Zeolites: Big Soil Enhancers in Little Packages

Zeolites are minerals that contain tremendous surface area within tiny pieces. The folds, features and channels of zeolites electrostatically adsorb – microscopically hold onto – ions and polar molecules such as water, fertilizer and metals that are needed for proper plant growth. With adsorption, zeolites store and retain water and nutrients when these are abundant in soil. When water or nutrients become less abundant (such as when these have been consumed from the grow media by plants), zeolites release these back into the grow media.

How do zeolites hold onto all these different types of things? Unlike most other minerals, zeolites have a negative ionic charge. This allows zeolites to adsorb the cations (positively charged ions) that constitute most all nutrients and micronutrients, including potassium, phosphorous, calcium, magnesium, zinc, copper and nitrogen in ammonium form. Adsorbing these cations allows them to remain in the grow media instead of leeching out when rain comes, or the media is irrigated or watered. Runoff and waste are reduced, and nutrient availability is both evened out and improved. Moisture is retained in similar fashion, with the zeolite able to adsorb water based on the polarity of its molecules.

Natural zeolites are commonly used as soil amendments. Zeolites help control evaporation of water from soil and provide long-term soil enhancement. Added to agricultural soils, zeolites have been used to reduce the toxic impact of highly saline water on crops and plants since zeolites are highly able to adsorb salt ions when these are present in soil in high concentrations. Zeolites adsorb many different ions and heavy metals, reducing levels of contamination in soil. Through being more aggressive in gathering and holding onto toxic metals and contaminants than plants can be, zeolites lead to lessened bio-availability of undesirable contaminants and toxins.

Zeolites also increase soil aeration. Soil aeration is critically important for plants as roots access nutrition through gas exchange and compaction leads to root rot and premature plant death.

Zeolites aren’t just soil amendments: learn about other uses for zeolites.