Natural Zeolite for Organic Soil Improvement | Slow-Release NH₄⁺·K⁺ Retention

Q: Is it safe to use natural zeolite in certified organic cultivation without jeopardizing certification?

KMIZEOLITE clinoptilolite is a natural mineral that has only been crushed and screened, with no synthetic treatment or chemical modification. It is OMRI Listed (KMI-10365, NOP Allowed) and is covered by the U.S. EPA pesticide tolerance exemption (40 CFR 180.1001). It can therefore be applied as a soil amendment in certified organic cultivation. However, because material-list registration requirements may differ among certification bodies, it is safest to present the OMRI listing documentation to your certification consultant for confirmation before application.

Q: Does zeolite replace chemical fertilizers, or does it improve fertilizer efficiency?

Zeolite itself contains almost no N, P, or K, so it is not a fertilizer but a soil amendment that holds nutrients in place. The negatively charged sites of its CEC 1.6–2.0 meq/g reversibly retain ammonium (NH4+) and potassium (K+) that have been mineralized from compost and organic fertilizers, reducing leaching and ammonia volatilization losses and supplying nutrients gradually as a slow-release effect. As a result, the same amount of organic nutrients is used more efficiently.

Q: Besides ammonium (NH₄⁺), does it also capture nitrate (NO₃⁻) and phosphorus (P)?

No. The nutrient-retention action of natural clinoptilolite is cation exchange occurring on its negatively charged framework, so it is strong toward positively charged nutrients such as ammonium (NH4+), potassium (K+), and calcium (Ca2+), but it cannot directly adsorb negatively charged nutrients such as nitrate (NO3-) and phosphate (PO4 3-). For nitrate and phosphate, there is only an indirect effect in which leaching is somewhat slowed by improved soil water retention. Therefore, unmodified natural zeolite should be considered with a focus on holding nitrogen at the pre-nitrification stage through NH4+ retention; to directly load and slow-release anionic nutrients (such as phosphorus), a surfactant-modified zeolite (SMZ) form with the surface modified by a cationic surfactant is required separately.

Q: How much, and at what particle size, should I apply per 10a (about 0.1 ha)?

It varies by soil texture and crop, but generally a basal application to the cultivation layer is considered in the range of 200–1,000 kg per 10a, with the upper end applying to sandy soils that have lower retention capacity. Powder (100 mesh, under 150μm), which mixes evenly with the soil and acts immediately, is suitable for basal application and compost blending, while Fine Granule (30×50 mesh) is considered when surface retention and dust reduction are needed. The exact amount is best determined through soil testing and a small-area pilot.

Q: Once applied, how long does the effect last?

Zeolite does not biodegrade in soil and retains its ion-exchange sites, so there is no need to reapply the full amount every cropping season; the nutrient- and water-retention effects accumulate and persist across multiple seasons. As reported in studies such as He et al. (2002), it remains in the soil and acts to reduce ammonia volatilization, so it is used as a material that builds a long-term foundation for soil nutrient-retention capacity.

Why nutrient loss occurs in organic soils

Because organic farming cannot use chemical fertilizers or synthetic nitrogen sources, it relies on organic matter such as compost, liquid manure, and green manure to supply crop nutrients. However, nitrogen mineralized from organic matter exists mainly in the form of ammonium (NH₄⁺) and nitrate (NO₃⁻), and in sandy or fast-draining soils it is rapidly leached away with irrigation and rainfall or volatilized as ammonia (NH₃) and lost. This is the core cause of the reduced nutrient efficiency that organic farmers often experience — "I applied plenty of fertilizer, but crop growth doesn't keep up."

Especially in light soils with low cation exchange capacity (CEC), there are too few negatively charged sites to hold nutrients, so even the additional organic nutrients applied fail to stay in the crop root zone and run off into groundwater. A mineral soil amendment that raises the soil's own nutrient-retention capacity without synthetic materials therefore becomes a candidate for consideration.

How it works: nutrient retention by cation exchange

Natural clinoptilolite carries a permanent negative charge created as Al³⁺ isomorphously substitutes for Si⁴⁺ sites in its framework. To offset this negative charge, exchangeable Na⁺·K⁺·Ca²⁺ cations occupy the framework channels, and these sites form the retention reservoir of cation exchange capacity (CEC) 1.6–2.0 meq/g. As mineralized ammonium and potassium increase in the soil solution, they exchange with the channel cations according to the law of mass action and become bound to the framework; when root uptake lowers the solution concentration, they are again released reversibly. This reversible adsorption–release cycle is the essence of slow-release behavior, supplying nutrients gradually throughout the cropping season rather than losing them all at once.

Among exchangeable cations, clinoptilolite has a high selectivity for ammonium (NH₄⁺) (a typical selectivity sequence: K⁺ ≈ NH₄⁺ > Na⁺ > Ca²⁺), making it advantageous for preferentially retaining mineralized and applied ammonium in the soil. Its two-dimensional micropore channels of 4.0–7.0 Å serve as passages through which hydrated cations and water molecules move together, raising soil water-holding capacity at the same time as nutrient retention. The key point is that this retention effect is cation exchange occurring on a negatively charged framework. Therefore, unmodified natural zeolite is strong toward cations (NH₄⁺·K⁺·Ca²⁺) but cannot directly adsorb anions such as nitrate (NO₃⁻) and phosphate (PO₄³⁻). Anionic nutrients are only retained indirectly through leaching delay due to improved water retention; to capture anions directly, separate cationic-surfactant modification (SMZ) is required.

Why it is considered as an organic soil amendment — quantitative evidence

Field research supports this mechanism quantitatively. He et al. (2002, Plant and Soil) reported that mixing clinoptilolite into a calcareous sandy soil significantly reduced ammonia volatilization losses of urea and ammonium fertilizers, so that nitrogen was retained in the soil longer (He et al., 2002, Plant and Soil). In studies mixing clinoptilolite directly into soil, reduced nitrate leaching and improved plant growth were observed together, interpreted as a result of zeolite retaining NH₄⁺ and reducing the nitrogen pool lost through nitrification (Influences of clinoptilolite on nitrate leaching and plant growth, J. Hazard. Mater., 2011). Container (potting-soil) experiments likewise confirmed that zeolite-amended media improve both nutrient retention and plant growth (McConnell et al., 2001, HortTechnology).

Comprehensive reviews point in a consistent direction. Jarosz et al. (2022, Applied Sciences) summarized that applying zeolite as a soil amendment improves nutrient use efficiency (NUE) and crop yield while reducing fertilizer leaching (Jarosz et al., 2022), and Cataldo et al. (2021, Agronomy) broadly reviewed effects on soil physical properties, water retention, and CEC improvement (Cataldo et al., 2021). Ramesh & Reddy (2017, Water, Air, & Soil Pollution) reviewed its role as a sustainable-agriculture aid that simultaneously improves water and nutrient retention (Ramesh & Reddy, 2017), and cases were also reported in which zeolite application increased yield in alternate wetting and drying (AWD) rice systems (Sci. Total Environ., 2022).

KMIZEOLITE's natural clinoptilolite is 97% pure, mined and processed at the Amargosa Valley mine in Nevada, USA, and remains a mineral that has only been crushed and screened, with no synthetic treatment or chemical modification. For this reason it is OMRI Listed (KMI-10365, NOP Allowed) and covered by the U.S. EPA pesticide tolerance exemption (40 CFR 180.1001), so it can be applied in certified organic cultivation (the FDA GRAS basis for general uses such as soil improvement is 21 CFR 182.2729, and for animal feed intake use it is 21 CFR 582.2729). With a specific surface area of 40.0 m²/g, a stable pH range of 3.0–10.0, and a hardness of 4.0–5.0 Mohs, it does not decompose and remains stable in both acidic and alkaline soils.

KMIZEOLITE Key Properties

Item	Value
Clinoptilolite purity	97%
Cation exchange capacity (CEC)	1.6–2.0 meq/g
Specific surface area	40.0 m²/g
Pore diameter	4.0–7.0 Å
Stable pH range	3.0–10.0
Hardness	4.0–5.0 Mohs
Thermal stability	700°C
Specific gravity	1.89
Bulk density	45–54 lbs/ft³
Certifications	OMRI KMI-10365, FDA GRAS, TSCA, EN-71-3

Organic soil-improvement application examples

Below are representative application methods in which natural zeolite is considered for certified organic cultivation. All focus on raising the soil's nutrient- and water-retention capacity without synthetic materials.

Basal application to the cultivation layer: Before planting, spread powder-type (100 mesh) zeolite at about 200–1,000 kg per 10a (about 0.1 ha) over the soil surface layer 0–20 cm and till it in, increasing cation-retention sites from the start of the season. The sandier the soil, the closer to the upper end you consider.
Simultaneous blending with compost and organic fertilizer: Mixing zeolite in when spreading compost holds mineralized ammonium in place, so nutrients are not released all at once but supplied gradually throughout the season — a slow-release effect.
Slow-release nutrient carrier (NH₄⁺ pre-loading): Soaking zeolite beforehand in a dilute ammonium/liquid-manure solution to load NH₄⁺ into the channels, then applying it, lets it serve as a slow-release carrier that slows the nutrient release rate and reduces leaching. Note that unmodified zeolite cannot directly load anionic nutrients such as phosphate, so if phosphorus slow-release is the goal, a cationic-surfactant-modified zeolite (SMZ) form is required separately.
Localized placement in ridges and planting holes: A method of partially mixing zeolite only into planting holes or ridges to concentrate fertilization in the crop root zone, raising retention capacity around the roots while reducing the amount applied.
Small-area pilot: A method of first applying a small sample to one or two ridges to check changes in soil CEC and pH and the growth response, then expanding to the whole field.

Recommended particle size and product specifications

For organic soil improvement, Powder (100 mesh, <150μm), which mixes evenly with soil particles so the cation-exchange surface acts immediately, is most suitable for basal application to the cultivation layer and for compost blending. To retain it in the ridge surface layer for stepwise action and to reduce dust drift, Fine Granule (30×50 mesh, 0.3–0.6 mm) is advantageous, and the same particle size is recommended for potting-soil and pot blends. Refer to the table below to select the product group that fits your purpose.

Product group	Mesh	Particle size	Typical use
Powder	100 mesh or finer	<150μm	Pozzolan, feed, powder adsorption
Fine Granule	30×50 mesh	0.3–0.6mm	Water treatment, filtration, soil
Medium Granule	14×40 mesh	0.4–1.4mm	Filter media, litter, bedding
Coarse Granule	8×14 mesh	1.4–2.4mm	Swimming pools, de-icing, large-scale filtration
Extra Coarse	4×8 mesh	2.4–4.8mm	Packed beds, air scrubbers

→ View products by mesh size · Product selection guide by application

On-site review points for organic farming

When applying zeolite as a soil amendment in certified organic cultivation, checking the following items together lets you manage both effectiveness and safety.

Baseline soil analysis: Before application, measure the soil's current CEC and pH, and determine the application amount on the premise that the effect is greater the lower the retention capacity (the lower the CEC) of the sandy soil.
Application-amount design: Start in the range of 200–1,000 kg per 10a according to crop type and soil texture, set the first season conservatively, and then adjust based on soil-test results.
Identify nutrient-loss pathways: Understand the application rate of existing compost and organic fertilizer and the tendency of nitrogen loss (leaching and ammonia volatilization), and clarify the goal of which loss the zeolite is to reduce.
Irrigation and drainage management: Because the nutrient-retention effect works together with soil moisture, check irrigation frequency and drainage conditions so that retained nutrients are not released all at once through excessive irrigation.
Organic-certification compliance: For organic or pesticide-free certified cultivation, it is essential to confirm in advance whether it is a natural mineral with no synthetic treatment and whether it is an OMRI Listed (KMI-10365, NOP Allowed) material.
Persistence: Because zeolite does not decompose in soil and retains its ion-exchange sites, there is no need to reapply the full amount every season; the retention effect accumulates and persists across multiple seasons.

→ View TDS (Technical Data Sheet) · View MSDS (Safety Data Sheet)

Organic soil-improvement FAQ

Is it safe to use natural zeolite in certified organic cultivation without jeopardizing certification?

KMIZEOLITE clinoptilolite is a natural mineral that has only been crushed and screened, with no synthetic treatment or chemical modification. It is OMRI Listed (KMI-10365, NOP Allowed) and covered by the U.S. EPA pesticide tolerance exemption (40 CFR 180.1001). It can therefore be applied as a soil amendment in certified organic cultivation. However, because material-list registration requirements may differ among certification bodies, it is safest to present the OMRI listing documentation to your certification consultant for confirmation before application.

Does zeolite replace chemical fertilizers, or does it improve fertilizer efficiency?

Zeolite itself contains almost no N, P, or K, so it is not a fertilizer but a soil amendment that holds nutrients in place. The negatively charged sites of CEC 1.6–2.0 meq/g reversibly retain ammonium (NH₄⁺) and potassium (K⁺) mineralized from compost and organic fertilizers, reducing leaching and ammonia volatilization losses and supplying nutrients gradually as a slow-release effect. As a result, the same amount of organic nutrients is used more efficiently.

Besides ammonium (NH₄⁺), does it also capture nitrate (NO₃⁻) and phosphorus (P)?

No. The nutrient-retention action of natural clinoptilolite is cation exchange occurring on a negatively charged framework, so it is strong toward positively charged nutrients such as ammonium (NH₄⁺), potassium (K⁺), and calcium (Ca²⁺), but it cannot directly adsorb negatively charged nutrients such as nitrate (NO₃⁻) and phosphate (PO₄³⁻). For nitrate and phosphate, there is only an indirect effect in which leaching is somewhat slowed by improved soil water retention. Therefore, unmodified natural zeolite should be considered with a focus on holding nitrogen at the pre-nitrification stage through NH₄⁺ retention; to directly load and slow-release anionic nutrients (such as phosphorus), an SMZ form with the surface modified by a cationic surfactant is required separately.

How much, and at what particle size, should I apply per 10a (about 0.1 ha)?

It varies by soil texture and crop, but generally a basal application to the cultivation layer is considered in the range of 200–1,000 kg per 10a, with the upper end applying to sandy soils that have lower retention capacity. Powder (100 mesh, <150μm), which mixes evenly and acts immediately, is suitable for basal application and compost blending, while Fine Granule (30×50 mesh) is considered when surface retention and dust reduction are needed. The exact amount is best determined through soil testing and a small-area pilot.

Once applied, how long does the effect last?

Zeolite does not biodegrade in soil and retains its ion-exchange sites, so there is no need to reapply the full amount every season; the nutrient- and water-retention effects accumulate and persist across multiple seasons. As reported in studies such as He et al. (2002), it remains in the soil and acts to reduce ammonia volatilization, so it is used as a material that builds a long-term foundation for soil nutrient-retention capacity.

Inquiries and sample requests

If you are considering applying zeolite in the field of organic farming soil aid, please contact us through the channels below.

Notice

Whether application is appropriate may vary depending on site conditions, regulations, and test results. Before actual application, testing and review suited to the site conditions must always be carried out first. Zeolite is best understood not as a cure-all for this field, but as a material that supplements existing processes.

Zeolite for Organic Farming Soil Aid