopecka A., Adriano D.C. Influence of zeolite, apatite and Fe-oxide on Cd and Pb uptake by crops. Science of the Total Environment, 1997, 207: 195–206.
Murtić S. et al. In situ immobilisation of heavy metals in soils using natural clay minerals. Plant, Soil and Environment, 2020, 66(12): 632–638.
Castaldi P., Santona L., Melis P. Heavy metal immobilization by chemical amendments in a polluted soil and influence on white lupin growth. Chemosphere, 2005, 60(3): 365–371.
Razenkov I.V., Kulikova A.Kh. Effect of filtration sediment and zeolite on heavy metal mobility in leached chernozem and winter wheat yield. Ulyanovsk State Agrarian University.
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