Thanks Redhawk. I was hoping you would comment and I am really glad you did. After reading your massage, I dived into our academic data base and searched for zeolite and agriculture. Frankly, especially about soil, when I search for an
answer; I end up having 15 new questions and one sort of answer. I came across two articles that helped me to understand more on the subject. I have more questions though.
If there is any soul in
permaculture that uses zeolite in their sites, please chime in and share your experiences. What I am going to summarize is not sourced from practice, but academic research.
Those two articles are: "Zeolite-amended
cattle manure effects on sunflower yield, seed quality, water use efficiency and nutrient leach" (Gholamhoseini et al, 2012) and "Zeolites and their potential uses in agriculture" (Ramesh ad Reddy, 2011). The first article is focused on a solution on a particular problem while the second one is more of a review (It has more than 6 page long reference). Things on my cheat sheet:
-There are more than 40 naturally occurring zeolites. Clinoptilolite is one of them. They have an open three dimensional structure, with a lot of voids (similar to
biochar?)
-There have been some initial research on zeolites in Japan, but both articles lack reference on the subject. The main goal was to discover their potential as both carriers of nutrients and medium to free nutrients.
-Si/Al ratio is important for classifying zeolites. Higher the Si/Al ratio, the matter becomes more hyrophonic and will be more thermally stable. Cation content will be less.
-There is a table given for zeolite chemical composition given in (2) article. For Turkish Clinoptilolite the numbers are roughly
SiO2 (75%) CaO (3%) K2O (3.5%) Al2O3 (11%) Na2O (varies 0.1-0.6%) Fe2O3 (1.4%) MgO(1%).
For Oregon clin.
SiO2 (60%) CaO (5%) K2O (0.15%) Al2O3 (12%) Na2O (0.11%) Fe2O3 (0.9%) MgO(0.1%).
-Zeolites are used for nitrogen retention in soils. Most for research are focused on sandy soils. They have high cationic interchange capacity and a great affinity for NH4 and K ions. Decreases nitrate leaching up to 11%.
-Increase of tomato yield but no positive effect on sweet corn is reported. Increase of sunflower yield, protein content and such.
-Has a potential to be used as carrier of slow release fertilizers, cides and as a trap for heavy metals.
-20-25% mixture by final weight with manure compost is ideal. (14-25% range has very positive results depending on irrigation)
-Experiments showed zeolite incorporated with poultry manure served as effective fertilizer and soil conditioner (Leggo 2000)
-Reduces the plant availability of heavy metals (Cd, Pb, Cr, Zn, Cu)
-None of the articles mention problems related to aluminum toxicity.
There are some videos on youtube about its detox properties. I don't buy their claims. I didn't come across any article on their claims in ac. literature.
So long story short, I think it has a potential to look into. Maybe an alternative to biochar? It is best to do some experiments as you have already described.